Date: Thu, 12 May 94 04:30:19 PDT 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 #126 To: Ham-Homebrew Ham-Homebrew Digest Thu, 12 May 94 Volume 94 : Issue 126 Today's Topics: INSTRUCTION/OPERATORS MANUALS up for grabs: MOSFET Power Amp Schematics/Info ??? Need info about packet Ham Radio - FAQ anywhere? UHF Power amps. UHF Push/Pull design ? Wanted : Cheap, available varacter diode source 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: 11 May 1994 17:45:29 GMT From: ihnp4.ucsd.edu!news.service.uci.edu!mothra.nts.uci.edu!lockhart@network.ucsd.edu Subject: INSTRUCTION/OPERATORS MANUALS up for grabs: To: ham-homebrew@ucsd.edu I have the following INSTRUCTION/OPERATORS MANUALS up for grabs: HY-GAIN THUNDERBIRD (TH3Mk30 THREE ELEMENT HAM ANTENNA CDE HAM II ROTOR These INSTRUCTION/OPERATORS MANUALS are in various states of condition. Some are in good condition and some are in poor condition. The intent is to give these INSTRUCTION/OPERATOR MANUALS to an individual or entity who ACTUALLY has the equipment. The first person to send me e-mail gets the booty. Please send a separate e-mail request for each INSTRUCTION OR OPERATORS MANUAL. You will be asked to send a SASE (large manila or other envelope) with the appropriate amount of U.S. postage to me c/o the address in my .sig file. Good luck to one and all. 73, ~jack_ /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ | Jack C. Lockhart << SNAILMAIL | | Radio Systems Engineer E-MAIL > LOCKHART@uci.edu | |Office of Academic Computing - ECS !BANG! > ...!ucbvax!ucivax!lockhart | | 2209 Central Plant Building HAM > WD6AEI | | University of California, Irvine AMPR > WD6AEI@n0ary.#nocal.ca.usa.na | | Irvine, CA 92717-5475 VOICE > (714) 856-8477 | | U.S.A FAX > (714) 725-2270 | \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/ "And in the beginning there was nothing. And God said, 'let there be light'. And there was still nothing, BUT you could see IT!" -Anonymous / o o o o o o o . . . ________________________________ _____=======____\_ o _____ | | | | .][__n_n_|DD[ ====_____ | #include | | | >(________|__|_[_________]_|______________________________|_|_______________|_ _/oo OOOOO oo` ooo ooo 'o^o^o o^o^o` 'o^o o^o` -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/ ------------------------------ Date: Tue, 10 May 1994 11:26:28 GMT From: ihnp4.ucsd.edu!galaxy.ucr.edu!library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!pipex!uknet!dcl-cs!ega066@network.ucsd.edu Subject: MOSFET Power Amp Schematics/Info ??? To: ham-homebrew@ucsd.edu In class-C type operation you won't find the drain voltage swinging negative. Ignoring the FET on-resistance, the average drain voltage would simply be the DC supply level, V, and in operation the drain voltage would swing from 0V to 2V. Practically, the device on-resistance limits the downward swing to a few volts, however. Therefore it's better to use high supply voltages for FETs (ie. higher than 12V), to increase the voltage swing available. Quite a good way to drive FETs is a simple complementary emitter-follower pair. This configuration can provide sufficient current to charge/ discharge the effective gate capacitance, which can be large for power devices being switched on/off. The only problem is getting hold of a PNP device with high ft. It does save messing about with matching networks, though. Motorola note AR-141 in their RF Device book give good info on this subject, with regard to driving class-D/E DMOS FET stages. For low power HF operation, switching FETs have a lot going for them. They are very easy to bias, cheap, they don't exhibit thermal runaway and it's easy to drive them. Good luck,, Simon G0GWA. ------------------------------ Date: Thu, 12 May 1994 01:05:28 From: ihnp4.ucsd.edu!munnari.oz.au!newshost.anu.edu.au!slipr6.anu.edu.au!Martin.Stephenson@network.ucsd.edu Subject: Need info about packet Ham Radio - FAQ anywhere? To: ham-homebrew@ucsd.edu I am looking for any info about packet ham radio. Like where can I find an FAQ? :-) I am pretty well after enough information to get someone started with packet ham radio. My Father was a keen Radio Ham until he moved to Egypt. The easiest way to access the Internet from Egypt would be via Ham radio. The Egyptian telecommunications system stopped being developed sometime in the stone age, and so normal access methods are not economically possible. I thought this group might be a good place to start to find out more about packet ham radio. Thanks for any help. Martin.Stephenson@anu.edu.au ------------------------------ Date: Tue, 10 May 1994 13:08:03 From: ihnp4.ucsd.edu!munnari.oz.au!foxhound.dsto.gov.au!fang.dsto.gov.au!yoyo.aarnet.edu.au!news.adelaide.edu.au!rem-ppp-00.cs.adelaide.edu.au!jfk@network.ucsd.edu Subject: UHF Power amps. To: ham-homebrew@ucsd.edu Hi, Does anyone know of any good articles or books with practical circuits for the construction of power amps for 70cm. Also any hints on reducing receiver desense when TX on UHF and RCV on 2.4Ghz, Oscar 13 Mode S. 73's ------------------------------ Date: 10 May 1994 09:48:38 GMT From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!howland.reston.ans.net!math.ohio-state.edu!jussieu.fr!univ-lyon1.fr!elendir@network.ucsd.edu Subject: UHF Push/Pull design ? To: ham-homebrew@ucsd.edu Hi ! I have been scared by the price of the latest VHF/UHF all mods rigs. So I decided to build my own. However, I©m looking for a UHF Push-Pull design. The very problem I have is in the design of the 180 degrees phase shifter. In VHF, I can use a small transformer with a ground tap in the middle, but this cannot be applied to UHF. I thought about a printed transformer or a transistor operating as an inverter. Neither those seem really satisfactory. Does someone have any clue ? Thanks and 73 ! Vince. -- PSG --- Paris SG football club. | Ham radio call : F1RCS ----------------------------------------------------------------------- ENST - Ecole Nationale Superieure des Telecommunications, Paris, France ------------------------------ Date: Wed, 11 May 1994 21:02:46 +800 From: ihnp4.ucsd.edu!newshub.sdsu.edu!nic-nac.CSU.net!usc!howland.reston.ans.net!nctuccca.edu.tw!news.cc.nctu.edu.tw!rs540.ncu.edu.tw!ccvax.sinica.edu.tw!bodafu@network.ucsd.edu Subject: Wanted : Cheap, available varacter diode source To: ham-homebrew@ucsd.edu dean@splinter.coe.neu.edu (Dean Gelabert) writes: > Hi: > I'd like to begin experimenting w/ varacter diodes. Can anyone > recommend an inexpensive, readily available, easy to work w/ > device? Where can I get a few to play with? > > -Dean Dean Any diode will act as a variable cap when reverse biased. The doohickies sold as 'varacters' have a wider response and more closely specified properties, but for experimentation any diode will do. I had good results fine tuning a SW receiver using the first small-signal diode I grabbed out of the junk box. The non-conducting region in the reverse-biased diode acts as a dielectric between the terminals; this is the cap. Varying the voltage changes the thickness of the non-conduction region, and thus changes the capacitance. David ____________________________________________________________________________ David L. Bergart bodafu@ccvax.sinica.edu.tw bodafu@TWNAS886.bitnet Copy oddity^h^h^h^h^h^heditor, Botanical Bulletin of Academia Sinica, Taiwan ____________________________________________________________________________ ------------------------------ End of Ham-Homebrew Digest V94 #126 ******************************