Article: 94488 of rec.radio.amateur.homebrew From: Dr. Anton T. Squeegee Subject: Re: WTD: Powerpole 180A Connectors Date: Sat, 1 Oct 2005 21:15:31 -0700 Message-ID: References: In article , w1ksz@earthlink.net says... > The Glenayre Power Supply I got with it's companion Amp uses 180A > Powerpole Connectors for the 28 vdc output. Anyone got a spare couple > of these beasties ?? Even better would be the interconnecting power > cable, there are two ~1/4" pins for the +DC and two ~1/4" jacks for > the -DC. I found a GR double plug fits the -DC, but the +DC has me > stumped. I hate to tack solder a lead on them (too tacky !!). Are you referring to Anderson Power Products, specifically their 'MultiPole' line as shown here? http://www.andersonpower.com/products/mp/mp.html The connectors themselves can be had through Allied Electronics. Take a look at this link. http://www.alliedelec.com/Search/SearchResults.asp? SearchQuery=Anderson+Power&Submit=find+it%21 Keep in mind, though, that you'll need a specialized (and expensive -- $200 at least) heavy-gauge crimping tool to deal with the heavy-gauge contacts. If you can't get hold of the appropriate tool (Greenlee makes a very nice hex crimper -- it looks like a big pair of garden shears, but with crimp dies instead of blades), I can offer small-scale assembly services at a cheap rate ($40/hour, half-hour minimum, see my web site, etc.) Happy hunting. -- Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute. (Known to some as Bruce Lane, ARS KC7GR, kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com "If Salvador Dali had owned a computer, would it have been equipped with surreal ports?" Article: 94489 of rec.radio.amateur.homebrew From: "PeteDBNZA" Subject: Re: sig gen plans Date: Sun, 2 Oct 2005 13:02:54 +0200 Message-ID: References: <1128220180.879138.46200@z14g2000cwz.googlegroups.com> Hi Guys, If you are not in continental US or one of it's regions, you will pay MUCH more than $20 for shipping alone! Build, therfore, becomes an option. My 2c. -- Pete . . ZS5ACT http://www.electronic-ideas.com/zs5act/ BTW I HATE bottom posters with passion! ------ Reply Separator ------ wrote in message news:1128220180.879138.46200@z14g2000cwz.googlegroups.com... > Matt, for many of us building a piece of test equipment that we can > inexpensively buy used on eBay is much like wanting to build a pair of > pliers or a screwdriver from scratch. It's simply not worth the time > and expense. > > I use a simple Heatkit r.f. signal generator that I purchased on eBay, > and paid something like $12 for it less shipping. It performs every > function I need. If I could even find the need components to build it > today, they alone would cost me far more than $20. > > Take this for whatever it's worth. > > Harry C. > Article: 94490 of rec.radio.amateur.homebrew From: "W3JDR" References: <1128220180.879138.46200@z14g2000cwz.googlegroups.com> Subject: Re: sig gen plans Message-ID: Date: Sun, 02 Oct 2005 12:32:36 GMT ...the group IS called "rec.radio.amateur.homebrew"..isn't it?. Why would someone be advised to buy when he asks for advice in a group dedicated to building??? Joe "PeteDBNZA" wrote in message news:dhoeos$82t$1@ctb-nnrp2.saix.net... > Hi Guys, > If you are not in continental US or one of it's regions, you will pay MUCH > more than $20 for shipping alone! > > Build, therfore, becomes an option. > > My 2c. > > -- > Pete . . > ZS5ACT > http://www.electronic-ideas.com/zs5act/ > > BTW I HATE bottom posters with passion! > > ------ Reply Separator ------ > > wrote in message > news:1128220180.879138.46200@z14g2000cwz.googlegroups.com... >> Matt, for many of us building a piece of test equipment that we can >> inexpensively buy used on eBay is much like wanting to build a pair of >> pliers or a screwdriver from scratch. It's simply not worth the time >> and expense. >> >> I use a simple Heatkit r.f. signal generator that I purchased on eBay, >> and paid something like $12 for it less shipping. It performs every >> function I need. If I could even find the need components to build it >> today, they alone would cost me far more than $20. >> >> Take this for whatever it's worth. >> >> Harry C. >> > > Article: 94491 of rec.radio.amateur.homebrew From: novatech@eskimo.com (Steven Swift) Subject: Re: sig gen plans Date: 2 Oct 2005 16:25:41 GMT Message-ID: References: <1128220180.879138.46200@z14g2000cwz.googlegroups.com> "W3JDR" writes: >...the group IS called "rec.radio.amateur.homebrew"..isn't it?. Why would >someone be advised to buy when he asks for advice in a group dedicated to >building??? >Joe And it is fund to build stuff. The old sig gens were pretty simple, with most of the hard work on the dial. The Eico 320 was pretty popular and you can use the manual to build one of your own: http://www.nostalgiaair.org/References/Manuals/EIC/EIC_8.zip But you can replace the triodes with fets, lower the voltage to 12 volts and get the same results. Steve. -- Steven D. Swift, novatech@eskimo.com, http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA Article: 94492 of rec.radio.amateur.homebrew From: Win Subject: SB-220 Parts Date: Sun, 02 Oct 2005 12:06:54 -0500 Message-ID: <2m40k15o02mrgrkt0hn98qo0vt6aedha5h@4ax.com> Looking for the second wafer, for the band switch of an SB-220, Heath # 21 63-562. Any ideas? Win, w0lz Article: 94493 of rec.radio.amateur.homebrew From: "xpyttl" References: <1128220180.879138.46200@z14g2000cwz.googlegroups.com> Subject: Re: sig gen plans Message-ID: <2LV%e.851$Yv6.364@fe06.lga> Date: Sun, 2 Oct 2005 14:34:36 -0400 A lot of the modern signal generator projects are based on the Analog Devices AD9850. Analog Devices actually encourages hams to use their sample service, so the part itself is no problem. It is relatively simple to program, so you may choose the microcontroller of your choice, although most of the projects out there seem to lean toward the PIC. The challenge could well be the circuit board. The 9850 is only available in TSSOP so you need a good quality circuit board to attach it to. If your PCB skills are good this won't be a problem. But if not, you might need to hunat around for a protoboard or something of that ilk that you can get in your location. Unfortunately, these tend to be kind of pricey. .. "Steven Swift" wrote in message news:dhp1m5$fdv$1@eskinews.eskimo.com... > "W3JDR" writes: > >>...the group IS called "rec.radio.amateur.homebrew"..isn't it?. Why would >>someone be advised to buy when he asks for advice in a group dedicated to >>building??? > >>Joe > > And it is fund to build stuff. The old sig gens were pretty simple, with > most of the hard work on the dial. The Eico 320 was pretty popular and > you can use the manual to build one of your own: > http://www.nostalgiaair.org/References/Manuals/EIC/EIC_8.zip > > But you can replace the triodes with fets, lower the voltage to 12 volts > and > get the same results. > > 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: 94494 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Preamp Message-ID: <8c01k1tt0g55l5eh49bb1ivv48vdf73s98@4ax.com> References: Date: Mon, 03 Oct 2005 01:09:33 GMT I put your tirade on the end of this as it's not relevant to the orininal question. First: the question, reread please. The question was a about bandwidth of a wide band amp and noise figure. Overload performance was NOT addressed. If it were the first thing would be to rid oneself of those diodes. A good device will usually withstand more than the diodes (U310 fet in common base amp I've used for Preamp took 25watts before expiring as a test!). However I do not need you lesson on that either. I design and build both professionally and as a ham VHF op. My experience includes one idiot that runs a KW onto a M2 7 element 800ft from me to work local repeaters! On an average day I have between +10-20DBm of rf comming fown the coax when hes operating. I know more than you suspect or even checked about working in a RF rich environment, about 35years of experience in landmobile plus commercial. Now if you can address the question of amp bandwidth and noise figure and diodes we can help this person. NOT drag the topic off into the woods. Further I happen to have posted at the same time as Tim and was not contradicting him or addressing him. I was answering the author of the thread. Allison On Sun, 02 Oct 2005 15:30:52 -0400, TRABEM <> wrote: >NO NO NO NO NO............... > >LISTEN to TIM!!!!!!!!!!!!! Tim is correct, you are WRONG. > >While the diodes might be benign in the presence of small and medium >sized out of band signals, they do exactly what Tim said in the >presence of large input signals like you might find near transmitters. >Remember, the 200 KW FM broadcast station at the end of the block, or >the 5 KW AM broadcast band transmitter down the road from you. Even >though these signals are no where near the frequency you are trying to >listen to, the diodes will see them and act as a non linearity and >produce IMD all throughout the radio spectrum. > >Remember, these diodes are not protected by a frequency selective >tuned circuit.....so any big signal that comes down the antenna is >gonna make a problem for you , especially if you're trying to listen >to a weak signal. > >Tim is correct. > >Years ago I was working for a tv station as a chief engineer. I had to >oversee the installation of the new 900 foot tower and make sure the >tower monkeys aligned the dish properly for the STL. So, I spent quite >a few days at the site. The guys putting up the antenna had just >purchased new ICOM HT's and had them modified for out of band >operation so they could use them for communication between the tower >people and the ground crew running the wench. > >I told them I had the same radio as they did, (which was true). When I >showed them my radio, there were no odd audio sounds coming out of the >speaker. When they turned on their radios, all they could hear was the >overload from the FM station sharing the same tower. > >The owner of the tower company was a ham and modified the ICOM's with >back to back diodes at the antenna to keep the front ends from blowing >out because they often worked within 10 or 20 feet of big powerful >antennas. He told me without the diodes he added, he would lose one >radio per day to rf overload and he used to carry spare front end >transistors. Part of his evening ritual was to sit down and remove the >blown front end transistors and replace them. He had done it so many >times he could do it in 5 minutes! But, after he put the diodes in, >the front end didn't blow anymore....but they always had interference >from other transmitters as a result of the diode mod! > >He learned the hard way not to introduce non linearities before the >front end tuned circuits! I think you need the same lesson Allison. > >I took one of his radios home that evening and modified it. I >basically removed the gasfet front end transistor and threw his back >to back diodes in the trash. I added a 10 db pad to attenuate the >incoming signals across the entire spectrum. They spent about 3 weeks >doing the tower job, and by the end of the job, I had modified all his >radios. They never had another interference problem and they never >lost a single front end. The owner was a good guy and offered to pay >me dearly for tweaking his radios. > >With all due respect, the diode capacitance is IS NOT the problem. >It's the non linearities associated with the rectification in the >presence of big out of band signals. > >Listen to Tim, he's telling you the truth! > >T > > >>The diode capaitance is low and really not a factor in preamp gain or >>noise. They are non conducting and the capacitance is easily absorbed >>into fees and matching systems. >> Article: 94495 of rec.radio.amateur.homebrew From: mcalhoun@ksu.edu Subject: How to feed a long half-square? Date: 2 Oct 2005 21:54:27 -0500 Message-ID: I have room to erect a "half square" (aka upside-down phased verticals?) 20-meter antenna to be fed at one corner (low-impedance location; attach 50-ohm coax) or at the bottom (high-impedance; use a matching network): A B +--------------+ 1/2wave long | /| 1/4wave high | / | / Matching Network Coax Unfortunately, I do NOT (because my house is in the way) have room to make it a more-balanced curtain: A B C +--------------+--------------+ | /| | | / | | / coax However, if I skip the middle "vertical", I have room for four vertical sections in a space that should have five: A B C D E +--------------+--------------+--------------+--------------+ | | this part will be about | | | | 10 feet above the peak | | of my house FWIW, line ABCDE will be about 30 feet above ground. I've never done any antenna modeling, and I've never had any "feel" for antenna phasing (EE degree notwithstanding), but I suspect feeding it at the original corner (B) will result in somewhat unbalanced currents almost everywhere. QUESTION: Is there any not-too-difficult way to feed it at point C, especially without a lot of cut-and-try (since a lot of tree- and ladder-climbing will be involved)? What about, for example, bringing x-wavelengths of coax BC and CD to a common point somewhere above ground level (my shack is in the basement) and connect them with a T to the coax that goes through the wall to the rig? What lengths? -- --Myron A. Calhoun. Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) Article: 94496 of rec.radio.amateur.homebrew From: "xpyttl" References: <1128220180.879138.46200@z14g2000cwz.googlegroups.com> <2LV%e.851$Yv6.364@fe06.lga> Subject: Re: sig gen plans Message-ID: Date: Mon, 3 Oct 2005 08:01:42 -0400 "John Miles" wrote in message news:MPG.1daa35dbbac7e0109896ef@news-central.giganews.com... > Which is something I can't begin to understand. With the AVRs, you get > a faster chip with an industrial-strength C/C++ compiler that also > happens to be free (as in beer). Well, there are a couple of things here. First of all, Microchip was early to the game. As a result, there is a lot of tutorial information out there. Admittedly, a lot of it is really bad, but it's existence helps people get over the hump. And lets face it, deploying a microcontroller really isn't very hard, but getting over the initial fear is. The huge number of PIC projects out there helps people feel like maybe it isn't so hard. A second part is the really wonderful simulation capabilities of MPLAB. It makes it pretty darned easy to see what is going on, and when people are starting out, that is a pretty big deal. If you look at the hobbyist project code out there, it looks like 90% or more of them are written by people "just starting out". Thirdly is the availability of cheap programmers. Yes, I know the AVR is even simpler to program than the PIC, but it hasn't drawn literally hundreds of programmer designs, almost all of which can be built cheaply. This is another consequence of Microchip being early to the game. And actually, I think an advantage the PIC has is that, at least for the 16F PICs, all the C compilers are truly horrid. When you are going to deploy a microcontroller, any microcontroller, you really need to understand what is happening at a pretty basic level. Once you have a lot of expertise in a particular part, then a compiler can be a big productivity boost. But until you have a lot of expertise, the compiler can really get in the way. Fortunately for the PIC community, most of the compilers are bad enough that you're not real tempted to use them. > Actually the AD9850 comes in a SOIC package with 20 pins/inch, or half > the spacing of a normal DIP IC, rather than a TSSOP (0.5 mm lead pitch, > or about 50 pins/inch). I've never seen a 9850 in an SOIC. That certainly would be easier to use. Where did you find such a thing? When I check AD's web site, all I see is a choice whether I want my SSOP's on a reel or not. .. Article: 94497 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Preamp Message-ID: References: <8c01k1tt0g55l5eh49bb1ivv48vdf73s98@4ax.com> Date: Mon, 03 Oct 2005 14:46:12 GMT On Mon, 03 Oct 2005 00:13:54 -0400, TRABEM <> wrote: >On Mon, 03 Oct 2005 01:09:33 GMT, nospam@nouce.bellatlantic.net wrote: > >>I put your tirade on the end of this as it's not relevant to the >>orininal question. >> > >The original post (by A*s*i*m*o*v) mentioned back to back diodes as >protection, so my reply was quite relevant. If it was about overload yes. It was about bandwidth and noise. > >Not sure what ruffled your feathers so badly Allison. But, whatever it >was, I am sorry if I did something that didn't meet with your >approval. You really came in with and attitude. but completely missed the real subject of the question. >I also worked professionally as an avionics tech, and was in the >business when the first Motorola commercial repeaters using >synthesizers were put up...and they wondered why the other repeaters >on the same tower couldn't hear well. That only took 'em about 10 >years to figure out. Then, about 10 years after that, they started >using gasfets, and it took them another 10 years to figure out they >didn't do well in high rf fields. By then, it was the 1980's.....but >at least they got it right eventually. We are talking presynth. I had my First Class before that. My first commercial UHF repeater was built from U44 components then later Motrac as they were current radios For 1971-2 that was pretty good. The motrac front ends were 6 cavitys a mixer then IF selectivity, crunchproof. LO was always a crystal for least phase noise. Anyone that read papers by Rhode understood this in the early to mid 70s. >Maybe you designed some of those early nightmarish radios yourself? I take that as insult. ;) Gads no, I thought they were crap too. I'm not all that thrilled with the ARC308C or worse 324 and the put them in planes. I know that as I have a 308 as backup. Gag, Ick, ick. but at 1500 to 2k for a new one I'll keep it till it quits. >Anyway, I wish you luck. And hope you realize the importance of >keeping the front end clean, which sometimes means dumping the gasfet >and using a bipolar preamp instead. Your being pendantic again. I'm not big on gasfets untill I get above 1GHz. At 6m a u310 bipolar fet in common base gets me about 12db. With a good IP and noise figure. Just enough to get past the image stripping filter before the Level-7 DBM. That makes for a nice crunchproof frontend that with sub 3db noise figure. If I could get that noise figure without the fet I'd not use it but I need the gain. I've tried mrf571 in a norton push pull configuration, hard to overload but the 100ma standing current was hard to take for portable ops! If your interested, ops here are QRP weak signal 6m SSB and 2M ssb and occasionally CW using solar power and battery. Power consumption is a consideration as well as perfomance. Overload performance with a KW 800ft away and in band is well challenging. The challenge is to get enough gain to ovecome the mixer noise without having a watt of power at the mixer. >Actually, I hope the original poster (A*s*i*m*o*v) got the message >about introducing gross non linear back to back diodes across the >antenna terminals. That is true. However think about it for more than a second. Diodes or not hes talking about gain, bandwidth and noise so even without the diodes hes already running wide and risking overload at the next stage. Without selectivity you get cascade overload. The classic problem of weak reciever fix of stacking gain before it and watching the input overload threshold wander in to the -40dbm (or worse) region. Bad way to fix the problem. Allison KB1GMX Article: 94498 of rec.radio.amateur.homebrew From: "Asimov" Subject: Re: Preamp Message-ID: References: Date: Mon, 03 Oct 2005 16:11:05 GMT "TRABEM" bravely wrote to "All" (03 Oct 05 00:13:54) --- on the heady topic of "Re: Preamp" TR> From: TRABEM <> TR> Xref: core-easynews rec.radio.amateur.homebrew:88137 TR> On Mon, 03 Oct 2005 01:09:33 GMT, nospam@nouce.bellatlantic.net wrote: >I put your tirade on the end of this as it's not relevant to the >orininal question. > TR> The original post (by A*s*i*m*o*v) mentioned back to back diodes as TR> protection, so my reply was quite relevant. [,,,] TR> Actually, I hope the original poster (A*s*i*m*o*v) got the message TR> about introducing gross non linear back to back diodes across the TR> antenna terminals. TR> Have fun. I have followed both your points with great interest. My guess is that the diodes are benign in a weak signal area. I expect the original design used them more for static rather than for overload protection because the input was intended to expect microvolt levels. My choice would be not to use anti-parallel diodes in a design but this is what I found in the circuit so some engineer thought about it enough to use them. I would have preferentially used a reverse biased diode across the active device's junction because it is usually the reverse polarity in a pulse that damages a junction. In this question I was more interested on the effect of the protection diodes' capacitance because as you know it is greatest at zero bias. This wideband pre-amp's input stage uses feedback to define the input impedance and the diodes' capacitance is at the node point, so I wondered if there was little effect. As you know, in an inverter the node point is ideally a voltage null. Thank you both for the great debate! A*s*i*m*o*v ... As I suspected, you're a rank sentimentalist! --Cpt. Louis Renault Article: 94499 of rec.radio.amateur.homebrew From: nomail@spam.me.not.org (David Hatch) Subject: Re: solder paste for SMT? Date: 3 Oct 2005 17:02:30 GMT Message-ID: References: TRABEM <> wrote in : >On Sun, 02 Oct 2005 17:14:27 -0400, maxfoo wrote: > >>On Sun, 02 Oct 2005 14:57:28 -0400, TRABEM <> wrote: >> >>>If someone would make an inexpensive dispenser for distributing the >>>paste evenly, I think the paste would be viable for soldering and for >>>rework. Without a means to dispense small quantities of paste on >>>demand, the paste method is truly useless (IMHO). >> I use DigiKey #K439-ND dispenser tips with 0.016" hole. They screw onto the end of the paste syringe. Works great. I don't hot-air refow, but it allows for a small-volume dispense. My technique is to run a bead down the center of the row of pins, and then heat each pin briefly, or all at once if I have a proper tip for my Metcal station. The solder wicks up to the pins, and there's maybe one bridge on a 48-pin TSSOP. Done it for years this way. -- David Hatch KR7DH Article: 94500 of rec.radio.amateur.homebrew From: nospam@nouce.bellatlantic.net Subject: Re: Preamp Message-ID: References: Date: Mon, 03 Oct 2005 17:50:39 GMT On Mon, 03 Oct 2005 16:11:05 GMT, "Asimov" wrote: >My choice would be not to use anti-parallel diodes in a design but this >is what I found in the circuit so some engineer thought about it enough >to use them. I would have preferentially used a reverse biased diode >across the active device's junction because it is usually the reverse >polarity in a pulse that damages a junction. Generally a good design and a robust device will be tougher than the diodes frequenty used. For example I've found JFETS will easily stand 40+volts on the gate before failing, MOSFETS (dual gate 3n200 types and BFR998) 60-80V were needed to kill them. Even a lowly 2n5176 bipolar will be grossly overloaded in a wide band amp before possibility of destruction. Remember .5V PP (I'll assume silicon diodes) is at or around -1 to 0DBm. Thats one milliwatt of RF. the real issue is with wide band signals you can have multiple signals within the bandwidth that at some point in the cycle are additive and as we've all said those diodes will do bad things under those conditions. >In this question I was more interested on the effect of the protection >diodes' capacitance because as you know it is greatest at zero bias. >This wideband pre-amp's input stage uses feedback to define the input >impedance and the diodes' capacitance is at the node point, so I >wondered if there was little effect. As you know, in an inverter the >node point is ideally a voltage null. The capacitance if of limited significance. Its' effects will be tempered by topology and impedences at the point of use. As pointed out, they must not see conduction or "bad things happen". _IF_ you really must protect the input with diodes put a healthy (6-12V) of reverse bias on them. That should adequately protect the first device but still absorb transients. For instrumentation applications (high impedence) they are a commonplace thing as the source could be anything or known. For RF use I tend to leave them out as most devices once in circuit are robust as is. And usually uf there is an event big enough to fry the device then protection diodes are just two more fried devices. One exception: series diodes on the supply for reverse polarity protection and Zeners(or transzorbs) on the supply for overvoltage protection. Often destruction didn't come down the antenna but in the back door via the power or other control lines. >Thank you both for the great debate! As in most electronics there are subtle and gross effects. Being aware of both are of importance. Hope it helps. Allison KB1GMX Article: 94501 of rec.radio.amateur.homebrew From: Straydog Subject: Re: How to feed a long half-square? Date: Wed, 5 Oct 2005 10:04:31 -0400 Message-ID: References: Its pretty hard to make recommendations without knowing, besides your driven element conductor and proposed feedline, what other conducting elements are nearby (housewiring, power lines, metal fences, metal plumbing, etc.). The simplest and fastest approach would be to hook up whatever you have, match it with an antenna tuner to your rig, and get on the air and see if you can make contacts and ask what your signal report is. Usually, if you can hear stations and the S meter is somewhere in the middle of the scale, then they should hear you. You can tweak, adjust, improve from that point on (and assess your TVI, BCI, and other interference problems, too). ===== no change to below, included for reference and context ===== On Sun, 2 Oct 2005, mcalhoun@ksu.edu wrote: > I have room to erect a "half square" (aka upside-down phased verticals?) > 20-meter antenna to be fed at one corner (low-impedance location; attach > 50-ohm coax) or at the bottom (high-impedance; use a matching network): > > A B > +--------------+ 1/2wave long > | /| 1/4wave high > | / | > / Matching Network > Coax > > Unfortunately, I do NOT (because my house is in the way) have room > to make it a more-balanced curtain: > > A B C > +--------------+--------------+ > | /| | > | / | | > / > coax > > However, if I skip the middle "vertical", I have room for four vertical > sections in a space that should have five: > > A B C D E > +--------------+--------------+--------------+--------------+ > | | this part will be about | | > | | 10 feet above the peak | | > of my house > > FWIW, line ABCDE will be about 30 feet above ground. > > I've never done any antenna modeling, and I've never had any "feel" for > antenna phasing (EE degree notwithstanding), but I suspect feeding it > at the original corner (B) will result in somewhat unbalanced currents > almost everywhere. > > QUESTION: Is there any not-too-difficult way to feed it at point C, > especially without a lot of cut-and-try (since a lot of > tree- and ladder-climbing will be involved)? > > What about, for example, bringing x-wavelengths of coax BC and CD to a > common point somewhere above ground level (my shack is in the basement) > and connect them with a T to the coax that goes through the wall to > the rig? What lengths? > -- > --Myron A. Calhoun. > Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge > PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448 > NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol) > Article: 94503 of rec.radio.amateur.homebrew From: James Skalski Subject: wtb 8122 matched set Message-ID: <9QU0f.1629$OL5.946@trndny05> Date: Wed, 05 Oct 2005 18:20:53 GMT I need a pair of the above tubes. Good used ok. Burle or Eimac preferred. Jim n2go Article: 94504 of rec.radio.amateur.homebrew From: Joerg Subject: Re: epoxy instead of solder? References: Message-ID: Date: Wed, 05 Oct 2005 21:45:16 GMT Hello John, > 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? > Then there is the stench that most epoxies let off. Mostly of the not so healthy kind. Regards, Joerg http://www.analogconsultants.com Article: 94505 of rec.radio.amateur.homebrew From: Dr. Anton T. Squeegee Subject: Re: epoxy instead of solder? Date: Wed, 5 Oct 2005 21:18:13 -0700 Message-ID: References: In article , TRABEM <> says... > 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:>: Not really. Consider the angle of serviceability. It's easy enough to use a 'HoTweezer' station to replace a bad chip component secured with solder. It's darn near impossible to replace the same component if secured with Epoxy. Also, I'm not convinced that "conductive" Epoxy really is. I'd want to see some real numbers on resistance per cm/squared on the stuff before I even consider it for any sort of repair work. Any job worth doing is worth doing right. If you're trying to attach surface-mount components, invest in the proper soldering/desoldering equipment instead of looking for impractical shortcuts. It may cost more at the get-go, but it'll cost a lot less in the long run. Keep the peace(es). -- Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute. (Known to some as Bruce Lane, ARS KC7GR, kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com "If Salvador Dali had owned a computer, would it have been equipped with surreal ports?" Article: 94506 of rec.radio.amateur.homebrew From: Robert Baer Subject: Re: epoxy instead of solder? References: Message-ID: Date: Thu, 06 Oct 2005 08:44:32 GMT John Fields wrote: > 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. > I do not know about Masterbonds conductive epoxy(ies), but i have used silver conductive epoxy. 1) EXPENSIVE, 2) good for short-term and medium-term repair, but no where as reliable as a solder connection. Article: 94507 of rec.radio.amateur.homebrew From: Robert Baer Subject: Re: epoxy instead of solder? References: Message-ID: Date: Thu, 06 Oct 2005 08:46:31 GMT Dr. Anton T. Squeegee wrote: > In article , TRABEM <> > says... > > >>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:>: > > > Not really. Consider the angle of serviceability. It's easy enough > to use a 'HoTweezer' station to replace a bad chip component secured > with solder. It's darn near impossible to replace the same component if > secured with Epoxy. > > Also, I'm not convinced that "conductive" Epoxy really is. I'd > want to see some real numbers on resistance per cm/squared on the stuff > before I even consider it for any sort of repair work. > > Any job worth doing is worth doing right. If you're trying to > attach surface-mount components, invest in the proper > soldering/desoldering equipment instead of looking for impractical > shortcuts. It may cost more at the get-go, but it'll cost a lot less in > the long run. > > Keep the peace(es). > > The silver conductive epoxy is extremely conductive, and even tho i never measuresd the resistivity, i would wager that it is better than copper if used properly. Article: 94508 of rec.radio.amateur.homebrew From: "Ron H" References: Subject: Re: epoxy instead of solder? TRY ADHESIVE Date: Thu, 6 Oct 2005 19:35:36 -0500 Message-ID: <4345bdb6_16@Output.100ProofNews.com> The 3M conductive adhesives like the 9703 work well. Not sure how they do it but it conducts in the Z axis ( thru the adhesive ) but not accross the surface direction ( X & Y axis ). It's a pressure sensitive transfer adhesive ( tape that you stick on then peel off the paper carrier leaving the adhesive behind) X-Y axis Insulation Resistance = 3.4 x 10 to the 14th Ohms/square Z axis Contact Resistance = 1.25 milliOhm-in2 Pretty neat stuff! Ron H. x-- 100 Proof News - http://www.100ProofNews.com x-- 30+ Days Binary Retention with High Completion x-- Access to over 1.9 Terabytes per Day - $8.95/Month x-- UNLIMITED DOWNLOAD Article: 94509 of rec.radio.amateur.homebrew From: Jim Thompson Subject: Re: epoxy instead of solder? TRY ADHESIVE Message-ID: References: <4345bdb6_16@Output.100ProofNews.com> Date: Thu, 06 Oct 2005 19:28:54 -0700 On Thu, 6 Oct 2005 19:35:36 -0500, "Ron H" wrote: >The 3M conductive adhesives like the 9703 work well. Not sure how they do it >but it conducts in the Z axis ( thru the adhesive ) but not accross the >surface direction ( X & Y axis ). It's a pressure sensitive transfer >adhesive ( tape that you stick on then peel off the paper carrier leaving >the adhesive behind) > >X-Y axis Insulation Resistance = 3.4 x 10 to the 14th Ohms/square >Z axis Contact Resistance = 1.25 milliOhm-in2 > >Pretty neat stuff! > >Ron H. > Sounds VERY interesting! I have some clients that need to mount components that can't stand the heat of soldering. The only problem might be "tenacity"... how much "shake, rattle and roll" can it take? ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. Article: 94510 of rec.radio.amateur.homebrew From: John Woodgate Subject: Re: epoxy instead of solder? Date: Fri, 7 Oct 2005 09:14:09 +0100 Message-ID: <5RNEDhHR5iRDFw41@jmwa.demon.co.uk> References: I read in sci.electronics.design that jpopelish@rica.net wrote (in <1128646392.685462.152870@g47g2000cwa.googlegroups.com>) about 'epoxy instead of solder?', on Thu, 6 Oct 2005: > >Robert Baer wrote: > >> The silver conductive epoxy is extremely conductive, and even tho i >> never measuresd the resistivity, i would wager that it is better than >> copper if used properly. > >Just another point of reference. From: >http://www.efunda.com/materials/solders/tin_lead.cfm >Eutectic tin lead solder has a conductivity of about 1.44*10^-5 ohm cm, >or 8.5 times that of copper. > resistivity, not conductivity. -- Regards, John Woodgate, OOO - Own Opinions Only. If everything has been designed, a god designed evolution by natural selection. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk Article: 94511 of rec.radio.amateur.homebrew From: "Jeff B" References: <4345bdb6_16@Output.100ProofNews.com> Subject: Re: epoxy instead of solder? TRY ADHESIVE Date: Fri, 7 Oct 2005 07:11:41 -0500 Message-ID: <434660db$1_9@Output.100ProofNews.com> Just go to 3m.com and search for "conductive adhesive" or "9703" "Jim Thompson" wrote in message news:o7nbk1pnnqu85udf6bgd3vtjs1aruo5b80@4ax.com... > On Thu, 6 Oct 2005 19:35:36 -0500, "Ron H" wrote: > > >The 3M conductive adhesives like the 9703 work well. Not sure how they do it > >but it conducts in the Z axis ( thru the adhesive ) but not accross the > >surface direction ( X & Y axis ). It's a pressure sensitive transfer > >adhesive ( tape that you stick on then peel off the paper carrier leaving > >the adhesive behind) > > > >X-Y axis Insulation Resistance = 3.4 x 10 to the 14th Ohms/square > >Z axis Contact Resistance = 1.25 milliOhm-in2 > > > >Pretty neat stuff! > > > >Ron H. > > > > Sounds VERY interesting! I have some clients that need to mount > components that can't stand the heat of soldering. The only problem > might be "tenacity"... how much "shake, rattle and roll" can it take? > > ...Jim Thompson > -- > | James E.Thompson, P.E. | mens | > | Analog Innovations, Inc. | et | > | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | > | Phoenix, Arizona Voice:(480)460-2350 | | > | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | > | http://www.analog-innovations.com | 1962 | > > I love to cook with wine. Sometimes I even put it in the food. x-- 100 Proof News - http://www.100ProofNews.com x-- 30+ Days Binary Retention with High Completion x-- Access to over 1.9 Terabytes per Day - $8.95/Month x-- UNLIMITED DOWNLOAD Article: 94512 of rec.radio.amateur.homebrew From: Glen Walpert Subject: Re: epoxy instead of solder? TRY ADHESIVE Message-ID: References: <4345bdb6_16@Output.100ProofNews.com> Date: Fri, 07 Oct 2005 13:29:23 GMT On Thu, 06 Oct 2005 19:28:54 -0700, Jim Thompson wrote: >On Thu, 6 Oct 2005 19:35:36 -0500, "Ron H" wrote: > >>The 3M conductive adhesives like the 9703 work well. Not sure how they do it >>but it conducts in the Z axis ( thru the adhesive ) but not accross the >>surface direction ( X & Y axis ). It's a pressure sensitive transfer >>adhesive ( tape that you stick on then peel off the paper carrier leaving >>the adhesive behind) >> >>X-Y axis Insulation Resistance = 3.4 x 10 to the 14th Ohms/square >>Z axis Contact Resistance = 1.25 milliOhm-in2 >> >>Pretty neat stuff! >> >>Ron H. >> > >Sounds VERY interesting! I have some clients that need to mount >components that can't stand the heat of soldering. The only problem >might be "tenacity"... how much "shake, rattle and roll" can it take? > > ...Jim Thompson Conductive adhesives have been discussed in Advanced Packaging magazine (IIRC, might have been another trade mag) and the main problems preventing widespread replacement of solder are not adhesion but high initial resistance (not suitable for the current required by large processors etc), and worse, gradual increase in resistance over time especially at higher temperatures and humidities due to slow oxidation of the conductors as water vapor and oxygen diffuse through the adhesive polymers. Not ready for prime time now, and might not be for a long time due to the lack of candidate impermeable adhesive polymers. Suitable now for low power apps in benign envireonments where long life is not important.