Date: Fri, 11 Feb 94 04:30:50 PST From: Ham-Homebrew Mailing List and Newsgroup Errors-To: Ham-Homebrew-Errors@UCSD.Edu Reply-To: Ham-Homebrew@UCSD.Edu Precedence: Bulk Subject: Ham-Homebrew Digest V94 #26 To: Ham-Homebrew Ham-Homebrew Digest Fri, 11 Feb 94 Volume 94 : Issue 26 Today's Topics: 2m/70cm linear - circuit wanted BALUN FOR 2-M YAGI Microphones & motorcycle helmets Project #15: A Spark-Gap Transmitter QRP shopping list (3 msgs) Transceiver headset Varactor tuned VFOs (2 msgs) Yaesu MH-29 speaker/mike audio levels Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Homebrew Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: 8 Feb 94 16:40:11 GMT From: ogicse!cs.uoregon.edu!sgiblab!spool.mu.edu!darwin.sura.net!fconvx.ncifcrf.gov!mack@network.ucsd.edu Subject: 2m/70cm linear - circuit wanted To: ham-homebrew@ucsd.edu In article patrick_tatro@stortek.com (Patrick Tatro) writes: >In article <1994Feb8.080757.1530@mnemosyne.cs.du.edu> dtock@nyx.cs.du.edu (David Tock) writes: >>From: dtock@nyx.cs.du.edu (David Tock) >>Subject: 2m/70cm linear - circuit wanted >>Date: Tue, 8 Feb 94 08:07:57 GMT > >David > Communication Concepts Inc. has a kit for 2 meters that sells for $119 >that can take 5 watts to 50 or 60 watts and they also sell 70cm linear kits >for $159. I don't know if this fits your needs, but I built the 2 meter >amplifier and it works great. If you need their address, Email me. > >73's >Patrick Tatro N0WCG > Really? I know someone has a kit, but it was 28V (my car is 12V). Are these 12V and do they have the R/R relays for this price.? Joe Mack NA3T mack@ncifcrf.gov ------------------------------ Date: Wed, 9 Feb 94 20:49:59 GMT From: unogate!news.service.uci.edu!usc!howland.reston.ans.net!math.ohio-state.edu!cs.utexas.edu!swrinde!sgiblab!twg.com!eco.twg.com!psinntp!newsserver.pixel.kodak.com!kodak!ornitz@@mvb.saic.com Subject: BALUN FOR 2-M YAGI To: ham-homebrew@ucsd.edu In article <2j64ii$5ip@granny.mdd.comm.mot.com> shane@mdd.comm.mot.com (Hugh Shane N7UAX) writes: >Can anyone suggest a design for matching a 50-ohm coax feed to a six beam, >2 meter Yagi. The balun designs I've seen all seem to be restricted to >frequencies less than 100MHz. There must be a classic technique, I just >can't find it! The classic VHF balun technique is the quarter-wave sleeve balun. In old days these were often called beer-can baluns, so named because steel beer cans were soldered together to form the outer sleeve. KLM and a few other companies sold these commercially but they are easy to build with copper tubing and pipe. Design information can often be found in the older ARRL VHF manuals. 73 Barry WA4VZQ ----------------- | ___ ________ | Dr. Barry L. Ornitz WA4VZQ | | / / | | Eastman Chemical Company | | / / | | ECC Research Laboratories, Engineering Research Div. | |< < K O D A K| | Process Instrumentation Research Laboratory | | \ \ | | P. O. Box 1972, Building 167B | |__\ \________| | Kingsport, TN 37662 (615/229-4904, FAX 615/229-4558) | | INTERNET: ornitz@kodak.com ----------------- Eastman Chemical Company is no longer a part of Kodak, now being an independent company. Kodak is letting us use her Internet connection until we get our own. ------------------------------ Date: Mon, 7 Feb 1994 20:56:55 GMT From: agate!howland.reston.ans.net!vixen.cso.uiuc.edu!sdd.hp.com!col.hp.com!srgenprp!alanb@network.ucsd.edu Subject: Microphones & motorcycle helmets To: ham-homebrew@ucsd.edu Tim Ikeda (timi@mendel.berkeley.edu) wrote: : I'm wondering if anyone has a good system for reducing the wind : and engine noise picked up by full-faced helmet microphones. They're expensive, but the noise-cancelling mikes used in airplanes do an incredible job. AL N1AL ------------------------------ Date: Tue, 8 Feb 1994 21:14:14 +0000 From: ihnp4.ucsd.edu!sdd.hp.com!swrinde!cs.utexas.edu!howland.reston.ans.net!pipex!demon!dis.demon.co.uk!kanga.demon.co.uk!dick@network.ucsd.edu Subject: Project #15: A Spark-Gap Transmitter To: ham-homebrew@ucsd.edu HI what is the "boatanchors" group? Info appreciated 73 de Dick ------------------------------ Date: 9 Feb 1994 21:57:26 GMT From: koriel!newscast.West.Sun.COM!abyss.West.Sun.COM!sunspot!myers@ames.arpa Subject: QRP shopping list To: ham-homebrew@ucsd.edu In article 13644@tekig7.PEN.TEK.COM, royle@tekig6.PEN.TEK.COM (Roy W Lewallen) writes: > > >myers@pongo.West.Sun.COM (Dana Myers ): >>> >>>Transistors >>[...] >>>2N4416+ >>[...] >>>MPF102+ > >>These are essenitally the same transistor, at least as far as QRP projects >>go. . . > >Although usually true, there are a couple of common applications >where substituting an MPF102 for a 2N4416 might cause a problem. These >JFETs are commonly used as an oscillator, either Harley or Colpitts. In >these simple oscillators, the oscillator output amplitude is directly >related to the individual device's pinchoff voltage. The MPF102 has much >looser specifications, so in some cases will deliver too small (or large) >a signal when used in one of these oscillators in place of a 2N4416. Of >course, you can make up the difference in a following stage if it's a >one-off design or you're willing to put in an adjustment. There have been a few letters published in QST mentioning the device-to-device variation of the MPF102 can result in considerable performance changes. In particular, the use of the MPF102 in an oscillator is rather mentioned; you just about have to hand-select a FET out of a batch for best/correct output. I've never really looked at it hard, but most oscillator circuits that use a JFET include a diode from the gate to ground. This obviously serves to clamp the gate voltage before the gate/source diode conducts (as long as the diode is fast enough :-) ), and also will build a DC offset on the coupling capacitor from the tank circuit to the gate. This DC bias would appear to, and is said to, provide an AGC action is stabilizing the oscillator output amplitude. What comes to mind, is this action adequate to compensate for common device variations? >The other application where you might have a problem is using the MPF102 >for a common-gate RF amplifier. A typical application runs the JFET at >Idss and couples the signal in through a 1:4 impedance ratio transformer. >With the 2N4416, this will result in an input SWR of 1.5 or less; the >MPF102 can present a mismatch as high as 2.5:1 because of its looser specs. >This may not cause a problem, but it could reduce stage gain. Or if the >common-base stage follows a filter, it could result in degraded filter >performance. Yup; I always recommend using a J310 for such an application since (a) the specs are tighter and increase chance of repeatability and (b) the fairly high forward Gm of the J/U310 provides a pretty good match directly to 50-75ohms. --- * Dana H. Myers KK6JQ, DoD 466 | Views expressed here are * * (310) 348-6043 | mine and do not necessarily * * Dana.Myers@West.Sun.Com | reflect those of my employer * * This Extra supports the abolition of the 13 and 20 WPM tests * ------------------------------ Date: 10 Feb 94 18:27:40 GMT From: ogicse!news.tek.com!tekig7!tekig6!royle@network.ucsd.edu Subject: QRP shopping list To: ham-homebrew@ucsd.edu myers@cypress.West.Sun.COM (Dana Myers ): >I've never really looked at it hard, but most oscillator circuits that use >a JFET include a diode from the gate to ground. This obviously serves to >clamp the gate voltage before the gate/source diode conducts (as long as the >diode is fast enough :-) ), and also will build a DC offset on the coupling >capacitor from the tank circuit to the gate. This DC bias would appear to, >and is said to, provide an AGC action is stabilizing the oscillator output >amplitude. What comes to mind, is this action adequate to compensate for >common device variations? No. The diode limits the positive excursion of the gate signal. Pinchoff determines the negative excursion. Roy Lewallen, W7EL roy.w.lewallen@tek.com ------------------------------ Date: 8 Feb 1994 23:16:12 GMT From: ihnp4.ucsd.edu!sdd.hp.com!swrinde!sgiblab!sgigate.sgi.com!olivea!koriel!newscast.West.Sun.COM!abyss.West.Sun.COM!pongo!myers@network.ucsd.edu Subject: QRP shopping list To: ham-homebrew@ucsd.edu In article randolph@est.enet.dec.com (Tom Randolph) writes: > >With flea market season rapidly approaching here in the NE, I sat down with >W1FB's QRP Notebook and went through all the schematics to compile this parts >list. This is everything that appears 3 or more times in the book, except for >important stuff like chips. Buy lots of it if it has a + next to it. >So now you all can fill up your QRP junk boxes... > >Transistors [...] >2N4416+ [...] >MPF102+ These are essenitally the same transistor, at least as far as QRP projects go. I stocked up on J310s from Hamilton/Hallmark, which is at least as good as the 2N4416/MPF102, for $.34/ea brand-new. -- * Dana H. Myers KK6JQ, DoD 466 | Views expressed here are * * (310) 348-6043 | mine and do not necessarily * * Dana.Myers@West.Sun.Com | reflect those of my employer * * This Extra supports the abolition of the 13 and 20 WPM tests * ------------------------------ Date: 10 Feb 1994 15:29:28 GMT From: concert!ecsgate!bruce.uncg.edu!hamlet!henderdx@decwrl.dec.com Subject: Transceiver headset To: ham-homebrew@ucsd.edu I have a question that is possibly a little out of place here in your news group, but for lack of a better place to post... I'm not a HAM-ster, but I'd like to build a headset (Microphone/earphones) w/ a built in transmitter reciever for use w/ my computer. I'd like it as compact as possible. i.e. all in the head set wo/ a battery pack. This will require at least two (three if I decide to go stereo) IC's (RS-232), plus possibly a very small pre-amp for the mic (this will depend on output levels on the mic and required input levels at the IC.) Does anyone know where I can get a design for such a project? Or better yet, has anyone ever built that sort of thing? Any info, hints, tips, tricks, or possible "hang-ups" would be greatly appreciated. -- David Henderson henderdx@hamlet.uncg.edu ------------------------------ Date: Fri, 11 Feb 1994 01:08:19 GMT From: cs.utexas.edu!news.unt.edu!news.oc.com!news.kei.com!eff!news.umbc.edu!europa.eng.gtefsd.com!emory!kd4nc!ke4zv!gary@uunet.uu.net Subject: Varactor tuned VFOs To: ham-homebrew@ucsd.edu In article tomb@lsid.hp.com (Tom Bruhns) writes: >Actually, in a sense, there are a whole lot of them: as >VCO's in PLLs in things like handhelds. As someone else >pointed out, they aren't particularly temp stable, but a >bit of feedback can solve that problem. And you can >frequency or phase lock them quite easily: frequency >locking is especially easy, since if you assume that the >VCO won't drift too much in a single count period (say >1/10 second), you only have to keep track of the least >significant bits to get enough info for a correction. >Continuing the example, 4 bits of count could correct >+/- 70Hz each 1/10 second, and if you feed the correction >into an integrator, it will track. If you have a drift >that large, you probably need to work on the open-loop >characteristics anyway, before closing the loop. Anyway, >the result would be a 10Hz reference, a 4 bit counter, >a 4 bit latch to save the "desired", a 4 bit adder >(actually subtracter) to find the error, a 4 bit DAC >(4 resistors driven from the CMOS output of the adder), >and an integrator. You could put all that in a FPGA >(including the reference generator and timing stuff) >pretty trivially. But you can also do it with common >parts that have been available since the late '60's... Hmmm, this scheme would allow analog tuning that "snaps" to 10 Hz increments with the long term drift characteristics of a crystal reference. Neat. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | ------------------------------ Date: 11 Feb 1994 03:48:37 GMT From: agate!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!odin!trier@network.ucsd.edu Subject: Varactor tuned VFOs To: ham-homebrew@ucsd.edu In article , Tom Bruhns wrote: >Continuing the example, 4 bits of count could correct >+/- 70Hz each 1/10 second, and if you feed the correction >into an integrator, it will track. Neat! One of those Microchip PICs could do the job nicely, replacing the adder and 10 Hz reference. (Software timing loops could do the job.) Are there any other clever ways to reduce this scheme to fewer off-the- shelf components? Stephen -- Stephen Trier KB8PWA Dave: [H]as anyone ever met a Zamboni driver? Other: trier@ins.cwru.edu Mike: The next version of OS/2 will include a Home: sct@po.cwru.edu Zamboni driver. Let's see Microsoft top that! (dave@cs.arizona.edu & miked@vnet.ibm.com) ------------------------------ Date: 11 Feb 1994 03:52:18 GMT From: dog.ee.lbl.gov!agate!kabuki.EECS.Berkeley.EDU!kennish@network.ucsd.edu Subject: Yaesu MH-29 speaker/mike audio levels To: ham-homebrew@ucsd.edu I just got the fancy speaker mike for the Yaesu FT-530 HT with the digital readout and all that. However, it seems to have a very low audio level on transmit (i.e. low deviation). I literally have to shout into the mike to get the same audio level as that obtained by the built in mike on the HT. Anyone else have this problem or do I have a lemon??? -thanks in advance es 73 Ken ------------------------------ Date: Tue, 8 Feb 1994 21:45:04 GMT From: ihnp4.ucsd.edu!sdd.hp.com!cs.utexas.edu!howland.reston.ans.net!paladin.american.edu!darwin.sura.net!fconvx.ncifcrf.gov!mack@network.ucsd.edu To: ham-homebrew@ucsd.edu References , , win.su Subject : Re: 2m/70cm linear - circuit wanted In article patrick_tatro@stortek.com (Patrick Tatro) writes: >In article mack@ncifcrf.gov (Joe Mack) writes: >>From: mack@ncifcrf.gov (Joe Mack) >>Subject: Re: 2m/70cm linear - circuit wanted >>Keywords: Kits >>Date: Tue, 8 Feb 1994 16:40:11 GMT > >>12V and do they have the R/R relays for this price.? >> Joe Mack NA3T >> mack@ncifcrf.gov >Joe > The kit I built was 12V - I don't know what you mean by R/R relays - The >amp was a mono bander - It was real easy to assemble - It took abt 5 hours to >assemble and 1 hour to tune the SWR's . If you need more info contact >Communication Concepts Inc. >508 Millstone Drive >Beavercreek, Ohio > 45434-5840 > >ph 513-426-8600 > >73's >Patrick Tatro N0WCG > > > Sorry that was T/R relays (I didn't see it till the next round). I just called them - Their UHF amp is 28V, but they are hoping to have one for 12V by Dayton. I think their VHF amp used to be 28V, but now it's 12V. I'll keep me eyes out. Thanks for the tip. Joe NA3T mack@ncifcrf.gov ------------------------------ End of Ham-Homebrew Digest V94 #26 ****************************** ******************************