Article: 97188 of rec.radio.amateur.homebrew From: jakdedert Subject: Re: The Perfect Gift: A Tool Box References: <1145437283.988686.185570@u72g2000cwu.googlegroups.com> <7oydnSnWw5V9k9vZRVnysw@pipex.net> Message-ID: <%Dq1g.3987$MM6.1570@bignews3.bellsouth.net> Date: Wed, 19 Apr 2006 08:09:50 -0500 Highland Ham wrote: > dick on the langwang wrote: >> I've kept a long, slim, scalpel (+ pack of spare blades) in my toolbox >> for over 40yrs, wouldn't be without them. Can be used for cutting, >> poking, as an improvised instrument probe and (if push comes to shove) >> the final solution to that b****r of a problem ........ provided you >> fit a new blade first !! > =========================== > Talking tools , I consider different dental 'poking'utensils and > twizzers essential for dealing with circuit boards ,especially in the > homebrewing arena. I use these frequently. > > Frank GM0CSZ / KN6WH > > ...and on medical instruments: a pair or two (or three) of locking medical forceps are indispensable...rubber gloves are handy...syringes are good for dispensing various compounds, especially glue. Article: 97189 of rec.radio.amateur.homebrew Message-ID: <4446420E.649F2165@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: Date: Wed, 19 Apr 2006 13:59:35 GMT dick on the langwang wrote: > > I've kept a long, slim, scalpel (+ pack of spare blades) in my toolbox > for over 40yrs, wouldn't be without them. Can be used for cutting, > poking, as an improvised instrument probe and (if push comes to shove) > the final solution to that b****r of a problem ........ provided you > fit a new blade first !! You can buy an Exacto knife a lot easier, and there are a lot of different blades available. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97190 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Buildig block IF amplifiers? Message-ID: References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> <4445212A.7878413@earthlink.net> Date: Wed, 19 Apr 2006 16:47:13 GMT On Tue, 18 Apr 2006 17:26:43 GMT, "Michael A. Terrell" wrote: >Tim Shoppa wrote: >> >> clifto wrote: >> > Has anyone played with any of the new high-bandwidth op amps in IF >> > amplifier circuits? I've got an idea I want to experiment with, and >> > not a whole lot of analog design ability (though I do better with >> > building blocks than with compensating discretes), and now that >> > GBw products are cheap above 1 MHz it might look practical to >> > pursue. I have no standards for comparison since I know nothing >> > about parameters like noise figures and the like in standard >> > discrete circuits. >> >> GBw products above 1MHz have been around for a long time in op amps, if >> you don't mind dropping the bucks then you can even get GHz numbers. >> There's very little stopping anyone from using even the old >> high-bandwidth op amps in IF's. But there's not much need to. >> >> In IF strips for FM receivers, most op-amps do really bad things when >> they hit their limiting amplitudes. Google for "phase reversal" with >> "op amp". >> >> "Straight" op-amps are not easily amenable to AGC action, but I've done >> some playing around with for example LED/CdS optocouplers as very >> linear controllable-loss blocks for AGC action and they work fine up >> through the low MHz. Above a few MHz I think capacitance across the CdS >> photocell gives too much leakage in typical receiver use, although if >> you only want a limited amount of AGC I think you're good to go. >> >> It is MOST interesting to use chips like AD603's in IF's if you want >> AGC action. Many many app notes and construction articles on the web >> will show you examples of use. >> >> Are you perhaps really talking about RC active filters to replace >> crystal or mechanical IF filters? I have always been VERY PESSIMISTIC >> about this, usually even few percent tolerance capacitors (not cheap) >> cause your passband/ultimate rejection to be way way worse than what >> you expect. Different filter topologies have different tradeoffs, but >> RC active filters when you want the Q to be >100 and want even mediocre >> ultimate rejection are economically unfeasible in every analysis I've >> done. >> >> Tim. > > > >The engineers at my last job liked the Mini Circuits ERA and similar >monolithic amps. They also liked to do most of the AGC on the front end >rather than at the IF. This sometimes included an electronic attenuator >to drop the gain by 20 dB to prevent overloading a critical stage. The >customers liked the way they worked, they ordered plenty of them at >$20,000 USD each. I tried that once using MAR-6s and -11s for gain and 1n4007s as pseudo PIN diodes (Pi antenuators) between stages. Produced an excellent IF for gain, noise and intercepts but it drew near 350ma at 9V for the IF and AGC. Definately not for the qrp/battery user. Allison Article: 97191 of rec.radio.amateur.homebrew Message-ID: <44467661.263FFE21@earthlink.net> From: "Michael A. Terrell" Subject: Re: Buildig block IF amplifiers? References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> <4445212A.7878413@earthlink.net> Date: Wed, 19 Apr 2006 17:42:35 GMT Allisonnospam@nouce.bellatlantic.net wrote: > > On Tue, 18 Apr 2006 17:26:43 GMT, "Michael A. Terrell" > wrote: > > >Tim Shoppa wrote: > >> > >> clifto wrote: > >> > Has anyone played with any of the new high-bandwidth op amps in IF > >> > amplifier circuits? I've got an idea I want to experiment with, and > >> > not a whole lot of analog design ability (though I do better with > >> > building blocks than with compensating discretes), and now that > >> > GBw products are cheap above 1 MHz it might look practical to > >> > pursue. I have no standards for comparison since I know nothing > >> > about parameters like noise figures and the like in standard > >> > discrete circuits. > >> > >> GBw products above 1MHz have been around for a long time in op amps, if > >> you don't mind dropping the bucks then you can even get GHz numbers. > >> There's very little stopping anyone from using even the old > >> high-bandwidth op amps in IF's. But there's not much need to. > >> > >> In IF strips for FM receivers, most op-amps do really bad things when > >> they hit their limiting amplitudes. Google for "phase reversal" with > >> "op amp". > >> > >> "Straight" op-amps are not easily amenable to AGC action, but I've done > >> some playing around with for example LED/CdS optocouplers as very > >> linear controllable-loss blocks for AGC action and they work fine up > >> through the low MHz. Above a few MHz I think capacitance across the CdS > >> photocell gives too much leakage in typical receiver use, although if > >> you only want a limited amount of AGC I think you're good to go. > >> > >> It is MOST interesting to use chips like AD603's in IF's if you want > >> AGC action. Many many app notes and construction articles on the web > >> will show you examples of use. > >> > >> Are you perhaps really talking about RC active filters to replace > >> crystal or mechanical IF filters? I have always been VERY PESSIMISTIC > >> about this, usually even few percent tolerance capacitors (not cheap) > >> cause your passband/ultimate rejection to be way way worse than what > >> you expect. Different filter topologies have different tradeoffs, but > >> RC active filters when you want the Q to be >100 and want even mediocre > >> ultimate rejection are economically unfeasible in every analysis I've > >> done. > >> > >> Tim. > > > > > > > >The engineers at my last job liked the Mini Circuits ERA and similar > >monolithic amps. They also liked to do most of the AGC on the front end > >rather than at the IF. This sometimes included an electronic attenuator > >to drop the gain by 20 dB to prevent overloading a critical stage. The > >customers liked the way they worked, they ordered plenty of them at > >$20,000 USD each. > > I tried that once using MAR-6s and -11s for gain and 1n4007s as > pseudo PIN diodes (Pi antenuators) between stages. Produced an > excellent IF for gain, noise and intercepts but it drew near 350ma > at 9V for the IF and AGC. Definately not for the qrp/battery user. > > Allison We weren't in the QRP business. We were building hi rel equipment to track space probes. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97192 of rec.radio.amateur.homebrew From: microwaves@blueyonder.co.uk (Peter) Subject: Re: If you've nothing better to do just now ! Message-ID: <4446a592.537203447@news.blueyonder.co.uk> References: <87pc42daqbjedmqtsot3sb0q2d1ke3rtfk@4ax.com> Date: Wed, 19 Apr 2006 21:04:24 GMT On Wed, 19 Apr 2006 17:34:36 +0100, Joe McElvenney wrote: >Hi, > > If your recent copies of QST are in order of month on the >shelf, have you noticed that the letters "QST" on their spines >trace out a crude sine wave? This seems to have happened with the >January 2003 issue when they appeared to have changed the >justification of the year/month group from left to centre. > > > So there ya go - Joe, G3LLV Get out that soldering iron! You know it makes sense ... Peter G3PHO :-) Article: 97193 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: Buildig block IF amplifiers? Message-ID: References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> <4445212A.7878413@earthlink.net> <44467661.263FFE21@earthlink.net> Date: Wed, 19 Apr 2006 22:13:27 GMT On Wed, 19 Apr 2006 17:42:35 GMT, "Michael A. Terrell" wrote: >> >The engineers at my last job liked the Mini Circuits ERA and similar >> >monolithic amps. They also liked to do most of the AGC on the front end >> >rather than at the IF. This sometimes included an electronic attenuator >> >to drop the gain by 20 dB to prevent overloading a critical stage. The >> >customers liked the way they worked, they ordered plenty of them at >> >$20,000 USD each. >> >> I tried that once using MAR-6s and -11s for gain and 1n4007s as >> pseudo PIN diodes (Pi antenuators) between stages. Produced an >> excellent IF for gain, noise and intercepts but it drew near 350ma >> at 9V for the IF and AGC. Definately not for the qrp/battery user. >> >> Allison > > > We weren't in the QRP business. We were building hi rel equipment to >track space probes. Well that much was obvious. However, despite the higher power needs it's performance is stellar. I can see no reason why it would not be very high rel. The reciever it was used in has a overload threshold and dynamic range far higher than anything in the ham market. Also the NF is low giving it an excellent MDS. It was built to work weak signals effectively without overload because I have a "kilowatt charlie" less than 300yds away on the same band. Nominal RF comming down the coax from him is 25-150mw! The whole reciever pulls a whopping 2A (no signal) becuase of all of the high standing currents in RF and IF processing never mind the required 17DBM LO.. At the other end of the power spectra I've used cascode J310 FETs to build very good IFs with far lower power needs but still good AGC and gain. What's hard is building filters with at least 140db of stopband attenuation. There nothing like shielding, lots of it. Then testing, testing, testing. Allison Article: 97194 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: If you've nothing better to do just now ! Message-ID: References: <87pc42daqbjedmqtsot3sb0q2d1ke3rtfk@4ax.com> Date: Wed, 19 Apr 2006 22:15:09 GMT On Wed, 19 Apr 2006 17:34:36 +0100, Joe McElvenney wrote: >Hi, > > If your recent copies of QST are in order of month on the >shelf, have you noticed that the letters "QST" on their spines >trace out a crude sine wave? This seems to have happened with the >January 2003 issue when they appeared to have changed the >justification of the year/month group from left to centre. > > > So there ya go - Joe, G3LLV Wow there, Way to much free time. You have not been building enough! ;) Allison Article: 97195 of rec.radio.amateur.homebrew Message-ID: <4446C52A.9030008@nettally.com> From: **THE-RFI-EMI-GUY** Subject: Re: Finding short duration interference? References: <1249ghuscr3fneb@corp.supernews.com> Date: Wed, 19 Apr 2006 23:15:19 GMT This is a multi-part message in MIME format. --------------070101030504050208000304 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Check this link and see if you have same problem.... www.qsl.net/va3bmc/inter477.pdf mike wrote: > What's a good method for finding short duration interference? > > My 440 repeater is plagued by an interfering signal that lasts a small > fraction of a second, just long enough to bring up the repeater, > and repeats randomly every 20 seconds or so. > Comes and goes...Seems to be dependent on outside temperature. > Sometimes sounds like there's hum on the signal. > First thought was that it was one of those oscillating Winegard > RV TV antennas, but it doesn't seem to drift around like they > typically do. > > I hooked the repeater antenna up to the spectrum analyzer, > but the duration is too short to get thru the filters at > the bandwidth required to get any sensitivity. > > I can hear it on the mobile. > I've driven around the neighborhood, but the duration is so short > that I've not been able to track it down. Strength seems to peak > at different places blocks apart...but it's hard to tell. > > I have some experience with a double duckey and started designing > a doppler system, but it occurs that the short duration signal > will be completely washed out by the Switched Cap Filter. Don't see > how I'm gonna get the low rep-rate signal past the noise. Filter > types that I know about ain't gonna work. > > Ideas? > Thanks, mike -- Joe Leikhim K4SAT "The RFI-EMI-GUY"© "Treason doth never prosper: what's the reason? For if it prosper, none dare call it treason." "Follow The Money" ;-P --------------070101030504050208000304 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Check this link and see if you have same problem....

www.qsl.net/va3bmc/inter477.pdf

mike wrote:
What's a good method for finding short duration interference?

My 440 repeater is plagued by an interfering signal that lasts a small fraction of a second, just long enough to bring up the repeater,
and repeats randomly every 20 seconds or so.
Comes and goes...Seems to be dependent on outside temperature.
Sometimes sounds like there's hum on the signal.
First thought was that it was one of those oscillating Winegard
RV TV antennas, but it doesn't seem to drift around like they
typically do.

I hooked the repeater antenna up to the spectrum analyzer,
but the duration is too short to get thru the filters at
the bandwidth required to get any sensitivity.

I can hear it on the mobile.
I've driven around the neighborhood, but the duration is so short
that I've not been able to track it down.  Strength seems to peak
at different places blocks apart...but it's hard to tell.

I have some experience with a double duckey and started designing
a doppler system, but it occurs that the short duration signal
will be completely washed out by the Switched Cap Filter.  Don't see
how I'm gonna get the low rep-rate signal past the noise.  Filter
types that I know about ain't gonna work.

Ideas?
Thanks, mike 

-- 
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P
--------------070101030504050208000304-- Article: 97196 of rec.radio.amateur.homebrew Message-ID: <4446DD4E.36F27124@earthlink.net> From: "Michael A. Terrell" Subject: Re: Buildig block IF amplifiers? References: <1145371508.131596.99210@i40g2000cwc.googlegroups.com> <4445212A.7878413@earthlink.net> <44467661.263FFE21@earthlink.net> Date: Thu, 20 Apr 2006 01:01:48 GMT Allisonnospam@nouce.bellatlantic.net wrote: > > On Wed, 19 Apr 2006 17:42:35 GMT, "Michael A. Terrell" > wrote: > > >> >The engineers at my last job liked the Mini Circuits ERA and similar > >> >monolithic amps. They also liked to do most of the AGC on the front end > >> >rather than at the IF. This sometimes included an electronic attenuator > >> >to drop the gain by 20 dB to prevent overloading a critical stage. The > >> >customers liked the way they worked, they ordered plenty of them at > >> >$20,000 USD each. > >> > >> I tried that once using MAR-6s and -11s for gain and 1n4007s as > >> pseudo PIN diodes (Pi antenuators) between stages. Produced an > >> excellent IF for gain, noise and intercepts but it drew near 350ma > >> at 9V for the IF and AGC. Definately not for the qrp/battery user. > >> > >> Allison > > > > > > We weren't in the QRP business. We were building hi rel equipment to > >track space probes. > > Well that much was obvious. However, despite the higher power needs > it's performance is stellar. I can see no reason why it would not be > very high rel. > > The reciever it was used in has a overload threshold and dynamic > range far higher than anything in the ham market. Also the NF is low > giving it an excellent MDS. It was built to work weak signals > effectively without overload because I have a "kilowatt charlie" less > than 300yds away on the same band. Nominal RF comming down > the coax from him is 25-150mw! The whole reciever pulls a whopping > 2A (no signal) becuase of all of the high standing currents in RF and > IF processing never mind the required 17DBM LO.. > > At the other end of the power spectra I've used cascode J310 FETs > to build very good IFs with far lower power needs but still good AGC > and gain. > > What's hard is building filters with at least 140db of stopband > attenuation. There nothing like shielding, lots of it. Then testing, > testing, testing. > > Allison We built tubular filters in house, because we couldn't get what we needed, when we needed it. We built the ground station and a mobile earth station with a large mobile diesel generator for power, for the Italian government to track their launches. They had a severe overload problem, trying to set up the one station near the launch pad. Engineering was going round and round about a way to reduce the signal levels prior to the launch, that could be done quickly. My suggestion was a chain link fence near the pad to block most of the signal, till the rocket left the pad and was no longer pointing right at the ground based antennas. The receivers had lots of aluminum between stages to stop stray signals. We used a LINEAR AGC system that was a pain to get set up, but the dual diversity combiner required the linear 0 to 5 volt signals to steer the combiner. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97197 of rec.radio.amateur.homebrew Subject: Microwave Projects? From: JJ Message-ID: <4cc36$4447a312$d135c4af$31881@MDI.CA> Date: Thu, 20 Apr 2006 11:04:50 -0400 I like to build simple receivers from 1 to 2.4GHz. Any recommendations for oscillators? What schottky diode works to make a signal strength meter? Thanks JJ Article: 97198 of rec.radio.amateur.homebrew From: "John Jardine." Subject: Re: Microwave Projects? Date: Thu, 20 Apr 2006 22:26:21 +0100 Message-ID: References: <4cc36$4447a312$d135c4af$31881@MDI.CA> "JJ" wrote in message news:4cc36$4447a312$d135c4af$31881@MDI.CA... > I like to build simple receivers from 1 to 2.4GHz. > Any recommendations for oscillators? > What schottky diode works to make a signal strength meter? > > Thanks > > JJ Oscillator construction seems a big problem up there. Was trying something similar the other week. Turned out 99% art 1% science, so packed it in and now awaiting a sample of an interesting satelite downconverter chip. http://www.semiconductors.philips.com/pip/TDA8261.html , digitally covers 950 to 2175MHz using a VCO/synthesiser running at a quarter of it's mixer input frequency. VCO simply consists of a Varicap, 2 caps and a 18nH inductor. Chip is 'direct conversion'(with quadrature outputs!) and would make a wonderful 0-1GHz spectrum analyser if it's mixer ran down to a few megs. Sadly, no mention of this spec' in the datasheet, so must assume response tails off badly at the low end. john Article: 97199 of rec.radio.amateur.homebrew Message-ID: <44480E60.518DE37@earthlink.net> From: "Michael A. Terrell" Subject: Re: HB VHF low-pass filter References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> Date: Thu, 20 Apr 2006 22:43:47 GMT paul@burridge8333.fsbusiness.co.uk wrote: > > Hi gang, > > And old chum of mine suffers badly from pager interference when he's > trying to listen on the 2m band. The interference is strong to him > (S9+) and takes out all his reception, despite the fact that it's quite > a way up-band at 153Mhz. > I've been looking into designing a filter for him to cut off by 153Mhz > to better than -20db but it turns out to be rather more tricky than I'd > imagined. Even with a seven element butterworth configuration, the > difference between the 146Mhz (wanted) and the 153Mhz (unwanted is an > insignificant 6db or so. I'm just not getting enough roll-off and need > something much sharper. Worse still, the roll-off I'm seeing is on a > computer simulation of the filter with ideal components and would no > doubt be even worse with real-world Ls and Cs. Any suggestions as to > how to tackle the problem, guys? > Thanks, > P. If its just one transmitter he would be better off with a notch filter. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97200 of rec.radio.amateur.homebrew From: "Norm Mann" References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> Subject: Re: HB VHF low-pass filter Message-ID: Date: Fri, 21 Apr 2006 00:25:11 GMT wrote in message news:1145571874.839811.78600@u72g2000cwu.googlegroups.com... > Hi gang, > > And old chum of mine suffers badly from pager interference when he's > trying to listen on the 2m band. The interference is strong to him > (S9+) and takes out all his reception, despite the fact that it's quite > a way up-band at 153Mhz. > I've been looking into designing a filter for him to cut off by 153Mhz > to better than -20db but it turns out to be rather more tricky than I'd > imagined. Even with a seven element butterworth configuration, the > difference between the 146Mhz (wanted) and the 153Mhz (unwanted is an > insignificant 6db or so. I'm just not getting enough roll-off and need > something much sharper. Worse still, the roll-off I'm seeing is on a > computer simulation of the filter with ideal components and would no > doubt be even worse with real-world Ls and Cs. Any suggestions as to > how to tackle the problem, guys? > Thanks, > P. A coax stub filter to notch out the pager would probably work better. It's cheap to make, but it also has some drawbacks - signals within roughly +/- 10 MHz of the notch may have as much as 10 dB of attenuation. Your friend may be able to cope with some attenuation better than 100% overload. -NM Article: 97201 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> Subject: Re: HB VHF low-pass filter Message-ID: Date: Fri, 21 Apr 2006 00:38:04 GMT "Norm Mann" wrote in message news:HDV1g.10938$oQ2.4421@trnddc05... > > wrote in message > news:1145571874.839811.78600@u72g2000cwu.googlegroups.com... >> Hi gang, >> >> And old chum of mine suffers badly from pager interference when he's >> trying to listen on the 2m band. The interference is strong to him >> (S9+) and takes out all his reception, despite the fact that it's quite >> a way up-band at 153Mhz. >> I've been looking into designing a filter for him to cut off by 153Mhz >> to better than -20db but it turns out to be rather more tricky than I'd >> imagined. Even with a seven element butterworth configuration, the >> difference between the 146Mhz (wanted) and the 153Mhz (unwanted is an >> insignificant 6db or so. I'm just not getting enough roll-off and need >> something much sharper. Worse still, the roll-off I'm seeing is on a >> computer simulation of the filter with ideal components and would no >> doubt be even worse with real-world Ls and Cs. Any suggestions as to >> how to tackle the problem, guys? >> Thanks, >> P. > > A coax stub filter to notch out the pager would probably work better. > It's cheap to make, but it also has some drawbacks - signals within > roughly +/- 10 MHz of the notch may have as much as 10 dB of attenuation. > Your friend may be able to cope with some attenuation better than 100% > overload. > > -NM > > >You will not meet your goals with a real world LPF. A coaxial Stub may >yield -20dB attenuation but have terrible in band (2M) VSWR and high loss. The previous poster is correct- a notch- particularly an asymmetrcial notch is the proper solution. 50dB or greater attenuation at 163 MHz with in band loss of under -0.4dB is easily achieved. See: http://www.eham.net/reviews/detail/3716 Or: http://www.eham.net/reviews/detail/385 Dale W4OP Article: 97202 of rec.radio.amateur.homebrew From: dplatt@radagast.org (Dave Platt) Subject: Re: HB VHF low-pass filter Date: Fri, 21 Apr 2006 00:48:51 -0000 Message-ID: <124gavjj0lrcq6c@corp.supernews.com> References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> In article , Norm Mann wrote: >> And old chum of mine suffers badly from pager interference when he's >> trying to listen on the 2m band. The interference is strong to him >> (S9+) and takes out all his reception, despite the fact that it's quite >> a way up-band at 153Mhz. >A coax stub filter to notch out the pager would probably work better. It's >cheap to make, but it also has some drawbacks - signals within roughly +/- >10 MHz of the notch may have as much as 10 dB of attenuation. Your friend >may be able to cope with some attenuation better than 100% overload. PAR Electronics makes some two- and three-section anti-pager notch filters which are quite effective. From their looks and construction I infer that they use helical resonators. Might be possible to homebrew something similar? -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! Article: 97203 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: HB VHF low-pass filter Message-ID: References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> Date: Fri, 21 Apr 2006 01:46:57 GMT On 20 Apr 2006 15:24:34 -0700, paul@burridge8333.fsbusiness.co.uk wrote: >Hi gang, > >And old chum of mine suffers badly from pager interference when he's >trying to listen on the 2m band. The interference is strong to him >(S9+) and takes out all his reception, despite the fact that it's quite >a way up-band at 153Mhz. >I've been looking into designing a filter for him to cut off by 153Mhz >to better than -20db but it turns out to be rather more tricky than I'd >imagined. Even with a seven element butterworth configuration, the >difference between the 146Mhz (wanted) and the 153Mhz (unwanted is an >insignificant 6db or so. I'm just not getting enough roll-off and need >something much sharper. Worse still, the roll-off I'm seeing is on a >computer simulation of the filter with ideal components and would no >doubt be even worse with real-world Ls and Cs. Any suggestions as to >how to tackle the problem, guys? >Thanks, >P. Hit the ARRL web site for the TIS pages and fine the stub solution that was published. It's a dual notch filter using stubs and a intermediate 1/4 wave section. They used hardline (ut141) and building it is a matter of measuring accurately and soldering. I've notched out a a local pager just using a coax T and a ~12-13" open stub section of LMR400 (1/4wl @ pager frequency). Allison Article: 97204 of rec.radio.amateur.homebrew Subject: Re: Microwave Projects? From: JJ References: <4cc36$4447a312$d135c4af$31881@MDI.CA> Message-ID: Date: Thu, 20 Apr 2006 23:39:04 -0400 Very interesting receiver chip. I see Maxim makes those too. Any other manufacturers that would interest microwave experimenters? JJ Article: 97205 of rec.radio.amateur.homebrew From: - exray - Subject: Re: HB VHF low-pass filter Date: Fri, 21 Apr 2006 08:00:54 -0400 Message-ID: <124hibtc27ove7e@corp.supernews.com> References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> Allisonnospam@nouce.bellatlantic.net wrote: > > I've notched out a a local pager just using a coax T and a ~12-13" > open stub section of LMR400 (1/4wl @ pager frequency). > > > Allison I'd try that first. I work in cable tv and one of our older methods of "scrambling" was to use an interfering carrier ~2 MHz above the video. It was fairly easy to use a little stub of coax and completely remove the jamming...ie >40db of rejection with only a few db hit on the video carrier 2 MHz away. In your case 7 MHz away it (insertion loss) will be a non-issue. You'll find the stub length to be critical to about 5mm so its a true cut-n-try technique. Use some old scrap television cable for the stub so you don't waste the good stuff. GL, Bill Article: 97206 of rec.radio.amateur.homebrew From: - exray - Subject: Re: HB VHF low-pass filter Date: Fri, 21 Apr 2006 15:38:37 -0400 Message-ID: <124id63sknn9l49@corp.supernews.com> References: <1145571874.839811.78600@u72g2000cwu.googlegroups.com> <124hibtc27ove7e@corp.supernews.com> <1145644529.770915.286060@u72g2000cwu.googlegroups.com> K7ITM wrote: > I question the bit about insertion loss 7MHz away being a non-issue > with only a single open stub across the line. If you put an open stub > of lossless 50 ohm line a quarter-wave long at 153MHz across the feed > line, it puts a short across the line at 153, but it puts 0.26-j3.58 > ohms across it at 146MHz. That's a 99% reflection, or SWR close to > 200:1 at 146. It's only about a 17dB loss, but that's more loss than > I'd want. You're correct. Someone pointed this out to me via email so I'll retract my recommendation of using the stub. Thanks, Bill Article: 97207 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Favorite low power receiver ICs? Date: Fri, 21 Apr 2006 13:28:10 -0700 Message-ID: <124ig4j152ptd07@corp.supernews.com> Anyone have a favorite low power (as in tens of milliwatts) receiver IC that you can still get ahold of? I'm looking to see what could potentially replace some Philips UAA2080's, which are no longer available new from Philips. They were a really great part, giving you an oscillator, frequency mulitplier, RF pre-amp, I/Q mixers and a bit of demodulation (they were intended for use in pagers but gave you the raw I/Q output so could be pushed into service for other applications too) -- all of this for less than 10mW! Looking around at parts, it seems that even plain old mixers now often run 50mW or more. Ostensibly this seems due to their usage at higher frequencies (low GHz range), which I can understand, but it's a feature don't require. I'm after low power parts for dealing with more pedestrian frequencies (low to mid-hundreds of MHz) and small bandwidths (single digit kHz). Thanks, ---Joel KOlstad Article: 97208 of rec.radio.amateur.homebrew From: Roberto IZ5FCY Subject: FA Kenwood Station Monitor Date: Fri, 21 Apr 2006 22:59:52 +0200 Message-ID: Hi, a splendid Kenwood Station Monitor SM-230: http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=9714764236&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1 -- 73's de IZ5FCY Roberto Article: 97209 of rec.radio.amateur.homebrew From: "amdx" Subject: Rec.radio.amateur antenna Date: Fri, 21 Apr 2006 18:54:50 -0500 Message-ID: <2e6dd$444970cb$45011502$11128@KNOLOGY.NET> I get no posts in rec radio amateur antenna. Is anyone else having problems? I had some problems the past couple days, but today nothing appears. Mike Article: 97210 of rec.radio.amateur.homebrew From: biascomms Subject: Re: Favorite low power receiver ICs? References: <124ig4j152ptd07@corp.supernews.com> Message-ID: Date: Sat, 22 Apr 2006 00:12:41 GMT Joel Kolstad wrote: > Anyone have a favorite low power (as in tens of milliwatts) receiver IC > that > you can still get ahold of? I'm looking to see what could potentially > replace > some Philips UAA2080's, which are no longer available new from Philips. > They were a really great part, giving you an oscillator, frequency > mulitplier, RF pre-amp, I/Q mixers and a bit of demodulation (they were > intended for use in pagers but gave you the raw I/Q output so could be > pushed into service for other applications too) -- all of this for less > than 10mW! > > Looking around at parts, it seems that even plain old mixers now often run > 50mW or more. Ostensibly this seems due to their usage at higher > frequencies (low GHz range), which I can understand, but it's a feature > don't require. I'm after low power parts for dealing with more pedestrian > frequencies (low to mid-hundreds of MHz) and small bandwidths (single > digit kHz). > > Thanks, > ---Joel KOlstad Most manufacturers seem to be obsessed with "high intercept point", which is desirable in some instances, but always carries a major power penalty. With the demise of some of my favourite ICs, I'm going back to discrete components for many things. Bob -- Everything gets easier with practice, except getting up in the morning! Article: 97211 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: Rec.radio.amateur antenna Date: Fri, 21 Apr 2006 17:19:22 -0700 Message-ID: <124itkasgufm6b4@corp.supernews.com> References: <2e6dd$444970cb$45011502$11128@KNOLOGY.NET> amdx wrote: > I get no posts in rec radio amateur antenna. Is anyone else having problems? > I had some problems the past couple days, but today nothing appears. > Mike It's alive and well -- there have been numerous postings every day. Roy Lewallen, W7EL Article: 97212 of rec.radio.amateur.homebrew From: - exray - Subject: Re: Rec.radio.amateur antenna Date: Fri, 21 Apr 2006 20:21:45 -0400 Message-ID: <124itovrrtof703@corp.supernews.com> References: <2e6dd$444970cb$45011502$11128@KNOLOGY.NET> amdx wrote: > I get no posts in rec radio amateur antenna. Is anyone else having problems? > I had some problems the past couple days, but today nothing appears. > Mike > > No problem here. -Bill Article: 97213 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA:1DAY+,VIRBOPLEX'PRESENTATION'+ MO Message-ID: Date: Sat, 22 Apr 2006 00:56:49 GMT Presentation in very fine possibly NOS condition in original box with documents + other stuff too: see at: http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy Tnx for looking, more coming, heytubeguy Article: 97214 of rec.radio.amateur.homebrew From: "John Jardine." Subject: Re: Microwave Projects? Date: Sat, 22 Apr 2006 15:16:46 +0100 Message-ID: References: <4cc36$4447a312$d135c4af$31881@MDI.CA> "JJ" wrote in message news:baf7d$444853d8$d135c4af$15108@MDI.CA... > Very interesting receiver chip. I see Maxim makes those too. > Any other manufacturers that would interest microwave experimenters? > > JJ Also hoping the RF guys could throw in a couple of tasty pointers. Seems plenty of amps and mixers out there but if it's not cellphone stuff then seemingly very little else. john Article: 97215 of rec.radio.amateur.homebrew From: "amdx" Subject: low distortion antenna amp Date: Sat, 22 Apr 2006 12:55:44 -0500 Message-ID: Hi All, The article below shows a low distortion antenna amp for BCB and SW. http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%2 0Amplifiers.pdf Note the wrap. When built as a push pull it has stated specs such as 12db power gain ICP2in +100 ICP3in +35 Flat from 100khz to 30 Mhz I'm interested in comments, and I'm also trying to generate some interest in maybe some simulations to work on biasing options. The author states more work needs to be done on transformer winding ratios. Take a look, it is an interesting article. Mike Article: 97216 of rec.radio.amateur.homebrew From: "Morey" References: <1144681555.714402.227210@u72g2000cwu.googlegroups.com> Subject: Re: Interested? Become a Healthy Adult Male, ("Ham", M9ZZZ) and not a Coughing Bird ("CB", H5N1) - here's the FAQ for you! Date: Sat, 22 Apr 2006 16:23:08 -0500 Message-ID: <26f26$444a91cb$d17c353a$9960@123.NET> I am in agreement withyou friend. I am KC8W0Q in Cadillac MI. U.S.A. Thanks for sticking to your guns. My name is Morey Cotton. Plod's Conscience wrote in message news:1144681555.714402.227210@u72g2000cwu.googlegroups.com... > A necessary preface..... > > (It is becoming increasingly difficult to fly the flag for > decency and for civilised behaviour in Radio Hammery. Even > the Usenet newsgroups dedicated to the cause have degenerated > into a hotbed of abusive onslaughts by those who ought to know > better; the Nugatory Numpties who boast of an interest > exceeding 10, 20, 30, 40 or even 50 years and yet who have > proved themselves incapable of even meeting the trivial exam > standards set for 6-year-olds. However, there still exists > the fundamental basis on which Ham Radio is based, and > that will never die. This FAQ ("What Is Ham Radio?") will > be regularly published and will not be shouted or bullied > down. It is important that those of a technical bent, who > are the natural seed-corn of Radio Hammery and who > gravitate towards us to be the real novitiate, can > still find us, (and know that we are still here), their fellows.) > > -----ooooo----- > > So,.....What is Ham Radio? > > Ham Radio is a technical pursuit for those who > are interested in the science of radio wave > propagation and who are also interested in the > way that their radios function. It has a long-standing > tradition of providing a source of engineers who > are born naturals. > > Ham Radio awakens in its aficionados a whole-life > fascination with all things technical and gives > an all-abiding curiosity to improve one's scientific > knowledge. It's a great swimming pool, please dive in! > > This excitement causes a wish to share the experience > with ones fellow man, and shows itself in the > gentlemanly traditions of Ham Radio. > > Radio Hams are in a unique privileged position in that > they can construct and operate their own equipment! No-one > else has this privilege. Users, such as broadcasters, > the po lice and armed farces, CBers and mobile phone > users have to purchase ready-made gear. Manufacturers > are not licensed to operate their gear. Radio Hams > are qualified to design, build and then > operate their own pieces of equipment. They do this > with gusto, and also repair and modify their own > equipment. This is a privilege well worth the effort > to gain, and one to be jealously guarded. > > The excitement that drives a Radio Ham starts with > relatively simple technologies at first, perhaps making > his own Wimshurst machine and primary cells. Small pieces > of test equipment follow, possibly multimeters and signal > generators. Then comes receivers and transmitters. It is with > the latter that communication with like-minded technically > motivated people takes off. The scope for technical > development grows with the years > and now encompasses DSP and DDS. There is also a great deal > of excitement in the areas of computer programming to > be learnt and applied. > > The technical excitement motivates Radio Hams to compete > with each other to determine who has designed and manufactured > the best-quality station. This competitiveness is found in DXing, > competitions and fox-hunts. > > -----OOOOO---- > > However, beware! A Ham Radio licence is such a > desirable thing to have that there are large > numbers of people who wish to be thought of > as Radio Hams when, in fact, they are nothing > of the kind! Usually such people are a > variation of the CB Radio hobbyist; they buy their > radios off the shelf and send them back to be > repaired; they are not interested in technical discussion > and sneer at those who are; they have no idea how > their radios work inside and have no wish to find out; > they are free with rather silly personal insults. > > These CB types engage in the competitive activities > with their Cheque-Book-purchased off-the-shelf radios > in a forlorn effort to prove that they are Radio Hams. > > No _REAL_ Radio Hams are deceived by such people! > > -----ooooo----- > > One infallible way to disambiguate the CB Radio Hobbyist > from the _REAL_ Radio Ham is to solicit their view of the > difference between CB Radio and Ham Radio. A Radio Ham will > perceive Ham Radio to be a technical pursuit and will > perceive CB Radio to be a social communications facility > no different in essence to a land-line telephone or a > GSM mobile in the hands of a 6-year-old. Thus a Radio Ham > could also hold a CB licence safe in the knowledge that > such a licence says no more about him than having a land-line > telephone, whilst continuing to regard Ham Radio as a separate > technical pursuit. > > A CB Radio hobbyist, on the other hand, sees no difference between > a Ham Radio licence and a CB Radio licence. To him, they are > sisters-under-the-skin. Wrongly, the CB Radio Hobbyist then > tries to classify himself as the equal of the Radio > Ham when, in fact, he is nothing of the kind. > > Ham Radio is not CB Radio and has no common ground with it! > Ham Radio is _THE_ technical pursuit for gentlemen; CB Radio > is the operating hobby for those who buy their rigs and > equipment off the shelf. > > -----ooooo----- > > If you are the sort of person who is motivated by > a technical interest in how things work; if you took apart > malfunctioning clocks, toasters and the like and put them > right despite never having seen them working, then > a Ham Radio licence is your traditional route! There has > never been a shortage of such people, and those who gravitate > towards such an interest have always been welcomed into > our shacks and their interests fostered. There is not today, > nor has there ever been, a need to go out and encourage > and press children, children who have never expressed an > interest in Ham Radio, to come into our shacks. Such an > activity should cause eyebrows to be raised - what > normal well-adjusted adults seek the social acquaintance > of children?! > > -----ooooo----- > > Please remember that this FAQ is a _POSITIVE EXHORTATION_ > to you to exert yourselves to join our fraternity! (If you find > otherwise, then perhaps you are already classing yourself in the > mediocre groups of those who are criticised in the FAQ and from > whom we _MUST_ dissociate? If so - it's never too late for > a re-taxonomisation on your part - there's nothing elitist about > us, and we welcome all those who are prepared to put themselves > out in order to join our ranks!) > From "know code" Sun Apr 23 01:28:42 EDT 2006 Article: 97217 of rec.radio.amateur.homebrew Date: Sat, 22 Apr 2006 22:52:10 +0200 From: know code Reply-To: "know code" User-Agent: Thunderbird 1.5.0.2 (Windows/20060308) MIME-Version: 1.0 Newsgroups: uk.radio.amateur,rec.radio.amateur.policy,rec.radio.amateur.homebrew Subject: Re: Interested? Become a Healthy Adult Male, ("Ham", M9ZZZ) and not a Coughing Bird ("CB", H5N1) - here's the FAQ for you! References: <1144681555.714402.227210@u72g2000cwu.googlegroups.com> <26f26$444a91cb$d17c353a$9960@123.NET> In-Reply-To: <26f26$444a91cb$d17c353a$9960@123.NET> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Lines: 13 Message-ID: <444a977a$0$31266$dbd41001@news.wanadoo.nl> Organization: Wanadoo NNTP-Posting-Date: 22 Apr 2006 20:52:10 GMT NNTP-Posting-Host: s5591cd23.adsl.wanadoo.nl X-Trace: 1145739130 dr3.euro.net 31266 85.145.205.35:3912 X-Complaints-To: abuse@wanadoo.nl Path: news.unc.edu!canoe.uoregon.edu!hammer.uoregon.edu!news.glorb.com!feeder.enertel.nl!nntpfeed-01.ops.asmr-01.energis-idc.net!news2.euro.net!postnews2.euro.net!news.wanadoo.nl!not-for-mail Xref: news0.isis.unc.edu uk.radio.amateur:271109 rec.radio.amateur.policy:258380 rec.radio.amateur.homebrew:97217 Morey wrote: > I am in agreement withyou friend. I am KC8W0Q in Cadillac MI. U.S.A. > Thanks for sticking to your guns. My name is Morey Cotton. > Plod's Conscience wrote in message > news:1144681555.714402.227210@u72g2000cwu.googlegroups.com... >> A necessary preface..... >> >> (It is becoming increasingly difficult to fly the flag for >> decency and for civilised behaviour in Radio Hammery. Loads of drivel snipped..... OMG, Beanie has got a top-poster fan club..... Article: 97218 of rec.radio.amateur.homebrew From: "The Magnum" References: <1144681555.714402.227210@u72g2000cwu.googlegroups.com> <26f26$444a91cb$d17c353a$9960@123.NET> <444a977a$0$31266$dbd41001@news.wanadoo.nl> Subject: Re: Interested? Become a Healthy Adult Male, ("Ham", M9ZZZ) and not a Coughing Bird ("CB", H5N1) - here's the FAQ for you! Date: Sat, 22 Apr 2006 23:06:22 +0100 Message-ID: <444ab74f$0$20107$834e42db@reader.greatnowhere.com> "know code" wrote in message news:444a977a$0$31266$dbd41001@news.wanadoo.nl... > Morey wrote: > > I am in agreement withyou friend. I am KC8W0Q in Cadillac MI. U.S.A. > > Thanks for sticking to your guns. My name is Morey Cotton. > > Plod's Conscience wrote in message > > news:1144681555.714402.227210@u72g2000cwu.googlegroups.com... > >> A necessary preface..... > >> > >> (It is becoming increasingly difficult to fly the flag for > >> decency and for civilised behaviour in Radio Hammery. > > Loads of drivel snipped..... > > OMG, Beanie has got a top-poster fan club..... Beanie's got a boyfriend, Beanie's got a boyfriend.....Seriously Morey a few people do agree to a degree with Beanie but it's the pathetic repetitive way he goes about it that drives everyone nuts... If he was to make a less insulting post with the same basic points then I feel he would get much further in his quest for all things "Hammery"... Graham -- -.-. -... / .-. .- -.. .. --- Radio is only a Hobby. Don't let it rule your life... 73/51 - Graham, 26-Golf Charlie-19 Article: 97219 of rec.radio.amateur.homebrew From: gwatts Subject: Re: Microwave Projects? References: <4cc36$4447a312$d135c4af$31881@MDI.CA> Message-ID: <9Fz2g.6699$kg.5945@news02.roc.ny> Date: Sun, 23 Apr 2006 00:22:47 GMT JJ wrote: ... > What schottky diode works to make a signal strength meter? Schottky diodes are soooo 20th Century, http://www.analog.com/en/prod/0%2C2877%2CAD8313%2C00.html -W8LNA Article: 97220 of rec.radio.amateur.homebrew From: "amdx" References: <1145744631.219730.126750@i40g2000cwc.googlegroups.com> Subject: Re: low distortion antenna amp Date: Sat, 22 Apr 2006 19:26:38 -0500 Message-ID: "K7ITM" wrote in message news:1145744631.219730.126750@i40g2000cwc.googlegroups.com... > Yes, it's an interesting article. I do think you need to ask yourself > exactly what problem you're trying to solve before just jumping in, > though. One thing that can be very useful is an antenna/preselector > that can get rid of "boomers" before they get to the amplifier. For > example, a small tuned loop can be oriented to null an on-frequency > interfering signal, and will have enough selectivity (assuming it's > tuned) that off-frequency boomers will be much less problem. That > doesn't work if you _must_ listen to everything all the time, though > even then notching out one or two large signals can be useful. Because > of the very high atmospheric noise on MW and even up into HF, there is > seldom a need for a very good noise figure; the distortion performance > takes precidence because of all the large signals around. The application where I saw this used, was in an antenna phasing unit, the low distortion helped reduced mixing products in the output of the phasing unit. I didn't see any noise figure in the article, but was told it was 3 or 4 db, (ten years ago). > With a good antenna, there may be no need for an amplifier before the > mixer at all, and it's possible to build mixers with input IP3s up > around +50dBm -- there are people that read this group that know how to > do that. Once past the mixer, you can filter, and if your _filter_ had > low enough distortion and selects the signal you want while attenuating > others, the rest of the amplifier chain doesn't have to be _quite_ as > good. I'm thinking of using the amp on a Flag/Pennant antenna which has a low output. > I have an abiding interest in amplifiers with good distortion > performance over just the band mentioned, though, and I can tell you > that over most of it, you can do quite well with modern op amps. One > example (but not the only one) is the circuit on the front page of the > OPA847 data sheet. The OPA847 also has very respectably low noise. > There are a few non-operational-amplifiers that do quite well, too. > The IC amps generally have more noise, I think, than what's mentioned > in the article (I haven't read it all -- yet), but they should be > adequate for at least MF and lower HF work. > > Just this morning I came across a PDF talking about using simulation > software to optimize an amplifier for good distortion performance--it > was an ap note that touted the (somewhat expensive for ham use) > simulation software from that company. I didn't bother downloading it > because it was out of both my price range (the software) and my > frequency range (the ap note). > > I'm curious about comments from BCB DXers--from what I've seen, it's > hard to find signals you could listen to that are all that small, > because there are so many stations on the air that every "channel" has > something at least moderately large in it. For example, I see local > stations here at about -30dBm on the antenna I'm using, and I can see > signals every 10kHz across the whole band that are seldom lower than > -100dBm--just one or two that are lower than that and not by much. In > that situation, a +40dBm TOI should be adequate: distortion from the > -30dBm signals would be 140dB below them, or 50dB below the smallest > signals I might want to listen to. But maybe if I spent more time > looking at other times of the day, I'd get different results...and > certainly having a neighbor running a kW on the same HF band I'm trying > to listen to would require much better performance. > I don't have the understanding of the numbers you seem to, but I heard others look for better amps because of mixing products especially on the AM band. The trick in the AM BCB is to null out those large signals to hear the smaller signals. > Cheers, > Tom > Thanks for your interest and thoughtful response, BTW the phasing circuit is at http://www.kongsfjord.no/dl/Antennas/MW%20Phaser%20no2%20III.pdf Found on the following URL with many other good articles. http://www.kongsfjord.no/dl/dl.htm Mike Article: 97221 of rec.radio.amateur.homebrew From: Bob Liesenfeld Subject: Homebrew connectors Date: Sat, 22 Apr 2006 20:07:29 -0500 Message-ID: <444AD351.AD9EA178@visi.com> Hi gang, I've been thinking about making some homebrew connectors for RG-174/U coax. I plan to use them to interconnect several enclosures made of PC board material. I envision something like an SMB connector made from some of the brass tubing that can be found in hobby shops. Rather than re-invent the wheel, I thought I would ask here if anyone has done something like this. The goal is to avoid the large size of something like a BNC connector along with the attendant high cost of most all RF connectors. Tnx! Bob WB0POQ Article: 97222 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <444AD351.AD9EA178@visi.com> Subject: Re: Homebrew connectors Message-ID: Date: Sun, 23 Apr 2006 02:18:10 GMT "Bob Liesenfeld" wrote in message news:444AD351.AD9EA178@visi.com... > Hi gang, > I've been thinking about making some homebrew connectors for RG-174/U > coax. I plan to use them to interconnect several enclosures made of PC > board material. I envision something like an SMB connector made from > some of the brass tubing that can be found in hobby shops. Rather than > re-invent the wheel, I thought I would ask here if anyone has done > something like this. The goal is to avoid the large size of something > like a BNC connector along with the attendant high cost of most all RF > connectors. > > Tnx! > > Bob WB0POQ > > Hi Bob, Why not use SMA or SMB? I used perhaps 30- 40 in my homebrew RX and it makes for easy fast connect/disconnect. The connectors are cheap as are the crimp tool. One can assemble a jumper in 3-4 minutes. I would not advise the RG-174 if you will be doing any soldering. Spend a few pennies more per foot and use RG-188/RG-316 teflon. Dale W4OP > Article: 97223 of rec.radio.amateur.homebrew From: Ed Bailen Subject: Re: Accurate voltage calibration Date: Sat, 22 Apr 2006 23:04:33 -0500 Message-ID: <0lul42d96cfh6c0rad5e4us9ochucfkjgn@4ax.com> References: <1145112749.276559.84010@u72g2000cwu.googlegroups.com> On 15 Apr 2006 07:52:29 -0700, "K7ITM" wrote: >I'd suggest you either find a calibrator to connect your meter to, or >make something you can use as a transfer standard. Maxim, for example, >has some reasonably low cost voltage references with good stability >(very few ppm/C). Then calibrate the transfer standard against some >known in-calibration volt meter or calibrator, at a known temperature, >and use it. I'd think in Scottsdale you could find a calibration >service that would do the job for you, or maybe you know someone who >has access to an accurate voltmeter. Of course, you should really do >it for several ranges. You can maybe calibrate a voltage divider >yourself, but it would save a lot of trouble if you could just do it >directly. If you don't know anyone who works with more accurate >instruements regularly and don't want to pay for a calibration, perhaps >you could pay a visit to the EE or physics department in Tempe and use >one of their instruments. > Most of the equipment I've seen at University EE departments (even grad school), hasn't seen a calibration lab in 3 or 4 decades. Some time back, a firend gave me a Leeds & Northrup Presision Potentiometer. I've used it occasionally to check some voltmeters, but I don't have anything over 3-1/2 digits of resolution. Regards, Ed > > >Cheers, >Tom Article: 97224 of rec.radio.amateur.homebrew From: "Dale Parfitt" References: <444AD351.AD9EA178@visi.com> Subject: Re: Homebrew connectors Message-ID: Date: Sun, 23 Apr 2006 05:00:11 GMT "Tim Wescott" wrote in message news:lMKdnSnrG_qoe9fZRVn-tg@web-ster.com... > Dale Parfitt wrote: > >> "Bob Liesenfeld" wrote in message >> news:444AD351.AD9EA178@visi.com... >> >>>Hi gang, >>> I've been thinking about making some homebrew connectors for RG-174/U >>>coax. I plan to use them to interconnect several enclosures made of PC >>>board material. I envision something like an SMB connector made from >>>some of the brass tubing that can be found in hobby shops. Rather than >>>re-invent the wheel, I thought I would ask here if anyone has done >>>something like this. The goal is to avoid the large size of something >>>like a BNC connector along with the attendant high cost of most all RF >>>connectors. >>> >>>Tnx! >>> >>>Bob WB0POQ >>> >>>Hi Bob, >> >> >> Why not use SMA or SMB? I used perhaps 30- 40 in my homebrew RX and it >> makes for easy fast connect/disconnect. The connectors are cheap as are >> the crimp tool. One can assemble a jumper in 3-4 minutes. I would not >> advise the RG-174 if you will be doing any soldering. Spend a few pennies >> more per foot and use RG-188/RG-316 teflon. >> >> Dale W4OP >> >> >> > Where do you get connectors? The ones I see in Digi-Key are something > like $5.00 a crack. If I'm missing something please let me know! > I got mine from The RF Connection in MD. Admittedly I bought perhaps a hundred or so. Dale W4OP Article: 97225 of rec.radio.amateur.homebrew From: Roy Lewallen Subject: Re: Homebrew connectors Date: Sat, 22 Apr 2006 23:47:58 -0700 Message-ID: <124m8ov6k3rlnd6@corp.supernews.com> References: <444AD351.AD9EA178@visi.com> See if you can find a drawing of a Peltola connector. This is a very low cost but high performance connector for RG-174 type cable (having a solid center conductor) designed by Ron Peltola at Tektronix and used in Tek scopes and other equipment for many years. You're likely to find some to look at in just about any analog Tek scope from the '70s onwards. Roy Lewallen, W7EL Bob Liesenfeld wrote: > Hi gang, > I've been thinking about making some homebrew connectors for RG-174/U > coax. I plan to use them to interconnect several enclosures made of PC > board material. I envision something like an SMB connector made from > some of the brass tubing that can be found in hobby shops. Rather than > re-invent the wheel, I thought I would ask here if anyone has done > something like this. The goal is to avoid the large size of something > like a BNC connector along with the attendant high cost of most all RF > connectors. > > Tnx! > > Bob WB0POQ > > > Article: 97226 of rec.radio.amateur.homebrew From: "amdx" References: <444AD351.AD9EA178@visi.com> Subject: Re: Homebrew connectors Date: Sun, 23 Apr 2006 06:33:54 -0500 Message-ID: <6ba60$444b661d$45011502$17492@KNOLOGY.NET> "Bob Liesenfeld" wrote in message news:444AD351.AD9EA178@visi.com... > Hi gang, > I've been thinking about making some homebrew connectors for RG-174/U > coax. I plan to use them to interconnect several enclosures made of PC > board material. I envision something like an SMB connector made from > some of the brass tubing that can be found in hobby shops. Rather than > re-invent the wheel, I thought I would ask here if anyone has done > something like this. The goal is to avoid the large size of something > like a BNC connector along with the attendant high cost of most all RF > connectors. > > Tnx! > > Bob WB0POQ > You can reduce the connector number by one half by drilling a hole in your PCB enclosure and running the >input cable inside the box and soldering it to the board, then put a connector on the other end of the cable. All outputs> would have the connector mounted to the box. Mike Article: 97227 of rec.radio.amateur.homebrew From: "Ban" References: Subject: Re: low distortion antenna amp Message-ID: <4vO2g.18443$6e2.3695@news.edisontel.com> Date: Sun, 23 Apr 2006 16:26:28 +0200 amdx wrote: > Hi All, > The article below shows a low distortion antenna amp for BCB and SW. > > http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%2 > 0Amplifiers.pdf > I know the lossless feedback based on Dr. Norton (Anzac Electronics) since 1977, when a German M. Martin DJ7VY published in CQ-DL a two stage preamp for 145/440MHz with BFT66 and BFR34A. I modified this amp for my thesis on phased array ultrasonic flaw detectors for lower frequencies. I got much better performance than with the Plessey SL531. F"=1.9dB, and phaseshift change of less than 1deg. over 102dB dynamic range until +16dBm O/P. -- ciao Ban Apricale, Italy Article: 97228 of rec.radio.amateur.homebrew From: "amdx" References: <4vO2g.18443$6e2.3695@news.edisontel.com> Subject: Re: low distortion antenna amp Date: Sun, 23 Apr 2006 15:11:36 -0500 Message-ID: <5d131$444bdf73$45011502$7338@KNOLOGY.NET> "Ban" wrote in message news:4vO2g.18443$6e2.3695@news.edisontel.com... > amdx wrote: > > Hi All, > > The article below shows a low distortion antenna amp for BCB and SW. > > > > http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%2 > > 0Amplifiers.pdf > > > > I know the lossless feedback based on Dr. Norton (Anzac Electronics) since > 1977, when a German M. Martin DJ7VY published in CQ-DL a two stage preamp > for 145/440MHz with BFT66 and BFR34A. > I modified this amp for my thesis on phased array ultrasonic flaw detectors > for lower frequencies. I got much better performance than with the Plessey > SL531. F"=1.9dB, and phaseshift change of less than 1deg. over 102dB dynamic > range until +16dBm O/P. > -- > ciao Ban > Apricale, Italy > Hi Ban, Interesting that you mention Anzac, I picked up an Anzac AM-962 at a hamfest many years ago, by the looks of it I thought it might be of the lossless feedback style, but I never found any confirmation on the net. Please help me with your terms. (1) Definition of F"----? (2) phaseshift change of less than 1deg. over 102dB dynamic range until +16dBm O/P. let me guess Very little phaseshift with a large increase of input until the output equals +16dBm?? Thanks, Mike Article: 97229 of rec.radio.amateur.homebrew From: "Ban" References: <4vO2g.18443$6e2.3695@news.edisontel.com> <5d131$444bdf73$45011502$7338@KNOLOGY.NET> Subject: Re: low distortion antenna amp Message-ID: Date: Sun, 23 Apr 2006 23:17:49 +0200 amdx wrote: > "Ban" wrote in message > news:4vO2g.18443$6e2.3695@news.edisontel.com... >> amdx wrote: >>> Hi All, >>> The article below shows a low distortion antenna amp for BCB and SW. >>> >>> > http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%2 >>> 0Amplifiers.pdf >>> >> >> I know the lossless feedback based on Dr. Norton (Anzac Electronics) >> since 1977, when a German M. Martin DJ7VY published in CQ-DL a two >> stage preamp for 145/440MHz with BFT66 and BFR34A. >> I modified this amp for my thesis on phased array ultrasonic flaw >> detectors for lower frequencies. I got much better performance than >> with the Plessey SL531. F"=1.9dB, and phaseshift change of less than >> 1deg. over 102dB dynamic range until +16dBm O/P. >> -- >> ciao Ban >> Apricale, Italy >> > Hi Ban, > Interesting that you mention Anzac, I picked up an Anzac AM-962 at a > hamfest > many years ago, by the looks of it I thought it might be of the > lossless feedback > style, but I never found any confirmation on the net. > Please help me with your terms. > > (1) Definition of F"----? > F" is the noise figure. it says how much the noise gets increased in comparison with a resistor of in this case 50 ohms. > (2) phaseshift change of less than 1deg. over 102dB dynamic > range until +16dBm O/P. > > let me guess > Very little phaseshift with a large increase of input until the > output equals +16dBm?? > yes When you make a phased array amp this is the most important figure, since we want to use zero x-ings to get relevant data. Similar to FM. This is in general only possible with differential amps, which have at least F"= 6 to 8dB. So this application really appreciated this design. -- ciao Ban Apricale, Italy Article: 97230 of rec.radio.amateur.homebrew From: Chris Jones Subject: Re: Best way to build fixed 1.6GHz locked oscillator? Date: Mon, 24 Apr 2006 01:01:28 +0100 Message-ID: <124o1ojf88fjhcf@corp.supernews.com> References: <1145768693.594483.54000@e56g2000cwe.googlegroups.com> 3flp wrote: > Hi, > > I'm in the process of designing a simple scalar network analyser. The > synthesizer will use 2 PLLs. One tuning from 1.6 to 2.6GHz and the > second on locked to 1.6GHz. I hope to create a DC to 1GHz output. I'll > use Minicircuits or similar for the broadband VCO. But it seems a > little wastefull to use the same thing for the fixed frequency PLL. So > here's the question, what would you experienced home brew gurus > recommend? > > The oscillator phase noise does not have to be perfect, but it should > not be much worse that the Minicircuits VCOs. The cumbersome > old-fasioned multiplied crystal is not really needed. So what other > options should I look at? > > Thanx for ideas, > 74, > VK3FLP Hi, That sounds like a very interesting project. Can I try to persuade you to make it a vector network analyser? After considering making such a thing, I reckon that at least a third of the work is in making the signal source, and so once you've gone to that trouble, you might as well make a VNA which then allows proper calibration, so your return loss bridge etc. doesn't actually have to have good directivity, just be stable over time. Regarding your question, I think two full PLLs is probably the best solution. If you don't need such wide tuning range for one (or both) of them, you could consider one of the Analog Devices PLL chips with integrated VCO. Usually in a mixer, one of the inputs is driven hard and the other one is driven weakly. If you drive both inputs of your mixer hard then I guess that in addition to the wanted output you'll see the third harmonic of one oscillator mixing with the third harmonic of the other, giving you a spur at three times the wanted output frequency. What are your plans in order to get a clean output? Chris Article: 97231 of rec.radio.amateur.homebrew From: "amdx" References: <4vO2g.18443$6e2.3695@news.edisontel.com> <5d131$444bdf73$45011502$7338@KNOLOGY.NET> Subject: Re: low distortion antenna amp Date: Sun, 23 Apr 2006 19:55:10 -0500 Message-ID: <51b0$444c21e8$45011502$20098@KNOLOGY.NET> > >> > >> I know the lossless feedback based on Dr. Norton (Anzac Electronics) > >> since 1977, when a German M. Martin DJ7VY published in CQ-DL a two > >> stage preamp for 145/440MHz with BFT66 and BFR34A. > >> I modified this amp for my thesis on phased array ultrasonic flaw > >> detectors for lower frequencies. I got much better performance than > >> with the Plessey SL531. F"=1.9dB, and phaseshift change of less than > >> 1deg. over 102dB dynamic range until +16dBm O/P. > >> -- > >> ciao Ban > >> Apricale, Italy > >> > > Hi Ban, > > Interesting that you mention Anzac, I picked up an Anzac AM-962 at a > > hamfest > > many years ago, by the looks of it I thought it might be of the > > lossless feedback > > style, but I never found any confirmation on the net. > > Please help me with your terms. > > > > (1) Definition of F"----? > > > F" is the noise figure. it says how much the noise gets increased in > comparison with a resistor of in this case 50 ohms. > Wow, that's a very low noise figure, do you recall at what frequency you were working? How does your amp compare to the amp here? http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%2 0Amplifiers.pdf Did your design answer any of the questions posed in the article? > > (2) phaseshift change of less than 1deg. over 102dB dynamic > > range until +16dBm O/P. > > > > let me guess > > Very little phaseshift with a large increase of input until the > > output equals +16dBm?? > > > yes > When you make a phased array amp this is the most important figure, since we > want to use zero x-ings to get relevant data. Similar to FM. > This is in general only possible with differential amps, which have at least > F"= 6 to 8dB. So this application really appreciated this design. > -- > ciao Ban > Apricale, Italy > > Article: 97232 of rec.radio.amateur.homebrew From: "James Thompson" Subject: Feedback! Date: Sun, 23 Apr 2006 21:52:03 -0400 Message-ID: Has anyone got a good but cheap circuit to eliminate or surpress feedback. Im making my son some low power fm mikes to use in his church, but they get feedback real easy. Is there a simple notch filter per say that I can add the the mike section of this. My pcb is only 1.5 by 2" right now. Thanks. Article: 97233 of rec.radio.amateur.homebrew From: "Mont" Subject: Class C engineering question Message-ID: <49X2g.63477$F_3.25444@newssvr29.news.prodigy.net> Date: Mon, 24 Apr 2006 02:58:08 GMT Following is a note I received from a friend who earnestly believes that a Class C plate modulated final requires approximately 200% (rather than 50%) of the final power input to achieve 100% modulation. I am interested in any theoretical arguments surrounding this. Thanks, Mont - K0YCN ------------------------------------------- Mont, Here are the numbers as I calculate them to achieve my goal. Since Eimac specs are listed in terms of watts output so I will follow that too. My goal is to be capable of 130% positive peak modulation with 375 watts of carrier output. The Eimac tube manual says a single 4-400 typical operation at 3000 volts on the plate is 630 watts high level plate modulated carrier output. So, 630 watts X 4 = 2520 watts pep capability. So, a more conservative 375 watts X 4 X 1.30 = 1950 watts pos. peak. Dividing that by 2 = 975 watts of peak audio output required from the positive producing modulator tube to make 1950 pos. peak RF output. The 4-125 typical operation indicates 330 watts of AB1 is available. This is a far cry from 975 that I need. On the other hand a 4-400 in AB1 will deliver 1540 watts. The negative vs. positive peaks will be controlled by a broadcast quality Innovonics AM asymmetrical compressor limiter which I am currently using in the shack. The simple unexplained rule of thumb I came to understand early in my early ham days is that a 375 watt transmitter requires 187.5 watts of audio for 100% modulation. So, a 4-125, with 330 watts of capability, should be more than what is needed. In practical terms this is very misleading. That is why I been beating a dead horse for three years while two broadcast engineers could not explain why I could barely attain near 100 modulation. Little did I know that I was driving the pants of the poor 4-125's while trying! Hence, I ordered a custom built filament xfmr that will power two 4-400 modulators. Hope to have all that working in about two weeks. 73, Article: 97234 of rec.radio.amateur.homebrew From: "Mike Andrews" Subject: Re: how to test MC1350P based if amplifier? Date: Mon, 24 Apr 2006 13:12:40 +0000 (UTC) Message-ID: References: <1145882884.089145.211090@g10g2000cwb.googlegroups.com> aadu.adok@gmail.com wrote: > hello, > In my receiver project I have reached to point where I need to test my > IF amplifier. > It's based on one MC1350P stage. > I know it should give me approx 60dB gain. First idea that comes to my > mind is that I should feed it with very weak signal. Am I correct: if > feed it with lets say..1 microvolt, then 60dB of gain should give me 1 > millivolt at the output? > If so..then how can I get such a low level signal (my Hartley > oscillator gives my 1.7 volts PTP). > Any comments? A metal box with good coax connectors on both ends, containing a resistive divider made with _good_ noninductive resistors, is the first thing that comes to mind. You'll also want _good_ coax cable (better than 99% shield coverage) on the jumpers from your Hartley oscillator to the divider box, and from the divider to your amplifier. It probably would be a _very_ good thing to put your oscillator inside a shielded metal box, too, with precautions to minimize signal leakage from the cables and from inside the box. Otherwise you'll be getting some unmeasured leakage signal into your IF amp as well as the signal from the output side of the resistive divider, and that will invalidate your measurements. Good luck, and let us know how you decide to do this. -- Mike Andrews, W5EGO mikea@mikea.ath.cx Tired old sysadmin Article: 97235 of rec.radio.amateur.homebrew From: "Heytubeguy" Subject: FA:GATES 4 H 3KV 1Amp CHOKE+MO PARTS Message-ID: Date: Mon, 24 Apr 2006 16:42:16 GMT Heavy Gates 4H 3KV at 1 A choke (one of two) + more parts and stuff: see at: http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZheytubeguy Tnx heytubeguy Article: 97236 of rec.radio.amateur.homebrew From: You Subject: Re: Class C engineering question References: <49X2g.63477$F_3.25444@newssvr29.news.prodigy.net> <1145849776.388061.168260@j33g2000cwa.googlegroups.com> Message-ID: Date: Mon, 24 Apr 2006 17:01:51 GMT In article <1145849776.388061.168260@j33g2000cwa.googlegroups.com>, "K7ITM" wrote: > Soooo...if the modulator is transformer-coupled, how does the DC input > to the RF amplifier increase when modulation is applied? A transformer > can't couple DC... You really don't know the answer to this? Did you actually pass the Theory Exam? Inquiring minds want to know......... Article: 97237 of rec.radio.amateur.homebrew From: You Subject: Re: how to test MC1350P based if amplifier? References: <1145882884.089145.211090@g10g2000cwb.googlegroups.com> Message-ID: Date: Mon, 24 Apr 2006 17:03:25 GMT In article <1145882884.089145.211090@g10g2000cwb.googlegroups.com>, aadu.adok@gmail.com wrote: > hello, > > In my receiver project I have reached to point where I need to test my > IF amplifier. > It's based on one MC1350P stage. > > I know it should give me approx 60dB gain. First idea that comes to my > mind is that I should feed it with very weak signal. Am I correct: if > feed it with lets say..1 microvolt, then 60dB of gain should give me 1 > millivolt at the output? > > If so..then how can I get such a low level signal (my Hartley > oscillator gives my 1.7 volts PTP). > > Any comments? > that's what attenuator stacks are for.......... Dah..... Article: 97238 of rec.radio.amateur.homebrew From: Allisonnospam@nouce.bellatlantic.net Subject: Re: how to test MC1350P based if amplifier? Message-ID: References: <1145882884.089145.211090@g10g2000cwb.googlegroups.com> Date: Mon, 24 Apr 2006 19:03:26 GMT On 24 Apr 2006 05:48:04 -0700, aadu.adok@gmail.com wrote: >hello, > >In my receiver project I have reached to point where I need to test my >IF amplifier. >It's based on one MC1350P stage. > >I know it should give me approx 60dB gain. First idea that comes to my >mind is that I should feed it with very weak signal. Am I correct: if >feed it with lets say..1 microvolt, then 60dB of gain should give me 1 >millivolt at the output? An aside: depending on input match and output match you may see as little as 47Db and still be working properly. >If so..then how can I get such a low level signal (my Hartley >oscillator gives my 1.7 volts PTP). While someone has answered you. I'll reiterate. Build the osc in s shielded box. Then from it's output connector you add attenuators as needed to keep from overloading the IF amp. Depending on what you have you them meaure the input and output levels to calculate the gain. >Any comments? First make sure the IF is stable and not oscillating! That much gain in a small space there is risk for that if care is not taken. The real challenge is measuring the small signals! Hint: use the higest input that does not cause overload as even the best scopes rarely go below 5mV/Div One way to meaure amplifier gain is to start with a lagre but well shielded signals source and use a lot of attenuation to keep from overloading the amplifier. Procedure is to use enough output >from the attenuator stack to get say .2VPP from the amplifer into the test load. Then you remove the amplifier and remove attenuation until you get the same voltage into the test load. The difference in attenuation is your gain (at that working impedence). one hint: while it seems awkward building all your reciever blocks for 50ohm inputs and outputs allows both convenient testing and use. Each block such as an IF then can be placed in it's own shielded case and interconnected with coax cable. The advantage then is better performace without unintended interactions and any block can be later replaced with an improved one if desired. I suggest you build a shielded osc. Also build a step attenuator (or several ) so you can stack up as much as 100db or attenuation or as little as you need. I have two switch selectable attenuators that go from 0-60db I can use for up to 200mhz work. Allison Article: 97239 of rec.radio.amateur.homebrew From: "Joel Kolstad" Subject: Re: Favorite low power receiver ICs? Date: Mon, 24 Apr 2006 14:49:37 -0700 Message-ID: <124qi13fb3bkoea@corp.supernews.com> References: <124ig4j152ptd07@corp.supernews.com> Hi Tim, "Tim Wescott" wrote in message news:IpCdnVr354Oa-NTZnZ2dnUVZ_tWdnZ2d@web-ster.com... > Hey, if you find one let me know! Yeah, will do! > Have you considered looking at one of the obsolete-components suppliers? Not yet, I'll check there shortly. > Maybe we could hire Jim Thompson and start a company... I could use about 1000 of them right about now... perhaps even a couple thousand. But I suspect the quantity would have to be in at least the tens of thousands if not hundreds of thousands before anyone would be willing to build something new... Article: 97240 of rec.radio.amateur.homebrew Message-ID: <444D52E5.9C4C7B9A@earthlink.net> From: "Michael A. Terrell" Subject: Re: Favorite low power receiver ICs? References: <124ig4j152ptd07@corp.supernews.com> <124qi13fb3bkoea@corp.supernews.com> Date: Mon, 24 Apr 2006 22:37:44 GMT Joel Kolstad wrote: > > Hi Tim, > > "Tim Wescott" wrote in message > news:IpCdnVr354Oa-NTZnZ2dnUVZ_tWdnZ2d@web-ster.com... > > Hey, if you find one let me know! > > Yeah, will do! > > > Have you considered looking at one of the obsolete-components suppliers? > > Not yet, I'll check there shortly. > > > Maybe we could hire Jim Thompson and start a company... > > I could use about 1000 of them right about now... perhaps even a couple > thousand. But I suspect the quantity would have to be in at least the tens of > thousands if not hundreds of thousands before anyone would be willing to build > something new... Check with Lansdale to see if they can help. They buy the rights to manufacture a lot of EOL parts. http://www.lansdale.com/ -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida Article: 97241 of rec.radio.amateur.homebrew From: "Tom Holden" References: Subject: Re: The Perfect Gift: A Tool Box Message-ID: Date: Mon, 24 Apr 2006 23:02:30 -0400 "Fred McKenzie" wrote in message news:fmmck-1704062318190001@acac1c7d.ipt.aol.com... > In article , Highland Ham > wrote: > >> What about Posidrive screwdrivers ? These are similar to Philips type of >> screwdrivers but have additional 'notches' (if that is the correct word) >> for better grip . The relevant screw heads are accordingly. > > Frank- > > I've heard of Posidrive. I think they are used in an old Hewlett Packard > counter I have. However, the tool dealers I asked had never heard of > them. I ended up using a common Phillips driver for my counter. > > Certainly Posidrive would be a better choice where they are more commonly > used. > > Fred In that vein, Canadians would have Robertson screwdrivers in their basic toolbox for home use. Described, with history, at http://en.wikipedia.org/wiki/Robertson_screwdriver . Tom Article: 97242 of rec.radio.amateur.homebrew Message-ID: <444DA7D0.F4A35232@earthlink.net> From: "Michael A. Terrell" Subject: Re: The Perfect Gift: A Tool Box References: Date: Tue, 25 Apr 2006 04:39:30 GMT Tom Holden wrote: > > "Fred McKenzie" wrote in message > news:fmmck-1704062318190001@acac1c7d.ipt.aol.com... > > In article , Highland Ham > > wrote: > > > >> What about Posidrive screwdrivers ? These are similar to Philips type of > >> screwdrivers but have additional 'notches' (if that is the correct word) > >> for better grip . The relevant screw heads are accordingly. > > > > Frank- > > > > I've heard of Posidrive. I think they are used in an old Hewlett Packard > > counter I have. However, the tool dealers I asked had never heard of > > them. I ended up using a common Phillips driver for my counter. > > > > Certainly Posidrive would be a better choice where they are more commonly > > used. > > > > Fred > > In that vein, Canadians would have Robertson screwdrivers in their basic > toolbox for home use. Described, with history, at > http://en.wikipedia.org/wiki/Robertson_screwdriver . > > Tom I despise Robertson screws, along with the "Clutch head" screws. Every time I run into either of them, someone has put them in with a worn bit that strips the head and makes them almost impossible to remove. I've used surface grinders, drills, and a cutting torch to remove them to make repairs. I generally replace them with hex head screws and make sure that I always inspect the bit before I start a job. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida