Date: Mon, 28 Mar 94 04:30:20 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 #76 To: Ham-Homebrew Ham-Homebrew Digest Mon, 28 Mar 94 Volume 94 : Issue 76 Today's Topics: clo Microwave Filter Help Needed MuRata SSB Filters Subscribe 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: 27 Mar 94 17:45:27 GMT From: agate!howland.reston.ans.net!newsserver.jvnc.net!raffles.technet.sg!ntuix!ntuvax.ntu.ac.sg!asirene@ucbvax.berkeley.edu Subject: clo To: ham-homebrew@ucsd.edu Hi, COncerning the 20m receiver noise article I posted earlier, I have now determined the source of that noise to be the MC1350 IF post filter amplifier. Can anyone suggest anyway to quieten this very noisy part? At the input transformer a 200 ohm resistor is set in parallel and at the output, a 1k in parallel with the output transformer. Both input's and outputs are in balanced configuration. Would appreciate any advise on this MC1350 noise. Is there any other component I can use in its place which would lower the noise. It appears as a background hiss (white noise) and since it is post-IF filtering, it is quite audible and irritating though not worse than the atmospheric noise. I am aware of atmospheric noise conditions but I ask this not because the present situation is unbearable/unusable but I'd like to IMPROVE the system as far as possible. SO regardless of whether this is going to provide any benefit in practice, I'd like to understand the theory at least, for getting rid of the noise from the MC1350. Of course I know that filtering or adding a filter helps but that does not deal with the noise source, merely cuts it out. Tks. in advance. 73, Daniel ------------------------------ Date: 27 Mar 1994 01:48:05 -0500 From: ihnp4.ucsd.edu!agate!usenet.ins.cwru.edu!gatech!news.ans.net!hp81.prod.aol.net!search01.news.aol.com!not-for-mail@network.ucsd.edu Subject: Microwave Filter Help Needed To: ham-homebrew@ucsd.edu In article <2n33hp$5ec@nntp2.Stanford.EDU>, stevem@w6yx.stanford.edu (Steve Muther) writes: You're linking ATV repeaters in the Bay Area? Sounds cool. Can I hit an ATV repeater from the flats of Berkeley? Btw, my brother has been buying up microwave junk from surplus stores. We don't have a station together yet, but he does have some kind of detector and signal generator. He and I are both licensed and, I'm at least, kind of looking people who really knows this stuff. ------------------------------ Date: 26 Mar 94 21:24:10 GMT From: dog.ee.lbl.gov!agate!usenet.ins.cwru.edu!nshore!seastar!jjw@ucbvax.berkeley.edu Subject: MuRata SSB Filters To: ham-homebrew@ucsd.edu As quoted from by ap570@FreeNet.Carleton.CA (John Spittle): > > > MuRata CFM455J1 (2.6 KHz BW) > or > MuRata CFJ455K5 (2.4 KHz BW) > > - filters needed for QRP club transceiver project. Can anyone > name a supplier (in Canada or US) who carries a stock? We are > looking for at least 30. "Derry" VE7QK Try Digikey's TOKO HCFM2-455A filter, -6db bw of 4kHz. Digikey part # is TK2330, cost is $25.20 for 10, or $189 for 100. Digikey order number is 800-344-4539. I've used them before - they have slightly different shape but to the same job about as well as the Murata ones, and they're a *lot* easier to find. If you're using a pre-designed board and *must* have the Murata filter, try Penstock. I don't have their # handy, but they are in all the radio trade rags (RF Design, microwaves&rf, microwave journal, etc). -- While (its_not_working()) John Welch, N9JZW mess_with_it(); jjw@seastar.org ------------------------------ Date: 28 Mar 94 02:14:36 GMT From: news-mail-gateway@ucsd.edu Subject: Subscribe To: ham-homebrew@ucsd.edu Vincent Ferme, Toronto, Ontario, Canada. ------------------------------ End of Ham-Homebrew Digest V94 #76 ****************************** ******************************