Article: 94553 of rec.radio.amateur.homebrew From: "Paul M0EME" References: <434d3f61_1@mk-nntp-2.news.uk.tiscali.com> <8RsiW2CJNVTDFwZE@clintsmc.demon.co.uk> Subject: Re: Wanted PL519 valves Date: Thu, 13 Oct 2005 20:02:40 -0000 Message-ID: <434ebd63$1_3@mk-nntp-2.news.uk.tiscali.com> Thanks Clint, I have just got hold of 2 PL519's but no bases. I live in Chesterfield but didn't think to try JPG. I shall have a drive around, I know a TV repair shop local to try. "Clint Sharp" wrote in message news:8RsiW2CJNVTDFwZE@clintsmc.demon.co.uk... > In message <434d3f61_1@mk-nntp-2.news.uk.tiscali.com>, Paul M0EME > writes >>I need 4 PL519 valves for a 400w HF amp, has anyone got any for sale?????? >>Also 4 valve bases.... >> > You might want to try JPG electronics in Chesterfield? They might be able > to help, alternatively drive around and watch out for the scruffiest > looking TV repair shops you can find and ask in there. > -- > Clint Sharp Article: 94554 of rec.radio.amateur.homebrew From: Wim Lewis Subject: Re: Pulsing LEDs for higher efficiency Date: Thu, 13 Oct 2005 20:23:36 +0000 (UTC) Message-ID: References: <2-idnQXJaNeGAdDeRVn-rg@comcast.com> In article <2-idnQXJaNeGAdDeRVn-rg@comcast.com>, Tom Coates wrote: >I want to build some emergency lighting equipment using LEDs and 12V. A >friend told me that it is possible to get more light per Watt by pulsing the >LED to instantaneous levels well above its average ratings. As I understand it, this is not true --- it was true in a way for older LEDs, but isn't true for modern LEDs. Pulsing a diode above its rated current could get it to emit some of its light at shorter wavelengths, which were closer to the middle of the visible spectrum and so seemed brighter. But if you're not taking advantage of that effect, then I don't think pulsing gets you anything. The instantaneous output of the LED is proportional to the instantaneous current, and the percieved brightness of the pulsed light source is the same as the average brightness, if it's pulsing fast enough ( > 10 Hz or so ). So it works out that the percieved brightness is the same as it would be if you'd driven the LEDs with a constant current. If resistive losses are significant, then pulsing will actually reduce the overall efficiency, since resistive losses are proportional to the average of I^2. On the other hand, if your battery is at a higher voltage than you want to drive the LEDs, then pulsing them might be more efficient than using a linear regulator --- that has more to do with the inefficiency of the linear regulator than anything to do with the LEDs, though :-) I did some googling to refresh my memory about pulsed LEDs and found a short article on the subject: http://www.caves.org.uk/led/foot4.pdf On the other hand, I also found some articles on pulsed LEDs saying the opposite --- that the percieved brightness of a pulsed source is closer to the peak brightness than to the average brightness. It might be worthwhile tracking down some actual experimental data, or doing an experiment yourself... -- Wim Lewis , Seattle, WA, USA. PGP keyID 27F772C1 Article: 94555 of rec.radio.amateur.homebrew Message-ID: <434F598A.C6C9F482@rickfrazier.com> From: Rick Frazier Subject: High Voltage Caps for Plate Supply ?? Date: Fri, 14 Oct 2005 07:08:21 GMT I have an Ameritron AL-1200 amplifier, and it came (used) with a capacitor problem. Upon inspection, 4 of the caps and 3 of the resistors in the Plate supply have been replaced, and some of the caps are in pretty sad shape (not to mention half of them are 220uf and the other half 270uf...). Upon a closer examination of the unit and schematics, I find the plate voltage is expected to be at 3600 volts (more or less), the manual has a warning about avoiding transformer taps that produce over 3700 volts, and the total of the capacitor bank rating is 3600 volts. (8 caps in series, 450volt rating. Each cap is 220 uf, so the entire pack is 3600 volts, 26.25 uf) I was in high tech engineering (computers and peripherals) for 20 years, and we never ran electrolytics at anywhere near their rated voltage. Permissible margins for low voltage DC circuits were 50% or more margin. Typical rule of thumb was 100% margin (a 10 volt cap running on nominal 5 volt line, etc.). Even in an industry where every penny of component cost was significant, submitting a design with electrolytics running with as little 25% margin typically got a less than stellar response during design reviews, to say the least. So, I was very surprised to find the capacitor bank in the AL-1200 running at or slightly above the rating of the capacitors. It just looks like a problem waiting to happen to me. Judging by the components replaced by a previous owner, I think that at least some of the capacitors failed in the past, possibly catastrophically... As I wish to prevent (or at least reduce the likelihood of) this happening in the future, I'm looking for capacitors that can replace the existing ones with higher voltage units. Unfortunately, there just aren't many manufacturers that have 500 volt electrolytics in their product line, and probably few stocking distributors that would have any in stock (or order them for a small order quantity). The part numbers I have found that will work for me (in order of preference) are listed here: Cornell Dubilier (CDE) 520C271T500AB2B 270uf 500 volts 500C311T500AB2B 31o uf 500 volts 520C341T500AJ2B 550C361T500AJ2B 500C381T500AJ2B 520C401T500AC2B DCMC321T500AB2B DCMC401T500AJ2B ALS30/40 series BHC Aerovox ALS334H331D3L500 ALS30A331DE500 All of these are "computer grade" with screw terminals, and range from inverter duty down (in order, from the best are 550C, 520C, 500C, DCMC). Do you know of any distributor that currently stocks these? Price would be good too... I need 10 of any one part number. I am in process on gathering supplies to make my own PCB to use 10 caps (instead of 8) so if I can get the 500 volt capacitors, the rated capacitor bank will be 5000 volts and 27 to 39 uf, which should provide a decent margin for a 3600 volt supply (and not blow up if my line voltage rises and I see 3900 volts, which happened to me at a former QTH). There's _just_ enough room for the larger PCB for the 10 caps (and resistors) in place of the existing board with 8 of each. I know where to get CDE DCMC271T450AA2B (450 volt, 270uf) which would give me a 4500 volt 27uf pack, but really would prefer to have the extra margin of the 500 volt capacitors. I can wait a bit for reasonable lead times, as the amplifier doesn't need to be in operation next week, but I don't want to still be looking 3 or 4 months from now. I'd appreciate any leads to suppliers of any of the above capacitors (or their equivalents). I can't say that price is no object, or I'd just buy a big QRO amp and sit back, but that's not the way I do things... I should expect these caps are going to be somewhere north of $20 each, even at Qty 10. Thanks --Rick AH7H Article: 94556 of rec.radio.amateur.homebrew From: Dave Bullock Subject: Homebrew repair of Standard C110 Help! Date: Fri, 14 Oct 2005 07:51:33 +0100 Message-ID: Has anyone got a copy of (or know where to download) a service handbook/schematic for the Standard C110 2m handie. Alternatively has anyone encountered a fault where it transmits & receives, 10MHz above the indicated frequency on the thumbwheels? I would imagine there's a down mixer and the synth is not running at signal frequency for this age of rig? Are there jumpers/links inside that someone might have messed up as it will still transmit (out of band) with this fault? Please help.....thanks in anticipation... Dave Article: 94557 of rec.radio.amateur.homebrew From: "Roger Conroy" Subject: Re: Pulsing LEDs for higher efficiency Date: Fri, 14 Oct 2005 09:06:17 +0200 Message-ID: References: <2-idnQXJaNeGAdDeRVn-rg@comcast.com> "Wim Lewis" wrote in message news:dimfo8$29t$1@underhill.hhhh.org... > In article <2-idnQXJaNeGAdDeRVn-rg@comcast.com>, > Tom Coates wrote: >>I want to build some emergency lighting equipment using LEDs and 12V. A >>friend told me that it is possible to get more light per Watt by pulsing >>the >>LED to instantaneous levels well above its average ratings. > > As I understand it, this is not true --- it was true in a way for older > LEDs, but isn't true for modern LEDs. Pulsing a diode above its rated > current could get it to emit some of its light at shorter wavelengths, > which > were closer to the middle of the visible spectrum and so seemed brighter. > > But if you're not taking advantage of that effect, then I don't > think pulsing gets you anything. The instantaneous output of the LED is > proportional to the instantaneous current, and the percieved brightness > of the pulsed light source is the same as the average brightness, if it's > pulsing fast enough ( > 10 Hz or so ). So it works out that the percieved > brightness is the same as it would be if you'd driven the LEDs with > a constant current. > > If resistive losses are significant, then pulsing will actually reduce the > overall efficiency, since resistive losses are proportional to the > average of I^2. > > On the other hand, if your battery is at a higher voltage than you want > to drive the LEDs, then pulsing them might be more efficient than using > a linear regulator --- that has more to do with the inefficiency of the > linear regulator than anything to do with the LEDs, though :-) > > > I did some googling to refresh my memory about pulsed LEDs and found > a short article on the subject: > http://www.caves.org.uk/led/foot4.pdf > > On the other hand, I also found some articles on pulsed LEDs saying > the opposite --- that the percieved brightness of a pulsed source > is closer to the peak brightness than to the average brightness. > It might be worthwhile tracking down some actual experimental data, > or doing an experiment yourself... > > -- > Wim Lewis , Seattle, WA, USA. PGP keyID 27F772C1 If the brightness of an LED is a 1:1 linear relationship with the power supplied, that suggests that perceived brightness of a pulsed LED would be neither at the arithmetic mean (average) nor at the peak but rather at rms (root mean square). Comments? Article: 94558 of rec.radio.amateur.homebrew From: "jim.gm4dhj" References: <1129223703.817784.78650@f14g2000cwb.googlegroups.com> Subject: Re: uk.radio.amateur et al, a FAQ Message-ID: <_6J3f.110$sm1.36@newsfe5-win.ntli.net> Date: Fri, 14 Oct 2005 07:28:58 GMT "Billy Bean built a machine to see what it could do. He made it out of sticks and stones, and nuts and bolts and glue. The motor sang chuggle-a-rang, chuggle-a-ruggle-a-rator, And all of a sudden a picture appeared on the funny old cartoonerator Billy Bean built a machine to see what it would do, It did the funniest things he'd seen, So he called it his fun machine, machine, Billy Bean and his fun machine. Article: 94559 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA:GONSET 201 Amp Huge Diagram+ mo parts Message-ID: Date: Fri, 14 Oct 2005 13:21:47 GMT Huge Gonset fold out schmetic diagram + other parts too; see at http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy 73 heytubeguy Article: 94560 of rec.radio.amateur.homebrew From: "Asimov" Subject: High Voltage Caps for Plate Supply ?? Message-ID: References: <434F598A.C6C9F482@rickfrazier.com> Date: Fri, 14 Oct 2005 16:11:02 GMT "Rick Frazier" bravely wrote to "All" (14 Oct 05 07:08:21) --- on the heady topic of "High Voltage Caps for Plate Supply ??" RF> From: Rick Frazier RF> Xref: core-easynews rec.radio.amateur.homebrew:88241 RF> I have an Ameritron AL-1200 amplifier, and it came (used) with a RF> capacitor problem. [,,,] RF> I was in high tech engineering (computers and peripherals) for 20 RF> years, and we never ran electrolytics at anywhere near their rated RF> voltage. Permissible margins for low voltage DC circuits were 50% or RF> more margin. Typical rule of thumb was 100% margin (a 10 volt cap RF> running on nominal 5 volt line, etc.). Even in an industry where every RF> penny of component cost was significant, submitting a design with RF> electrolytics running with as little 25% margin typically got a less RF> than stellar response during design reviews, to say the least. [,,,] RF> Thanks RF> --Rick AH7H Rick, it is okay to run electro's at about 80% of their voltage spec. Electro's are formed at up to 140% of their final spec and can thus tolerate turn on surges. It is the turn-on surge spec that one should worry about because that is when the electro is vulnerable. At turn on an electro re-forms a little bit which draws a larger current than usual. If that current doesn't fall off rapidly enough the electro can become damaged and leak permanently. In the old days electros used to be stamped with both surge and working voltage ratings. Isn't using an electro at 50% of spec rather conserative? I might understand being this prudent with semiconductors. An electro also has a leakage current spec at the rated working voltage. There isn't a direct linear relation between voltage and leakage. The relation is more like a reverse exponential and the leakage current drops off a lot more at a lower percent of rated voltage. A*s*i*m*o*v ... Paul's Law: You can't fall off the floor. Article: 94561 of rec.radio.amateur.homebrew From: "Asimov" Subject: Re: Pulsing LEDs for higher efficiency Message-ID: References: Date: Fri, 14 Oct 2005 16:11:05 GMT "Roger Conroy" bravely wrote to "All" (14 Oct 05 09:06:17) --- on the heady topic of "Re: Pulsing LEDs for higher efficiency" RC> From: "Roger Conroy" RC> Xref: core-easynews rec.radio.amateur.homebrew:88243 RC> If the brightness of an LED is a 1:1 linear relationship with the RC> power supplied, that suggests that perceived brightness of a pulsed RC> LED would be neither at the arithmetic mean (average) nor at the peak RC> but rather at rms (root mean square). Comments? I'm pretty certain it is not a simple rms function because the duration of the visual persistance effect must be taken into account. If the peak brightness duration is long enough it will be perceived as brighter than the average. Consider that the eye's retina cone signal fades off say to 80% in 10 milliseconds after exposure to light. As long as the light pulse repetition rate is high enough such that it results in a drop of optic nerve signal less than the minimum light change that can be perceived then the light will be seen as continuously bright. You can always run a subjective experiment on your workbench with an led and a 555 timer used as an astable. A*s*i*m*o*v ... Forcast for tonight: Dark. Article: 94562 of rec.radio.amateur.homebrew From: Allodoxaphobia Subject: Re: Pulsing LEDs for higher efficiency Date: 14 Oct 2005 17:09:21 GMT Message-ID: References: On Fri, 14 Oct 2005 16:11:05 GMT, Asimov wrote: > "Roger Conroy" bravely wrote to "All" (14 Oct 05 09:06:17) > --- on the heady topic of "Re: Pulsing LEDs for higher efficiency" > > RC> From: "Roger Conroy" > RC> Xref: core-easynews rec.radio.amateur.homebrew:88243 > > RC> If the brightness of an LED is a 1:1 linear relationship with the > RC> power supplied, that suggests that perceived brightness of a pulsed > RC> LED would be neither at the arithmetic mean (average) nor at the peak > RC> but rather at rms (root mean square). Comments? > > I'm pretty certain it is not a simple rms function because the > duration of the visual persistance effect must be taken into account. > If the peak brightness duration is long enough it will be perceived as > brighter than the average. Perhaps. But, will it _illuminate_ any better? The OP wasn't interested in _staring_ at a bank of leds. :-) Maybe better discussed in rec.bio-tronics HI!HI! Jonesy -- Marvin L Jones | jonz | W3DHJ | linux Pueblo, Colorado | @ | Jonesy | OS/2 __ 38.24N 104.55W | config.com | DM78rf | SK Article: 94563 of rec.radio.amateur.homebrew From: "Richard W. Solomon, W1KSZ" Subject: Re: Powerpole 180A Connectors Message-ID: References: <6mbng1199dj1p6ji91rf198rrnh99jrr00@4ax.com> <9hnpg15mc8el1keek6gfnbkvbu2in37bgs@4ax.com> Date: Fri, 14 Oct 2005 18:55:17 GMT Not really, they stop at 75 Amps. 73, Dick, W1KSZ On Fri, 14 Oct 2005 06:53:25 -0500, "gb" wrote: >"Richard W. Solomon, W1KSZ" wrote in message >news:9hnpg15mc8el1keek6gfnbkvbu2in37bgs@4ax.com... >> No, they are the SINGLEPOLE Connectors. >> >> http://www.andersonpower.com/products/pp/sp.html >> >> 73, Dick, W1KSZ >> > >Powerx sells the entire line - give them a call or send an e-mail to their >sales department. >Powerwerz web page >http://www.powerwerx.com > > Article: 94564 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: epoxy instead of solder? TRY ADHESIVE Date: Fri, 14 Oct 2005 13:48:07 -0500 Message-ID: References: <4345bdb6_16@Output.100ProofNews.com> About 10 years ago there was considerable attention to this is the press. We looked into it and didn't find anything which looked promising and neither did the industry. For non critical circuitry, I suspect there is possibilities My idea (which was chuckeled at) was " conductive Velcro" Make parts with the loops and boards with the hooks. Easy repair, eh? Zip off the old, stuff on the new... No heat, no time to cure... Imagine a demo of this compared to solder in the early days... Let's look at the options for electronics assembly. Well you have two choices: 1- Dip everything in molten lead. 2- stuff 'n go. Which do you pick...Hmmm difficult chioce, eh? Ther ewas also something called "particle interface". Many small sharp conductive points on the PCB, but how to anchor the parts. This was intended for test fixtures. 73, Steve, K9DCI Article: 94565 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Pulsing LEDs for higher efficiency Date: Fri, 14 Oct 2005 14:16:50 -0500 Message-ID: References: While I understand the Persistance comment, I don't think this is it. A couple of things. The eye has to convert the light energy to chemical reaction/change and this takes energy. The perception, therefore, would also be a factor of energy and a short pulse has less energy than a long pulse, so this would bring you back into the average vs, RMS discussion and favor the RMS idea. In other words, One would think power is what is being received, just like our ears, so the RMS idea seems to have merrit. However, I recall reading that the eye is a "somewhat" peak detecting device (my paraphrasing of part peak / part RMS) and that was the reason (or part of the reason) that the pulsed LEDs looked brighter. BTW, shining the LED onto a surface would have the same argument, so "_staring_ at a bank of leds" isn't a factor. 73, Steve, K,9.D;C'I "Allodoxaphobia" wrote in message news:slrndkvpi1.6k6.bit-bucket@shell.config.com... > On Fri, 14 Oct 2005 16:11:05 GMT, Asimov wrote: > > "Roger Conroy" bravely wrote to "All" (14 Oct 05 09:06:17) > > --- on the heady topic of "Re: Pulsing LEDs for higher efficiency" > > > > RC> From: "Roger Conroy" > > RC> Xref: core-easynews rec.radio.amateur.homebrew:88243 > > > > RC> If the brightness of an LED is a 1:1 linear relationship with the > > RC> power supplied, that suggests that perceived brightness of a pulsed > > RC> LED would be neither at the arithmetic mean (average) nor at the peak > > RC> but rather at rms (root mean square). Comments? > > > > I'm pretty certain it is not a simple rms function because the > > duration of the visual persistance effect must be taken into account. > > If the peak brightness duration is long enough it will be perceived as > > brighter than the average. > > Perhaps. But, will it _illuminate_ any better? > The OP wasn't interested in _staring_ at a bank of leds. :-) > > Maybe better discussed in rec.bio-tronics HI!HI! > > Jonesy > -- > Marvin L Jones | jonz | W3DHJ | linux > Pueblo, Colorado | @ | Jonesy | OS/2 __ > 38.24N 104.55W | config.com | DM78rf | SK Article: 94566 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: High Voltage Caps for Plate Supply ?? Date: Fri, 14 Oct 2005 14:36:58 -0500 Message-ID: References: <434F598A.C6C9F482@rickfrazier.com> "Asimov" wrote in message news:MSGID_1=3a167=2f133.0_434fc152@fidonet.org... "Rick Frazier" bravely wrote to "All" (14 Oct 05 07:08:21) --- on the heady topic of "High Voltage Caps for Plate Supply ??" RF> From: Rick Frazier RF> [snip] RF> e never ran electrolytics at anywhere near their rated RF> voltage. Permissible margins for low voltage DC circuits were 50% or RF> more margin. Typical rule of thumb was 100% margin (a 10 volt cap RF> running on nominal 5 volt line, etc.). Rick, it is okay to run electro's at about 80% of their voltage spec. Electro's are formed at up to 140% of their final spec and can thus tolerate turn on surges. ... Isn't using an electro at 50% of spec rather conserative? ... A*s*i*m*o*v In Motorola, our practice on lytics ( & resistors) was 50% of rated Voltage (power), but that was in the 12 v. area. I don't know where this came from, but they had extensive accelerated test capability and field data said our stuff is known to keep on ticking... I seem to recall that in tube days you were much closer and 80% seems reasonable. 73, Steve, K9DCI Article: 94567 of rec.radio.amateur.homebrew From: Ken Scharf Subject: Re: Receiver bandwidth .. dayton filter find! References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> Message-ID: Date: Fri, 14 Oct 2005 17:16:21 -0400 nospam@nouce.bellatlantic.net wrote: > For VHF 3.2 would likely work well enough except if there is a > sporatic E opening and people tend to pile up. Then it's really wide! > > For filters I use microprocessor crystals in the ladder configuration. > With the correct shunt C and 4-8 crystals you can make a very fine > crystal filter with bandwisths from 2-400hz to as wide as you may > want. The design process is documented elsewhere (see EMRFD > and the handbook as well as internet). I build for 6 and 2m and have > built very nice ladder filters this way. Also since microprocessor > crystals in the range of 4-20mhz are dirt cheap it's also a help. > Also the higher the frequency the less likely dual conversion is > required to avoid images and allows the selectivity to be closer > to the antenna (better overload performance). > > My latest 6m rig uses 12mhz crystals, 8 of them for a 2.3khz > bandwidth at 6db and 3.9khz at 60db with symetrical skirts. > > > Allison > KB!GMX I managed to buy over 400 pcs of 8.3886mhz crystals on ebay, for just pennies each. I am planning on trying to build ladder filters with them. These crystals are in the larger HC6/u size holders which are supposed to work better than the miniature size used in the micro- processor crystals. First step would be to build the DDS vfo for the radio since I can program the DDS to function as a sweep generator for aligning the filter. With the DDS sweeping the output frequency while providing a sawtooth ramp to drive the scope sweep in step with the frequency sweep I could see the actual bandwith plotted on the scope. Article: 94568 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Receiver bandwidth .. dayton filter find! Message-ID: <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> Date: Fri, 14 Oct 2005 22:14:13 GMT On Fri, 14 Oct 2005 17:16:21 -0400, Ken Scharf wrote: >nospam@nouce.bellatlantic.net wrote: >> For filters I use microprocessor crystals in the ladder configuration. >> With the correct shunt C and 4-8 crystals you can make a very fine >> Allison >> KB!GMX >I managed to buy over 400 pcs of 8.3886mhz crystals on ebay, for >just pennies each. I am planning on trying to build ladder filters >with them. These crystals are in the larger HC6/u size holders which >are supposed to work better than the miniature size used in the micro- >processor crystals. The HC6 parts work fine as do the HC18, 49 and so on. The real trick is doing the work to measure and check the crystals for use and then calculate the capacitors and termination impedence based on that. For a little work you get fine filters dirt cheap. >First step would be to build the DDS vfo for >the radio since I can program the DDS to function as a sweep generator >for aligning the filter. With the DDS sweeping the output frequency >while providing a sawtooth ramp to drive the scope sweep in step >with the frequency sweep I could see the actual bandwith plotted on >the scope. While I have a DDS to do that with I found that using the first "high" crystal in a VXO that gets calibrated worked as well with a lot less fuss. Then I can use the same osc to sweep the filter later to test it by adding a varicap doide. Allison Article: 94569 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Choice of iron powder toriod? References: Message-ID: Date: Fri, 14 Oct 2005 23:12:27 GMT Hello William, > Get a copy of Amidon's catalog which gives detailed suggestions for powdered > iron and ferrite materials, based on many years of experience. > www.amidoncorp.com > Absolutely. I literally wore one of those catalogs to the point where you could see through several pages. Then there are the ARRL Handbook and their Antenna Book. Both well worth every penny. Regards, Joerg http://www.analogconsultants.com Article: 94570 of rec.radio.amateur.homebrew From: Ken Scharf Subject: Re: Receiver bandwidth .. dayton filter find! References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> Message-ID: <4iX3f.24439$5l.10934@bignews1.bellsouth.net> Date: Fri, 14 Oct 2005 19:38:37 -0400 nospam@nouce.bellatlantic.net wrote: > On Fri, 14 Oct 2005 17:16:21 -0400, Ken Scharf > wrote: > > >>nospam@nouce.bellatlantic.net wrote: >> >>>For filters I use microprocessor crystals in the ladder configuration. >>>With the correct shunt C and 4-8 crystals you can make a very fine >>>Allison >>>KB!GMX >> >>I managed to buy over 400 pcs of 8.3886mhz crystals on ebay, for >>just pennies each. I am planning on trying to build ladder filters >>with them. These crystals are in the larger HC6/u size holders which >>are supposed to work better than the miniature size used in the micro- >>processor crystals. > > > The HC6 parts work fine as do the HC18, 49 and so on. The real trick > is doing the work to measure and check the crystals for use and then > calculate the capacitors and termination impedence based on that. > For a little work you get fine filters dirt cheap. > > >>First step would be to build the DDS vfo for >>the radio since I can program the DDS to function as a sweep generator >>for aligning the filter. With the DDS sweeping the output frequency >>while providing a sawtooth ramp to drive the scope sweep in step >>with the frequency sweep I could see the actual bandwith plotted on >>the scope. > > > While I have a DDS to do that with I found that using the first "high" > crystal in a VXO that gets calibrated worked as well with a lot less > fuss. Then I can use the same osc to sweep the filter later to test > it by adding a varicap doide. > That would work fine, but with the DDS, I can program the actual frequency range to be swept and probably be able to calibrate the scope face to read the actual frequency 'break' points on the filter. Using the vxo method will get you a working filter quickly no doubt, but I will still need the DDS vfo for the finished rig, so I just figured I'd do that first. How many 'rocks' did you use in an SSB filter? I've seen some designs on the web with 6 crystals, would the shape factor be any better with 8 or more? (with over 400 crystals in the junk box I can go crazy, but I'd still have to find the capacitors :-). Article: 94571 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> <4iX3f.24439$5l.10934@bignews1.bellsouth.net> Subject: Re: Receiver bandwidth .. dayton filter find! Message-ID: Date: Sat, 15 Oct 2005 00:24:39 GMT "Ken Scharf" wrote in message news:4iX3f.24439$5l.10934@bignews1.bellsouth.net... > nospam@nouce.bellatlantic.net wrote: >> On Fri, 14 Oct 2005 17:16:21 -0400, Ken Scharf >> wrote: >> >> >>>nospam@nouce.bellatlantic.net wrote: >>> >>>>For filters I use microprocessor crystals in the ladder configuration. >>>>With the correct shunt C and 4-8 crystals you can make a very fine >>>>Allison >>>>KB!GMX >>> >>>I managed to buy over 400 pcs of 8.3886mhz crystals on ebay, for >>>just pennies each. I am planning on trying to build ladder filters >>>with them. These crystals are in the larger HC6/u size holders which >>>are supposed to work better than the miniature size used in the micro- >>>processor crystals. >> >> >> The HC6 parts work fine as do the HC18, 49 and so on. The real trick >> is doing the work to measure and check the crystals for use and then >> calculate the capacitors and termination impedence based on that. >> For a little work you get fine filters dirt cheap. >> >> >>>First step would be to build the DDS vfo for >>>the radio since I can program the DDS to function as a sweep generator >>>for aligning the filter. With the DDS sweeping the output frequency >>>while providing a sawtooth ramp to drive the scope sweep in step >>>with the frequency sweep I could see the actual bandwith plotted on >>>the scope. >> >> Just sweeping a filter designed for SSB would be fine I suppose. I recently had an opportunity to hear the difference between a stock FT-1000 CW filter and one homebrewed with attention paid to group delay- the difference was very clear to hear- in favor of the homebrew filter. \ Dale Article: 94572 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Receiver bandwidth .. dayton filter find! Message-ID: References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> <4iX3f.24439$5l.10934@bignews1.bellsouth.net> Date: Sat, 15 Oct 2005 01:50:08 GMT On Fri, 14 Oct 2005 19:38:37 -0400, Ken Scharf wrote: >> >That would work fine, but with the DDS, I can program the actual >frequency range to be swept and probably be able to calibrate the >scope face to read the actual frequency 'break' points on the filter. >Using the vxo method will get you a working filter quickly no >doubt, but I will still need the DDS vfo for the finished rig, so >I just figured I'd do that first. Makes sense. I found the other way easy when DDS chips were 55$ each! The varicap sweep is calabrated to the scope so that was not an issue for sweeping the filter. I found that using wideband noise and a sound card was better. >How many 'rocks' did you use in an SSB filter? I've seen some designs >on the web with 6 crystals, would the shape factor be any better with >8 or more? (with over 400 crystals in the junk box I can go crazy, >but I'd still have to find the capacitors :-). I'd say 4 is a useable minimum. With that I'll add the skirts at 40db down are not very good though. I've used 6-8 to get a good 6-60db shape (under 2:1). There is a problem if you go for too many. The filter can have enough group delay that while it's shape is good, the sound has a hollowness. The caps, once you figured the qalues you will likely end up using parallel values. IE: 232pf may be a 220+12pf or a 220 and a 4-20pf trimmer. Allison Article: 94573 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Receiver bandwidth .. dayton filter find! Message-ID: References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> <4iX3f.24439$5l.10934@bignews1.bellsouth.net> Date: Sat, 15 Oct 2005 01:55:41 GMT On Sat, 15 Oct 2005 00:24:39 GMT, "Dale Parfitt" wrote: >Just sweeping a filter designed for SSB would be fine I suppose. I recently >had an opportunity to hear the difference between a stock FT-1000 CW filter >and one homebrewed with attention paid to group delay- the difference was >very clear to hear- in favor of the homebrew filter. >\ >Dale My prefered filter has a gausian to 6db shape for less ringing and group delay. I work for that goal. However, try the KK7B Phasing rigs for sound. They are direct conversion SSB (image rejecting) so all the selectivity is in the audio bandpass. I use a miniR2 and T2 pair on 6m and filter artifacts like group delay aren't there. Transparentcy is a good word to describe it. Allison KB1GMX Article: 94574 of rec.radio.amateur.homebrew Message-ID: <4350AE03.B6CE0065@rickfrazier.com> From: Rick Frazier Subject: Re: High Voltage Caps for Plate Supply ?? References: <434F598A.C6C9F482@rickfrazier.com> Date: Sat, 15 Oct 2005 07:21:02 GMT Asimov and Steve: I would agree, designs for lower voltage operations (at 50% of spec) tend to be much more conservative, particularly when the actual cost differential isn't that great, but it really does seem to cut down the failure rate. Also agree on the 80% figure, and that's what I'm trying to achieve (at minimum) with the change to higher voltage caps, (and relayout of the pcb to use 10 caps). Even if I can't get the higher voltage 500V caps, I can still get nearly 20% margin at the nominal 3600volt DC level, leaving some extra capacity for an occasional surge... I remember testing 50 caps at a time in my "blast box" to see how long they would withstand their surge rating. Yep, more than a few disintegrated during the testing, and many bulged without actually coming apart, all within as little as a few hours at the rated surge voltage. If I remember correctly, I also saw about a 5% failure rating at rated voltage within a few hundred hours, though the particular units tested at that time weren't computer grade or inverter grade caps like the part numbers I'm currently looking for. Of course, testing with a higher ripple content always broke the caps down faster than nearly pure DC, but you'd expect that just from the heating effect of the ripple current alone. Sometimes I don't even want to think about the hours that were dedicated to finding caps with both a low leakage figure that had a decent margin, and a long life so they could be used on part of a product that spent about a third of it's time on (lithium) battery power. Most caps are no longer marked for surge, but the datasheets typically show the surge rating. Unfortunately, you have to be very careful with surge figures, because some manufacturers seem to provide "absolute maximum" ratings instead of safe "momentary" surge ratings. Of course, it's up to the purchaser to determine whether the published ratings are satisfactory for the intended use (as I was quoted on many an occasion when inquiring of the manufacturer in years past. Just try to get a manufacturer to state in writing what they mean by "momentary"... Having performed "accelerated aging" tests to help determine the failure rate of stressed components, and compared it to actual field failures, I know that it isn't an exact science by any means. At least this is only a capacitor. Just try to get decent information on a battery (numerous experiments with lithium thionyl chloride types comes immediately to mind... ) is like searching for chickens with teeth. If capacitor manufacturers treat their products like some battery manufacturers did 10 years ago, it's a wonder they even stamp a rating on them... Of course, a tolerance rating of -10%, +50% on a capacitor should be a telling item to begin with... [sigh] Thanks for the response. --Rick Asimov wrote: > "Rick Frazier" bravely wrote to "All" (14 Oct 05 07:08:21) > --- on the heady topic of "High Voltage Caps for Plate Supply ??" > > RF> From: Rick Frazier > RF> Xref: core-easynews rec.radio.amateur.homebrew:88241 > > RF> I have an Ameritron AL-1200 amplifier, and it came (used) with a > RF> capacitor problem. > [,,,] > RF> I was in high tech engineering (computers and peripherals) for 20 > RF> years, and we never ran electrolytics at anywhere near their rated > RF> voltage. Permissible margins for low voltage DC circuits were 50% or > RF> more margin. Typical rule of thumb was 100% margin (a 10 volt cap > RF> running on nominal 5 volt line, etc.). Even in an industry where every > RF> penny of component cost was significant, submitting a design with > RF> electrolytics running with as little 25% margin typically got a less > RF> than stellar response during design reviews, to say the least. > [,,,] > RF> Thanks > RF> --Rick AH7H > > Rick, it is okay to run electro's at about 80% of their voltage spec. > Electro's are formed at up to 140% of their final spec and can thus > tolerate turn on surges. It is the turn-on surge spec that one should > worry about because that is when the electro is vulnerable. At turn on > an electro re-forms a little bit which draws a larger current than > usual. If that current doesn't fall off rapidly enough the electro can > become damaged and leak permanently. In the old days electros used to > be stamped with both surge and working voltage ratings. > > Isn't using an electro at 50% of spec rather conserative? I might > understand being this prudent with semiconductors. An electro also has > a leakage current spec at the rated working voltage. There isn't a > direct linear relation between voltage and leakage. The relation is > more like a reverse exponential and the leakage current drops off a > lot more at a lower percent of rated voltage. > > A*s*i*m*o*v > > ... Paul's Law: You can't fall off the floor. Article: 94575 of rec.radio.amateur.homebrew From: "tox" References: <1129378615.875533.71890@f14g2000cwb.googlegroups.com> Subject: Re: Prompted by Leigh Preece M5GWH - The weekly FAQ Message-ID: Date: Sat, 15 Oct 2005 13:09:54 GMT "Polymath" wrote in message news:1129378615.875533.71890@f14g2000cwb.googlegroups.com... Coming to Llandudno, Gareth? Will you be eavesdropping in, on my private conversations again? You really are a stupid boy! tox Article: 94576 of rec.radio.amateur.homebrew From: "William E. Sabin" References: Subject: Re: Choice of iron powder toriod? Message-ID: <3B74f.437160$x96.227112@attbi_s72> Date: Sat, 15 Oct 2005 13:35:59 GMT Hello Joerg, nice to meet you for the first time. Bill W0IYH "Joerg" wrote in message news:vXW3f.1513$D13.478@newssvr11.news.prodigy.com... > Hello William, > >> Get a copy of Amidon's catalog which gives detailed suggestions for >> powdered iron and ferrite materials, based on many years of experience. >> www.amidoncorp.com >> > > Absolutely. I literally wore one of those catalogs to the point where you > could see through several pages. > > Then there are the ARRL Handbook and their Antenna Book. Both well worth > every penny. > > Regards, Joerg > > http://www.analogconsultants.com Article: 94577 of rec.radio.amateur.homebrew From: "Denton" Subject: MFJ homebrew parts? Date: Sat, 15 Oct 2005 07:38:57 -0700 Message-ID: <11l25489e7d33f3@corp.supernews.com> I notice in the new 2006 MFJ catalog there is listed several roller inductors, turns counter and crank, among various sundry parts for homebrewing. Their prices seem to be most resonable....wonder how good their quality? I am looking to procure a roller inductor, turns counter plus crank for a homebrew ant tuner. Article: 94578 of rec.radio.amateur.homebrew From: "William E. Sabin" References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> <4iX3f.24439$5l.10934@bignews1.bellsouth.net> Subject: Re: Receiver bandwidth .. dayton filter find! Message-ID: <6J84f.437250$x96.418250@attbi_s72> Date: Sat, 15 Oct 2005 14:52:50 GMT A common mistake in years past was to try to put all of the selectivity into a single super-deluxe crystal, mechanical or digital filter. These filters quite often have "raspy" noise interference at the edges of the passband (especially in CW mode) due to the enhancements of spectral noise peaks at the very sharp band edges, caused by the conversion of the phase statistics of noise to amplitude statistics (each edge of the filter acts like a phase disciminator). This raspy noise interferes with weak signals. The filter can be equalized for group delay, as mentioned, with improvement in the problem. The band edges can be softened, with good results. A much better way is to use two or more intermediate-performance filters in cascade. This method softens the edges so that the effect is greatly reduced. It also improves overall shape factor. A cascade in this manner of identical bandpass or audio lowpass filters tends in the limit toward the Bessel or even the Gaussian response. Digital filters can also use a method called Transition Band Sampling (see Oppenheim and Schafer 1975 or Oppenheim and Willsky 1983). All of these results are related in principle to the Central Limit Theorem of statistics. The cascaded filter approach is also very beneficial in other respects, in particular the reduction of wideband noise in high-gain IF amplifiers. This noise degrades AGC performance and adds audio frequency noise to the product detector output. Bill W0IYH "Dale Parfitt" wrote in message news:b%X3f.301$W32.225@trnddc06... > Just sweeping a filter designed for SSB would be fine I suppose. I > recently had an opportunity to hear the difference between a stock FT-1000 > CW filter and one homebrewed with attention paid to group delay- the > difference was very clear to hear- in favor of the homebrew filter. > \ > Dale > Article: 94579 of rec.radio.amateur.homebrew From: Jim Adney Subject: Re: High Voltage Caps for Plate Supply ?? Date: Sat, 15 Oct 2005 10:50:49 -0500 Message-ID: References: <434F598A.C6C9F482@rickfrazier.com> On Fri, 14 Oct 2005 07:08:21 GMT Rick Frazier wrote: >I was in high tech engineering (computers and peripherals) for 20 years, >and we never ran electrolytics at anywhere near their rated voltage. >Permissible margins for low voltage DC circuits were 50% or more >margin. Typical rule of thumb was 100% margin (a 10 volt cap running on >nominal 5 volt line, etc.). Even in an industry where every penny of >component cost was significant, submitting a design with electrolytics >running with as little 25% margin typically got a less than stellar >response during design reviews, to say the least. Your margin would be determined by your tolerance for failure. If you're making 10,000 units per year, each with 10 caps in them and want to keep your cap related failures to less than, say, 10 per year, then you need to be a lot more conservative than if you have a single device with 10 caps in it that you want to keep your odds for failure under 1% per year. For most of the items I fix around here, I like to approach the problem in a way that I can think of the solution as permanent, but when you have a sample of just one, a 1% annual failure rate is about as close to perfect as you'll ever get, I'd say that for 450V caps, you're being much too conservative. We have banks of 450V caps at work, each bank with about 200 caps in it. They are used for energy storage and charged slowly and discharged rapidly about every 5 minutes all day long. We have about 10 such banks. We have occasional failures, maybe 1 cap every 3-4 years. We don't think that's too bad. I'm currently working on some upgrade banks which will have about 90 16,000 uF, 450V caps per bank. These will be run at 450V, and we'll have 16 such banks in the second phase of the project. United Chemi-Con doesn't seem to have any problem with this. We expect occasional failures, but we also realize that anything else is just being unrealistic. C-D lists computer grade caps rated at 500 and 550 V, each with surge ratings higher than that. United C-C does, too, but they admit that their etched alum foil for those voltages is not as advanced as at 450V, so the energy density is not as high. This does not sound like it would be a problem for you. Another thing we noted with interest was that the C-D catalog said that grading resistors were not necessary when installing caps in series for higher voltages, especially if all the caps were from the same batch. If I were you, I would just buy the caps you need/want at 450V, and then buy a couple of spares from the same batch. You would want to reform these if you ever needed them, but they would give you the necessary assurance that you'd be set for life. - ----------------------------------------------- Jim Adney jadney@vwtype3.org Madison, WI 53711 USA ----------------------------------------------- Article: 94580 of rec.radio.amateur.homebrew From: Subject: Complete Heathkit Station Message-ID: Date: Sat, 15 Oct 2005 17:46:02 GMT SB 630, SB 200, SB 101 autopatch/swr/powersupply/speaker, untested, estate sale, needs power cable Octal plug/jack and wire-missing. No mic, I am keeping. Email direct to N5TDE@gardcircuits.com leave message for Ross or Kassey I will send JPGS back. 73s, N5TDE Article: 94581 of rec.radio.amateur.homebrew From: Conrad Poos Subject: Re: Prompted by Leigh Preece M5GWH - The weekly FAQ References: <1129378615.875533.71890@f14g2000cwb.googlegroups.com> Message-ID: Date: Sat, 15 Oct 2005 20:43:32 GMT Mr. E wrote: > You really are a sociopathic imbecile, aren't you? Do grow > up and learn how to behave youself properly, you pathetic little man. Polymathazine (Eggy 2,4-Dimethyl Beanoxide) should be taken with extreme caution by patients with cardiovascular disease and high blood pressure. Polymathazine is a potent psychobabble agent and increased pulse rate and transient hypotension have both been reported in some patients exposed to this toxic and irritating substance. Use Polymathazine cautiously in patients with a history of seizures since the substance tends to lower the seizure threshold and frequently leads to the red mist. In general, Polymathazine does not produce psychic dependence; however, gastritis, extreme nausea and vomiting, dizziness, and tremulousness have been reported. CHECK WITH YOUR DOCTOR AS SOON AS POSSIBLE if you experience changes in vision; Tourettes fucking syndrome, changes in breasts and nips; changes in menstrual cycle or moped; deep throat; hysterical laughing, genital rash, muscle spasms of face, neck, or arse; difficulty swallowing his crap; spunk gurning and bubbling; mask-like face; tremors of hands; restlessness; tension in legs or weakness of arms or legs; sonic diarrhoea and frequent nightmares. Dr Poos -- vy 73 de Conrad Poos "Ich bin ein radio amateur" Article: 94582 of rec.radio.amateur.homebrew Message-ID: <4351B8D6.5BB4C82B@rickfrazier.com> From: Rick Frazier Subject: Re: High Voltage Caps for Plate Supply ?? References: <434F598A.C6C9F482@rickfrazier.com> Date: Sun, 16 Oct 2005 02:19:32 GMT Jim: Thanks for the response. Wow, with cap banks like you describe, there's some significant energy there... What are you working on, a pulsed cyclotron? Let's see, given your 10 banks with 200 caps each, that's 2000 caps and only 1 failure every three years, your failure rate is nearly insignificant. With a failure rate that low and a cycle rate you described, I'm supposing you are charging them with nearly pure DC, but without knowing the application, it's hard to guess... Of course, 200 caps in parallel mean leakage of about 800ma, so you've got to have a pretty good supply charging those caps. A bank of 90 caps at 16000uf each looks like 1.4 farads. That's an incredible amount of storage at first look. The leakage alone on a bank like that would be about 400ma. To charge them slowly, I'd be interested in knowing the charge time, and what is being used to limit the charge current. Is it an active supply with a ramped current, or as simple as really high wattage limiting resistors? In the linear amplifier, there are really a couple of things that tend to kill the caps. First, the ripple current tends to heat the caps, which are in a relatively warm location to begin with, sitting right next to a fairly large transformer, and a full wave bridge just above them. The transmitting tube is on the "other side of the wall" so to speak, but I'm sure it does contribute to some heat in the area. I haven't had this particular amplifier up and running yet, so can't instrument it to find out what the temperatures are, but I wouldn't be surprised to find it at 50C or higher, as the cooling air is all directed into the tube chimney and no particular attention has been made to cooling the capacitor bank. Given the ripple current, I wouldn't be surprised to see 80C, which is dangerously near the rated temperature rating (at least for me). Next, we have the typical cycle service an amateur amplifier puts these through, with a nearly uncontrolled charge (limited somewhat by a series resistor in the primary supply for the first second or so on an initial power up), and the demands as the amplifier is used. Now, given that the capacitor bank is never fully discharged, and the voltage across the bank is 3600 volts, the transformer rated at only 0.8 amperes, and the amount of current required during typical transmission, the heating from ripple current is probably the biggest concern for the initial design. However, given that I live in an area with less than perfect regulation of the incoming AC line, I tend to be a bit gun-shy about what I see personally as a "marginal" design. At my last QTH, the line voltage per our local Hawaiian Electric Light Company (HELCO) should have been between 230 and 240 volts. I was the last house on the end of a 1 mile run of utility poles, and the transformer, which was over 300 feet from the building, served only my house and workshop at the time. In my workshop, I ran a single phase to 3 phase solid state inverter for a 3 horsepower wood lathe. During a period of two years, even with rather sporadic use after the first year, I had four inverters fail, and the failure was always the input diode bridge. After the first failure, I instrumented the AC line and kept graphs on it. The line voltage ranged from 235 to 243 volts over the typical 24 hour period, and tended to be around 239 volts much of the time, which I see as the nominal voltage for that location. Unfortunately, there were times when the voltage would rise to as much as 255 volts for brief periods of time (usually only a few seconds, but one prolonged instance went over 15 seconds). I didn't actually catch any high line spikes during operation of my lathe, but there were times I forgot to turn off the inverter and would come back and find it dead in the water a couple of days later. I finally eliminated the problem by putting a buck/boost transformer in the circuit, reducing the nominal voltage to 227 volts. Now there is a definite possibility the particular inverter input bridge wasn't properly rated, or wasn't up to spec, but all problems went away once I got the line voltage down (and the observed spikes at or below 243 volts). Now thinking about the amplifier, which is supposed to produce 3600 volts with a nominal 240 volt input. Given some likelihood of seeing spikes to 255 volts, I could easily imagine the capacitor bank seeing 3825 volts for as much as 15 seconds. OK, not a long time, considering the really big picture, but looking inside the amplifier and seeing that three of the bridging resistors (50K ohm, 7 watts) and 4 of the capacitors were replaced at some time in its history, I am tending towards getting more margin into the design. My tolerance for failure is low. I would prefer to get this amplifier up to snuff, put it into service, and never have to open the case again. I know that's a fairly high goal, but the AL-1200 uses one of the longest lived tubes in this type of service, and I'm unlikely to overdrive it so long as I load it properly, as it can withstand 130 watts and both of my transceivers only put out 100 watts.. I can purchase the 450 volt capacitors for about $10 each, so the 10pc bank will cost me about a hundred dollars. Add another $25 for new resistors and $20 for the supplies to layout the PCB for 10 caps, I'm looking at $145 to have a 4500 volt capacitor bank. If I can get the 500 volt capacitors, they will likely cost $25 to $30 each (lower volume, fewer dealers, etc.) and I would have a 5000Volt capacitor bank for $295 to $345 out of pocket. If I just replaced the caps and resistors on the original PCB, I'd be out $125, but have a 3600 volt bank. With 500 volt capacitors I'd be at 4000 volts. Given the circumstances of apparent previous failure(s) and my low tolerance for failure 'on my watch', I would feel better having the extra headroom, even with a price premium well over double. (Funny how it comes around to the warm fuzzy feelings isn't it?) Of course, f I don't find a supplier for the 500 volt capacitors fairly soon, impatience will take over and I'll end up buying the 450 volt ones anyway! Of course, in the back of my mind (and not previously mentioned) is the possibility of running the amplifier from the 220 volt tap on the transformer, which would give me 3925 volts nominal on the bank at 240 volts, and 4010 volts on the bank at 245 volts, and 4175 if I see the same sort of 255 volt spike at the new QTH. I've done dumber things in my life and could see a possibility of it happening in a moment of weakness, so I'm also buying some insurance by going to the higher voltage capacitors and the new PCB. The biggest reason to run a higher voltage would be to allow getting full legal output with a lower drive from the transceiver. I would prefer to run with less than 100 watts out from the transceiver, but thinking about it, it would likely only be about 10% or so less drive, so perhaps it isn't worth all the work for that reason alone. Thanks --Rick Jim Adney wrote: > On Fri, 14 Oct 2005 07:08:21 GMT Rick Frazier > wrote: > > >I was in high tech engineering (computers and peripherals) for 20 years, > >and we never ran electrolytics at anywhere near their rated voltage. > >Permissible margins for low voltage DC circuits were 50% or more > >margin. Typical rule of thumb was 100% margin (a 10 volt cap running on > >nominal 5 volt line, etc.). Even in an industry where every penny of > >component cost was significant, submitting a design with electrolytics > >running with as little 25% margin typically got a less than stellar > >response during design reviews, to say the least. > > Your margin would be determined by your tolerance for failure. If > you're making 10,000 units per year, each with 10 caps in them and > want to keep your cap related failures to less than, say, 10 per year, > then you need to be a lot more conservative than if you have a single > device with 10 caps in it that you want to keep your odds for failure > under 1% per year. > > For most of the items I fix around here, I like to approach the > problem in a way that I can think of the solution as permanent, but > when you have a sample of just one, a 1% annual failure rate is about > as close to perfect as you'll ever get, > > I'd say that for 450V caps, you're being much too conservative. We > have banks of 450V caps at work, each bank with about 200 caps in it. > They are used for energy storage and charged slowly and discharged > rapidly about every 5 minutes all day long. We have about 10 such > banks. We have occasional failures, maybe 1 cap every 3-4 years. We > don't think that's too bad. > > I'm currently working on some upgrade banks which will have about 90 > 16,000 uF, 450V caps per bank. These will be run at 450V, and we'll > have 16 such banks in the second phase of the project. United > Chemi-Con doesn't seem to have any problem with this. We expect > occasional failures, but we also realize that anything else is just > being unrealistic. > > C-D lists computer grade caps rated at 500 and 550 V, each with surge > ratings higher than that. United C-C does, too, but they admit that > their etched alum foil for those voltages is not as advanced as at > 450V, so the energy density is not as high. This does not sound like > it would be a problem for you. > > Another thing we noted with interest was that the C-D catalog said > that grading resistors were not necessary when installing caps in > series for higher voltages, especially if all the caps were from the > same batch. > > If I were you, I would just buy the caps you need/want at 450V, and > then buy a couple of spares from the same batch. You would want to > reform these if you ever needed them, but they would give you the > necessary assurance that you'd be set for life. > > - > ----------------------------------------------- > Jim Adney jadney@vwtype3.org > Madison, WI 53711 USA > ----------------------------------------------- Article: 94583 of rec.radio.amateur.homebrew Subject: ** FLEA at MIT ** Sunday October 16th Cambridge MA From: w1gsl@mit.edu (Steven L. Finberg) Date: 16 Oct 2005 05:00:41 GMT Message-ID: <4351de79$0$556$b45e6eb0@senator-bedfellow.mit.edu> This Sunday.... The seasons last... +++ Now even more Buyers Parking !!! Thanks to TKT we have use of their new parking lot across Albany St from the SWAPFEST !!! !! ** More Buyers PARKING is available ** for details see http://web.mit.edu/w1gsl/Public/flyer *** !!!! In our Traditional GARAGE and the adjacent lot !!!! **** so come rain or shine or super heat the Flea is on !!! ********* $1 buyers discount with hardcopy of this notice ******** COMPUTERS - ELECTRONICS - HAM RADIO - COMPUTERS - ELECTRONICS - HAM RADIO FLEA all SUMMER at MIT Sunday October 16th 2005 9AM-2PM Come to the city for a great flea - plenty of free parking. MIT's electronics and ham radio flea will take place on the third Sunday of each month this summer, April thru October. There is tailgate space for over 600 sellers and free, off-street parking for >2000 cars! Buyers admission is $5 (you get $1 off if you're lucky enough to have a copy of our ad) and sellers spaces are $20 for the first and $15 for each additional at the gate. The flea will be held at the corner of Albany and Main streets in Cambridge; right in the Kendall Square area from 9AM to 2PM, with sellers set-up time starting at 7AM. SEASON PASS + Advance Seller Discount A sellers discount season pass is available which offers a 30% discount. By prepaying you get a discount and earlier admission. See the registration form. *** Attention Sellers *** Prepaid vendors.. Season Pass or monthly, will be admitted FIRST. Separate lines will form prior to gate opening for prepaid and nonprepaid vendors !! RAIN or SHINE !! Have no fear of rain, a covered well illuminated tailgate area is available for all sellers (6'8" clearance). Talk-in: 145.23- (PL 88.5) W1BOS/R and W1XM/R-449.725/444.725 (PL 114.8/2A). Sponsors: MIT Electronics Research Society MIT UHF Repeater Association (W1XM) MIT Radio Society (W1MX) Harvard Wireless Club (W1AF) For more info / advanced reservations 617 253 3776 ********** $1 buyers discount with hard copy of this notice ************ <<<<<<<<<<<<<<<<<<<<<<<< cut here >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Mail the coupon below by the 5th of the month to be a Prepaid Vendor. FLEA at MIT 2005 Rates SELLERS To use your prepaid spaces the named vendor MUST be present. Rates include one admission per space. Advance $17 First space - includes $10 Cambridge Vendor License $12 Additional Spaces Must be received by the 5th of the month. Gate Admission $20 First Space - includes $10 Cambridge Vendor License $15 Additional Spaces Admission is after the prepaid vendors Early Bird Buyer -Admission after the prepaid vendor line is admitted. ~ 7:15AM ** You may not sell. ** $15 per person at the gate. ****************************** cut here ******************************* FLEA at MIT 2005 Advance Space Application ____April ____May ____June ____ July ____Aug ___Sept ____Oct @ $17 for the first each month + $12 each additional Name ________________________ Call __________ $ Included______ Address ________________________ Phone __________ Make Check to The MIT Radio Society City ____________________ State _______ Zip _______ PO Box 397082 Cambridge MA 02139 E-mail _____________________________________________ ******************************************************************************* Steve Finberg W1GSL w1gsl@mit.edu PO Box 82 MIT Br Cambridge MA 02139-7082 617 258 3754 ******************************************************************************* Article: 94584 of rec.radio.amateur.homebrew From: Ian Jackson Subject: Re: OT: CQ Serenade Date: Sun, 16 Oct 2005 08:39:35 +0100 Message-ID: References: In message , Fred McKenzie writes >In article , "Johnson" > wrote: > >> a link posted on the French usenet group fr.rec.radio.amateur "CQ Serenade" >> http://www.von-info.ch/hb9afo/histoire/NON-CQ_cq_serenade_fr.mp3 > >You may also enjoy >http://www.von-info.ch/hb9afo/histoire/cw-rythm.mp3 > >73, Fred, K4DII Interesting! Could be useful for anyone learning morse. But the letters do sound a bit ragged. I hope nobody copies them exactly. Ian. -- Article: 94585 of rec.radio.amateur.homebrew From: "William E. Sabin" References: <18f19hicdgfnd$.7gnt1gih8f2b$.dlg@40tude.net> <13nlk1pum427n8anfbgm1eualjkfvpcque@4ax.com> <3g9nk15317t4fkiobq0h8i36vvg9s6arre@4ax.com> <17b0l1loe0r4184uar1jkd6pits85gkdfe@4ax.com> <4iX3f.24439$5l.10934@bignews1.bellsouth.net> <6J84f.437250$x96.418250@attbi_s72> Subject: Re: Receiver bandwidth .. dayton filter find! Message-ID: Date: Sun, 16 Oct 2005 12:19:37 GMT "William E. Sabin" wrote in message news:6J84f.437250$x96.418250@attbi_s72... A couple of improvements in the following paragraph: > The filter can be equalized for group delay, as mentioned, with > improvement in the problem. The band edges can be softened, with good > results. A much better way is to use two or more intermediate-performance > filters in cascade. This method softens the edges so that the effect is > greatly reduced. It also improves overall shape factor. A cascade in > this manner of identical bandpass or audio lowpass filters tends in the > limit toward the Bessel or even the Gaussian response. Digital filters > can also use a method called Transition Band Sampling (see Oppenheim and > Schafer 1975) Delete the incorrect second Reference to Oppenheim and Willsky 1983. > All of these results are related in principle to the Central Limit > Theorem of statistics. See http://mathworld.wolfram.com/CentralLimitTheorem.html for this interesting topic. The general idea that the theorem alludes to in this example is that as sharp-cornered filters are cascaded the passband response becomes noticeably more rounded at the corners, similar to Bessel and Gaussian filters. Smoothing and Windowing methods can be used to reduce sharp corners in discrete sequences such as digital filters (see Oppenheim and Schafer 1975 and many other sources). Bill W0IYH Article: 94586 of rec.radio.amateur.homebrew From: "Walter Raleigh" References: <1129484937.573780.64550@g44g2000cwa.googlegroups.com> Subject: Re: I seem to have forgotten the weakly FAQ, don't panic, here it is! Message-ID: <1qw4f.17239$R5.1675@news.indigo.ie> Date: Sun, 16 Oct 2005 18:50:52 +0100 "Polymath" wrote in message news:1129484937.573780.64550@g44g2000cwa.googlegroups.com... > What is Ham Radio? Oh thank you Gareth, we were all getting so worried... -- 73s de Walter R. Article: 94587 of rec.radio.amateur.homebrew From: "G1LVN \(for it is he\)" Subject: Re: I seem to have forgotten the weekly FAQ, don't panic, here it is! Date: Sun, 16 Oct 2005 19:06:13 +0000 (UTC) Message-ID: References: <1129484937.573780.64550@g44g2000cwa.googlegroups.com> "Mr. E" wrote in message news:diu6oi$ssc$0@pita.alt.net... > So far in the last 7 days you have posted this three times. > 13 October 2005 18:15:03 > 15 October 2005 13:16:55 > 16 October 2005 18:48:57 > You appear to have short term memory loss. > > Also, please answer my earlier question - exactly who is asking this > supposedly frequently asked question that makes you post your diatribe? > The voices in your head do NOT count, and I have not seen anybody else ask > what ham radio is. > > You really are a pathetic little man. > Coast is clear he'll have falling into a stupor by now. -- 73deG1LVN Join t eh Campaign now for MB7IHW!! http://www.g1lvn.org.uk/unattended/ Article: 94588 of rec.radio.amateur.homebrew From: "Jeff" References: Subject: Re: Choice of iron powder toriod? Message-ID: Date: Mon, 17 Oct 2005 08:51:59 +1300 Hi Guys, Results of the build and test were that the 7Mhz HPF worked very well with the "6" grade cores, but the 20Mhz LPF was crap (it used #6 as well). It started to roll off at 20Mhz as expected, dropped smoothly to -10dB by the time it got to 40Mhz, then stayed at 10dB at all frequencies above 40Mhz. I suppose the core should be a grade #10 or #12 instead of #6? or perhaps just a normal air core? JEFF "Jeff" wrote in message news:mQe3f.76$S24.9081@news.xtra.co.nz... > Thanks for all the suggestions. Ive got some Amidon T68-6 toroids to wind > up, and will test the completed filter on a spectrum analyser next week. > JEFF > > "Jeff" wrote in message > news:drW2f.17270$iM2.1412876@news.xtra.co.nz... > > Hi, > > Im confused regarding the choice of iron powder toroid for a 7Mhz high > pass > > filter. I need to use a small size (T68) toroid. For the freq range, some > > reference texts say T68-2 is the one, others say T68-6" grade. I see > > differing "best Q range" specs for the 6 > > grade.....2-30Mhz......10-50Mhz...etc. > > Have similar need for 20Mhz LPF, but assume "6" is really the choice > there. > > Any suggestions as to the relative differences and reasons to choose > between > > grades 2 and 6 for the HPF in T68 size? > > Thanks, > > JEFF > > > > > > Article: 94589 of rec.radio.amateur.homebrew From: "Harold E. Johnson" References: Subject: Re: Choice of iron powder toriod? Message-ID: Date: Sun, 16 Oct 2005 21:11:37 GMT "Jeff" wrote in message news:Cby4f.795$S24.49570@news.xtra.co.nz... > Hi Guys, > Results of the build and test were that the 7Mhz HPF worked very well with > the "6" grade cores, but the 20Mhz LPF was crap (it used #6 as well). It > started to roll off at 20Mhz as expected, dropped smoothly to -10dB by the > time it got to 40Mhz, then stayed at 10dB at all frequencies above 40Mhz. > I suppose the core should be a grade #10 or #12 instead of #6? or perhaps > just a normal air core? > JEFF Then you haven't built the filter that you designed. The choice of core material will not affect the blow-by. If you measured the inductors at a low frequency, I would be pretty certain that you have way too much inductance at 20-40 MHz. W4ZCB Article: 94590 of rec.radio.amateur.homebrew From: Jim Adney Subject: Re: High Voltage Caps for Plate Supply ?? Date: Sun, 16 Oct 2005 16:34:51 -0500 Message-ID: References: <434F598A.C6C9F482@rickfrazier.com> <4351B8D6.5BB4C82B@rickfrazier.com> On Sun, 16 Oct 2005 02:19:32 GMT Rick Frazier wrote: >Wow, with cap banks like you describe, there's some significant energy >there... What are you working on, a pulsed cyclotron? Plasma physics research facility. 2-4 minute charge cycle, 70 mSec discharge. These banks supply the crowbar, or "follow-on," current once the big 5 kV banks have discharged down. Yes the charging supplies are large, and the future ones will have to be even larger. We tend to go for some kind of constant current scheme, up to the preset voltage limit. I don't think our leakage current is nearly as high as you suggest. The caps tend to form nicely after awhile and the leakage current ramps down with use. Until one fails, of course. ;-) >A bank of 90 caps at 16000uf each looks like 1.4 farads. That's an >incredible amount of storage at first look. The leakage alone on a bank like >that would be about 400ma. I rounded. We're actually shooting for individual banks of .3F at 900V, so that takes 1.2F of 450V caps, times 16 of these banks. Charge/discharge is as above, leakage should be less that what you suggest, but I could be wrong about that. >In the linear amplifier, there are really a couple of things that tend to >kill the caps. First, the ripple current tends to heat the caps, which are >in a relatively warm location to begin with, sitting right next to a fairly >large transformer, and a full wave bridge just above them. I don't know how much internal heating you'll get, but temp is certainly something to be concerned with. Our application stays pretty much at room temp. >However, given that I live in an area with less than perfect regulation of >the incoming AC line, I tend to be a bit gun-shy about what I see personally >as a "marginal" design. At my last QTH, the line voltage per our local >Hawaiian Electric Light Company (HELCO) should have been between 230 and 240 >volts. I was the last house on the end of a 1 mile run of utility poles, and >the transformer, which was over 300 feet from the building, served only my >house and workshop at the time. In my workshop, I ran a single phase to 3 >phase solid state inverter for a 3 horsepower wood lathe. During a period of >two years, even with rather sporadic use after the first year, I had four >inverters fail, and the failure was always the input diode bridge. Did you consider upgrading the input bridge? I agree that excessive line voltage is a problem, but the bridge was clearly your weak link. >After the >first failure, I instrumented the AC line and kept graphs on it. The line >voltage ranged from 235 to 243 volts over the typical 24 hour period, and >tended to be around 239 volts much of the time, which I see as the nominal >voltage for that location. Unfortunately, there were times when the voltage >would rise to as much as 255 volts for brief periods of time (usually only a >few seconds, but one prolonged instance went over 15 seconds). I think the surge ratings for Al caps are for a 30 second surge. >OK, not a long time, considering the really big picture, >but looking inside the amplifier and seeing that three of the bridging >resistors (50K ohm, 7 watts) and 4 of the capacitors were replaced at some >time in its history, I am tending towards getting more margin into the >design. I agree that there's often room for improvement in amateur gear. Upping the resistor power ratings might be useful, too. If they run in the same ambient, then they should also be derated. >My tolerance for failure is low. I would prefer to get this amplifier up to >snuff, put it into service, and never have to open the case again. I agree with your goal, and I don't think running 450V caps at 450V will come back to haunt you. Just make sure that the 30 second surge rating is above the highest voltage you think you'll ever see. >Of course, in the back of my mind (and not previously mentioned) is the >possibility of running the amplifier from the 220 volt tap on the >transformer, which would give me 3925 volts nominal on the bank at 240 volts, >and 4010 volts on the bank at 245 volts, and 4175 if I see the same sort of >255 volt spike at the new QTH. With 10 caps, that's still less than 420 V/cap. I don't think that's any problem at all. - ----------------------------------------------- Jim Adney jadney@vwtype3.org Madison, WI 53711 USA ----------------------------------------------- Article: 94591 of rec.radio.amateur.homebrew Date: Sun, 16 Oct 2005 21:00:23 -0400 From: Bill Subject: Re: 40/50 Mix toroid specs? References: Message-ID: <8e0a6$4352f7ab$4232bd7b$17075@COQUI.NET> TRABEM wrote: > Any idea what this mix is good for? > > Thanks, Nope. Wind and test a few examples and you can probably get into a ballpark. If they are power supply toroids vs rf toroids, or ferrite vs powdered iron, that will quickly become obvious. The way the surplus market goes, most "found" toroids are power supply types and only good for that application. -Bill Article: 94592 of rec.radio.amateur.homebrew From: novatech@eskimo.com (Steven Swift) Subject: Re: Pulsing LEDs for higher efficiency Date: 17 Oct 2005 01:23:54 GMT Message-ID: References: <2-idnQXJaNeGAdDeRVn-rg@comcast.com> Wim Lewis writes: >On the other hand, I also found some articles on pulsed LEDs saying >the opposite --- that the percieved brightness of a pulsed source >is closer to the peak brightness than to the average brightness. >It might be worthwhile tracking down some actual experimental data, >or doing an experiment yourself... >-- > Wim Lewis , Seattle, WA, USA. PGP keyID 27F772C1 HP used to have a nice app note on this. The main trick is that the eye responds most nearly to intensity, which is close to being proportional to the square of the brightness (analogous to power vs voltage). Just like "pulsey" currents have higher RMS values, "pulsey" light can have a higher intensity. The eye acts as a smoothing filter. This is a well known trick in lots of lighting and display areas. If you really care, you can use LEDs as "catch" diodes in switching regulator circuits to get some pretty amazing "lumens per watt." Steve. -- Steven D. Swift, novatech@eskimo.com, http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA Article: 94593 of rec.radio.amateur.homebrew From: Me Subject: Free: Radiotron Designer's Handbook, 4th Edition Message-ID: <1129534498.bb01b1e635972b5cd17b9a3805016cb8@teranews> Date: Mon, 17 Oct 2005 00:34:38 -0700 http://thepiratebay.org/details.php?id=3397758 Article: 94594 of rec.radio.amateur.homebrew From: John Livingston Subject: Spectrum analyser adaptor Date: Mon, 17 Oct 2005 14:34:58 +0000 (UTC) Message-ID: Can anyone point me at a source for a servicing and calibration manual for a TTI TSA250 spectrum analyser adaptor ? Emails to TTi get no reply ... I've got the user manual, but that's no help. Failing a manual - info on which preset does what would be useful. John L York, UK Article: 94595 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: MFJ homebrew parts? Date: Mon, 17 Oct 2005 13:14:58 -0500 Message-ID: References: <11l25489e7d33f3@corp.supernews.com> MFJ has a dubious quality reputation from comments around these parts. They make Ham quality stuff and you must expect that. I'm not saying it's bad, just not gold plated and super high quality. Remember quality = $$. (thought he converse isn't always true) My roller inductor developed an intermittent after a few years and I had to solder one of the contacts - hard to get to, but the thing works ok as far as I can tell. I have an older one, I think 986, two knob "T". It has matched my 40M dipole on 75! 73, Steve, K9DCI "Denton" wrote in message news:11l25489e7d33f3@corp.supernews.com... > I notice in the new 2006 MFJ catalog there is listed several roller > inductors, turns counter and crank, among various sundry parts for > homebrewing. Their prices seem to be most resonable....wonder how good their > quality? > I am looking to procure a roller inductor, turns counter plus crank for a > homebrew ant tuner. > > Article: 94596 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: Pulsing LEDs for higher efficiency Date: Mon, 17 Oct 2005 13:23:49 -0500 Message-ID: References: <2-idnQXJaNeGAdDeRVn-rg@comcast.com> "Tom Coates" wrote in message news:YMmdnU7sTKSmMczeRVn-2Q@comcast.com... > Thanks, everyone, for the insights. I think I'll get it working without the > pulsing and then reconsider. > > It appears that what was described to me as a standard technique is much > more experimental. > > Tom, N3IJ > > "Tom Coates" wrote in message > news:2-idnQXJaNeGAdDeRVn-rg@comcast.com... > > I want to build some emergency lighting equipment using LEDs and 12V. A > > friend told me that it is possible to get more light per Watt by pulsing > the LED to instantaneous levels well above its average ratings. > > > > Is this true, if you include power consumed in the pulsing circuit? > > Tom, N3IJ Good luck...However. I did find one Agilent ap note about LEDs , but it didn't mention pulsed vs. non-pulsed brightness...much. I did build a pulsed LED driver a long time ago. It used an inductor and comparator. Turn on switch in series with LED, inductor ( tried 1mH first ) and supply. When current ramps up to the desired, turn off switch. A "catch" or "fly-wheel" diode then conducts current through LED & inductor while current decays to a lower level where switch turns on. Neat to see the supply current less than the LED current. 73, Steve, K9DCI Article: 94597 of rec.radio.amateur.homebrew From: "Steve Nosko" Subject: Re: epoxy instead of solder? Date: Mon, 17 Oct 2005 13:27:33 -0500 Message-ID: References: "John Fields" wrote in message news:haf8k1hs7u06ru7lgp10dpa81s1mdm37t3@4ax.com... > On Wed, 05 Oct 2005 16:10:40 -0400, TRABEM <> wrote: > > >Has anyone tried Masterbonds conductive epoxy for attaching SMT > >components to a printed circuit board? > > > >Seems like a great idea, especially if it works well:>: > > --- > Aside from the resistivity of the epoxy, the largest problem I see > is throughput. That is, where are you going to store all those > boards while the epoxy is curing? > Plus, it makes it really messy for the salvagers/recyclers. > -- John Fields Professional Circuit Designer In a production line they would probably use UV curing epoxies. They already do, but not for solder substitute. 73, Steve, K9DCI Article: 94598 of rec.radio.amateur.homebrew From: hexter@blazenet.net (Gudmundur) Subject: power formula for vswr? Date: Mon, 17 Oct 2005 21:41:33 -0000 Message-ID: <11l86kdffmec9c1@corp.supernews.com> If I know only the power in dbm is there a formula to arrive at vswr without conversion first to watts or volts? outbound = +63dbm (2kw) reflected = +36dbm (4w) This is a waveguide system with a dummyload connected in the event the numbers seem improper. I would like to use the formula when we connect the real antenna. Article: 94599 of rec.radio.amateur.homebrew From: =?ISO-8859-2?Q?Pawe=B3_Stobi=F1ski?= Subject: Re: power formula for vswr? Date: Tue, 18 Oct 2005 00:03:43 +0200 Message-ID: References: <11l86kdffmec9c1@corp.supernews.com> Gudmundur wrote: > If I know only the power in dbm is there a formula to arrive at > vswr without conversion first to watts or volts? > > outbound = +63dbm (2kw) > reflected = +36dbm (4w) > Take the formula for calculating vswr from P in watts, previously converting the dBm into W. You'll get the following vswr=(1+10^(0.5*(Pout-Pref)))/(1-10^(0.5*(Pout-Pref))). Regards, Paweł Stobiński, SQ9NRY Article: 94600 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Choice of iron powder toriod? References: <3B74f.437160$x96.227112@attbi_s72> Message-ID: Date: Tue, 18 Oct 2005 02:15:08 GMT Hello Bill, > Hello Joerg, nice to meet you for the first time. > Likewise. You name sounds very familiar, IIRC from a book about design of HF gear. Didn't you work at Collins in the good old days when they had mechanical filters in their gear? Regards, Joerg http://www.analogconsultants.com Article: 94601 of rec.radio.amateur.homebrew From: "William E. Sabin" References: <3B74f.437160$x96.227112@attbi_s72> Subject: Re: Choice of iron powder toriod? Message-ID: Date: Tue, 18 Oct 2005 09:09:00 GMT Yes. I started at Collins Radio engineering department in 1964 and retired >from Rockwell Collins in 1990. For more info search Google for my name and my call sign. See QRZ.COM for W0IYH. See www.noblepub.com. Bill W0IYH "Joerg" wrote in message news:MUY4f.1931$dO2.1625@newssvr29.news.prodigy.net... > Hello Bill, > >> Hello Joerg, nice to meet you for the first time. >> > > Likewise. You name sounds very familiar, IIRC from a book about design of > HF gear. Didn't you work at Collins in the good old days when they had > mechanical filters in their gear? > > Regards, Joerg > > http://www.analogconsultants.com Article: 94602 of rec.radio.amateur.homebrew Message-ID: <4354FDA4.196B67C2@earthlink.net> From: "Michael A. Terrell" Subject: Re: Choice of iron powder toriod? References: <3B74f.437160$x96.227112@attbi_s72> Date: Tue, 18 Oct 2005 13:49:48 GMT "William E. Sabin" wrote: > > Yes. I started at Collins Radio engineering department in 1964 and retired > from Rockwell Collins in 1990. For more info search Google for my name and > my call sign. See QRZ.COM for W0IYH. See www.noblepub.com. > > Bill W0IYH Did you ever work on their microwave receiver designs? -- ? Michael A. Terrell Central Florida Article: 94603 of rec.radio.amateur.homebrew From: "William E. Sabin" References: <3B74f.437160$x96.227112@attbi_s72> <4354FDA4.196B67C2@earthlink.net> Subject: Re: Choice of iron powder toriod? Message-ID: Date: Tue, 18 Oct 2005 14:48:47 GMT Hello, Mike, I had a little experience with some military L-band RF design (JTIDS), but that is about all. I have also designed miniature lumped-element filters for the 3 GHz region. But most of my work and also my ham radio experience have been at HF. Also, I am mostly, but not entirely, an analog specialist, which has put me somewhat into the Jurassic Age. Bill W0IYH "Michael A. Terrell" wrote in message news:4354FDA4.196B67C2@earthlink.net... > "William E. Sabin" wrote: >> >> Yes. I started at Collins Radio engineering department in 1964 and >> retired >> from Rockwell Collins in 1990. For more info search Google for my name >> and >> my call sign. See QRZ.COM for W0IYH. See www.noblepub.com. >> >> Bill W0IYH > > > Did you ever work on their microwave receiver designs? > > -- > ? > > Michael A. Terrell > Central Florida Article: 94604 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Choice of iron powder toriod? References: <3B74f.437160$x96.227112@attbi_s72> <4354FDA4.196B67C2@earthlink.net> Message-ID: <3F95f.2019$dO2.694@newssvr29.news.prodigy.net> Date: Tue, 18 Oct 2005 16:45:51 GMT Hello Bill, > ... Also, I am mostly, but not entirely, an analog specialist, > which has put me somewhat into the Jurassic Age. > Not really. Newly minted engineers know remarkably little about analog techniques. Yet at the beginning and the end of circuits stuff usually needs to connect to the analog world. So don't be surprised when someone begs you to do just one more stint when you are past 90. Then again a SW engineer once told me that nothing is truly analog. There is always that smallest digital step, the quantum. Regards, Joerg http://www.analogconsultants.com Article: 94605 of rec.radio.amateur.homebrew From: John - KD5YI Subject: Re: power formula for vswr? References: <11l86kdffmec9c1@corp.supernews.com> Message-ID: Date: Tue, 18 Oct 2005 19:42:00 GMT Paweł Stobiński wrote: > Gudmundur wrote: > >> If I know only the power in dbm is there a formula to arrive at >> vswr without conversion first to watts or volts? >> >> outbound = +63dbm (2kw) >> reflected = +36dbm (4w) >> > > Take the formula for calculating vswr from P in watts, previously > converting the dBm into W. > You'll get the following > vswr=(1+10^(0.5*(Pout-Pref)))/(1-10^(0.5*(Pout-Pref))). > > > Regards, > Paweł Stobiński, SQ9NRY SWR = -1? Article: 94606 of rec.radio.amateur.homebrew From: =?ISO-8859-2?Q?Pawe=B3_Stobi=F1ski?= Subject: Re: power formula for vswr? Date: Tue, 18 Oct 2005 22:41:55 +0200 Message-ID: References: <11l86kdffmec9c1@corp.supernews.com> John - KD5YI wrote: > SWR = -1? Right, a little oversight. Swap Pout for Pref. Regards, Paweł Stobiński, SQ9NRY Article: 94607 of rec.radio.amateur.homebrew From: Joerg Subject: Re: Choice of iron powder toriod? References: <3B74f.437160$x96.227112@attbi_s72> <4354FDA4.196B67C2@earthlink.net> <43555560.1FB470CD@earthlink.net> Message-ID: Date: Tue, 18 Oct 2005 23:55:53 GMT Hello Michael, > There is no reason to apologize for being good with analog. ;-) I > worked as a broadcast engineer during the time they announced the first > memory chip, (1101) which was a slow, noisy 256 bit * 1 DRAM with very > critical timing. I also did analog and digital work on the microwave > equipment built at Microdyne, before L3-Com closed the Ocala plant. > Seems you started with digital stuff a year or two earlier than I did. My first RAM had a whopping 1024 bits. Not bytes, bits. 21...something, I could look it up since the device where its in still works. > The reason I asked about the microwave equipment, I would like to > meet the people who designed the C-band CATV receivers I had to maintain > in the '80s. I always loved Collins equipment, till I ran into those > radios. They had a horrible failure rate, ... But their HF radios were quite reliable. Unfortunately at that time out of my budget range, and so were those nice mechanical filters :-( Regards, Joerg http://www.analogconsultants.com Article: 94608 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <1129680664.582016.285580@f14g2000cwb.googlegroups.com> Subject: Re: poor man's network analyzer ?? Message-ID: <6Hg5f.4577$t12.3547@trnddc03> Date: Wed, 19 Oct 2005 00:45:54 GMT "john w." wrote in message news:1129680664.582016.285580@f14g2000cwb.googlegroups.com... > > Looking for suggestions / construction articles on how to make a "poor > man's network analyzer" for the HF frequency range by using either an > I/Q demodulator chip or else a precision phase & gain measuring chip > like the AD8302. > > I would swear that I had seen an article on this topic someplace, about > a year ago. But I've lost the article, and I just spent several hours > of fruitless Internet searching. > > Thanx in Advance! john w. > See the Kanga site for the W7ZOI analyzer: http://www.bright.net/~kanga/kanga/w7zoi/products/spectrum_analyzer.htm W4OP Article: 94609 of rec.radio.amateur.homebrew Message-ID: <4355A812.CB7B0BEB@earthlink.net> From: "Michael A. Terrell" Subject: Re: Choice of iron powder toriod? References: <3B74f.437160$x96.227112@attbi_s72> <4354FDA4.196B67C2@earthlink.net> <43555560.1FB470CD@earthlink.net> Date: Wed, 19 Oct 2005 01:56:38 GMT Joerg wrote: > > Hello Michael, > > > There is no reason to apologize for being good with analog. ;-) I > > worked as a broadcast engineer during the time they announced the first > > memory chip, (1101) which was a slow, noisy 256 bit * 1 DRAM with very > > critical timing. I also did analog and digital work on the microwave > > equipment built at Microdyne, before L3-Com closed the Ocala plant. > > > > Seems you started with digital stuff a year or two earlier than I did. > My first RAM had a whopping 1024 bits. Not bytes, bits. 21...something, > I could look it up since the device where its in still works. 2114? 1K * 4 bits? > > The reason I asked about the microwave equipment, I would like to > > meet the people who designed the C-band CATV receivers I had to maintain > > in the '80s. I always loved Collins equipment, till I ran into those > > radios. They had a horrible failure rate, ... > > But their HF radios were quite reliable. Unfortunately at that time out > of my budget range, and so were those nice mechanical filters :-( > > Regards, Joerg > > http://www.analogconsultants.com I still have an unused 2.1 KHz Collins 455 KHz mechanical filter I bought at the Dayton hamfest years ago. Its a little narrow for voice, but it would be good for CW. I still like Collins equipment, just not their poorly designed CATV equipment. I wish I could afford a R-390 and felt well enough to do a complete restoration. :( -- ? Michael A. Terrell Central Florida Article: 94610 of rec.radio.amateur.homebrew From: "Tim Williams" References: <3B74f.437160$x96.227112@attbi_s72> <4354FDA4.196B67C2@earthlink.net> <3F95f.2019$dO2.694@newssvr29.news.prodigy.net> Subject: Re: Choice of iron powder toriod? Message-ID: Date: Tue, 18 Oct 2005 21:47:01 -0500 "Joerg" wrote in message news:3F95f.2019$dO2.694@newssvr29.news.prodigy.net... > Then again a SW engineer once told me that nothing is truly analog. > There is always that smallest digital step, the quantum. So, digital is base two, and analog is base 1.6 x 10^19? ;-) Tim -- Deep Fryer: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms Article: 94611 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <1129680664.582016.285580@f14g2000cwb.googlegroups.com> <181020051927067964%artie.m@gmail.com> Subject: Re: poor man's network analyzer ?? Message-ID: Date: Wed, 19 Oct 2005 03:25:39 GMT "artie" wrote in message news:181020051927067964%artie.m@gmail.com... > In article <1129680664.582016.285580@f14g2000cwb.googlegroups.com>, > john w. wrote: > >> Looking for suggestions / construction articles on how to make a "poor >> man's network analyzer" for the HF frequency range by using either an >> I/Q demodulator chip or else a precision phase & gain measuring chip >> like the AD8302. >> >> I would swear that I had seen an article on this topic someplace, about >> a year ago. But I've lost the article, and I just spent several hours >> of fruitless Internet searching. >> >> Thanx in Advance! john w. >> > > Vector network analyzer: > > http://www.tapr.org/kits_vna.html?PHPSESSID=a7dc69d72fed0dac75d27069f244 > 0fa7 > > Or, if you can't hack fine-pitch boards, you can buy it assembled and > tested: ($655) > > http://radio.tentec.com/Amateur/vna > Not as good as the Agilent box I have in the lab, but the Agilent box > costs more than my car... > > -- > Namaste-- And not nearly as good as the N2PK VNA: http://users.adelphia.net/~n2pk/ W4OP Article: 94612 of rec.radio.amateur.homebrew From: "Ecureil Affamé" Subject: "Miss Moskita" who hurts me... Date: Wed, 19 Oct 2005 11:06:38 +0200 Message-ID: <43560bf9$0$978$8fcfb975@news.wanadoo.fr> HI, I'm building a 40m rig, using the transmitter part of the "Miss Moskita" . (German rig "QrpProject" : NE602-BF199-BFR96-2SC1969). Unfortunately, it doesn't work. I spent a lot of time ( 2 months) to find the mistake without any result. At last, I changed ALL the parts of the circuit without result. Could someone give me the voltage I should have at (DC and peak/peak). NE602 pin 1 (I have 50mVpp 12mHz) NE602 pin 6 (I have 0.6Vpp 4.91mHz) NE602 pin 4-5 (I have 0.2V pp 7mHz...) Base BF199 (I have 25mVpp and 0.75VDC) Base BFR96 (I have 1.2Vpp) Collector BFR96 (I have 10Vpp and 8VDC) Base 2SC1969 ( I have 2V pp) I'm very tired...;o( Thanks a lot for your help. Dan Article: 94613 of rec.radio.amateur.homebrew From: Keith Williams Subject: Re: Choice of iron powder toriod? Date: Wed, 19 Oct 2005 10:55:07 -0400 Message-ID: References: <3B74f.437160$x96.227112@attbi_s72> <4354FDA4.196B67C2@earthlink.net> <3F95f.2019$dO2.694@newssvr29.news.prodigy.net> In article , tmoranwms@charter.net says... > "Joerg" wrote in message > news:3F95f.2019$dO2.694@newssvr29.news.prodigy.net... > > Then again a SW engineer once told me that nothing is truly analog. > > There is always that smallest digital step, the quantum. > > So, digital is base two, and analog is base 1.6 x 10^19? ;-) Not really. Analog's bits are just smaller. ;-) -- Keith