Date: Sun, 31 Oct 93 04:30:27 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 V93 #89 To: Ham-Homebrew Ham-Homebrew Digest Sun, 31 Oct 93 Volume 93 : Issue 89 Today's Topics: CB to 40 Meter Conversion? how to: spl meters Microwave Work at 5 or 10GHz 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: 29 Oct 1993 00:59:45 GMT From: spool.mu.edu!howland.reston.ans.net!usenet.ins.cwru.edu!cleveland.Freenet.Edu!al838@decwrl.dec.com Subject: CB to 40 Meter Conversion? To: ham-homebrew@ucsd.edu Has anyone attempted to convert an SSB CB radio for use on 40 meters? Although it would not be a trivial task to change all the tuned circuits in the receiver front end and in the transmitter driver and final amplifiers, it doesn't seem like the conversion would be that difficult. I looked into this briefly a couple of years ago and it seems feasible for those radios designed using the single crystal method of synthesis. Specifically, I was considering a Radio Shack model TRC-453. ---Eric -- Eric Grabowski, WA8HEB al838@cleveland.freenet.edu Chagrin Falls, Ohio ------------------------------ Date: Sat, 30 Oct 1993 13:58:50 GMT From: news.service.uci.edu!paris.ics.uci.edu!csulb.edu!library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!math.ohio-state.edu!cyber2.cyberstore.ca!nwnexus!jhgrud!eskimo!mann@network. Subject: how to: spl meters To: ham-homebrew@ucsd.edu In article <1993Oct29.002344.1@bcvms.bc.edu>, lewisbc@bcvms.bc.edu writes: > What would be necessary to make an inexpensive spl meter? > And if made, how would you calibrate it? any info would be > useful > Assuming you mean Sound Pressure Level meter: I have given this one some thought on occasion (like when my kids have their stereo on :-) ). If I remember right, a log scale meter and amp-mic combination will get you close. Where I get hung up is the freq response. Standard meters have 3 scales, one follows the freq response of a normal human ear, one is linear, I forget what the 3rd is. As for calibrating the level, I'd use a calibrated meter as a reference. If you want to get super accurate, I >BELIEVE< the reference standard is 0dB SPL = 0.0002 dyne/meter^2. When I was working in a lab where we did a lot of this type of measurement, the microphone elements we bought were very pricey but we were trying for dynamic ranges around 100dB and very accurate freq response. I guess it all comes down to how accurate do you want to be. -- Tom "Old" Mann KD9NL/7 Kirkland, Wash. ------------------------------ Date: 27 Oct 93 22:21:39 CST From: library.ucla.edu!agate!spool.mu.edu!caen!kuhub.cc.ukans.edu!wsuhub.uc.twsu.edu!mwreed@network.ucsd.edu Subject: Microwave Work at 5 or 10GHz To: ham-homebrew@ucsd.edu Is anyone doing any work at 5 or 10GHz? If your working with it or know someone that is I'd like to visit with you. mwreed@wsuhub.uc.twsu.edu n0pco@k0hyd.scks.ks.usa.noam thanks ------------------------------ Date: Fri, 29 Oct 1993 21:01:23 GMT From: sdd.hp.com!swrinde!elroy.jpl.nasa.gov!usc!howland.reston.ans.net!agate!headwall.Stanford.EDU!Csli!kawai@network.ucsd.edu To: ham-homebrew@ucsd.edu References <1993Oct29.002344.1@bcvms.bc.edu>, , <2arr3h$cjg@reznor.larc.nasa.gov>anf Subject : Re: how to: spl meters lewisbc@bcvms.bc.edu asks: | What would be necessary to make an inexpensive spl meter? And if made, | how would you calibrate it? any info would be useful N1AL answers: | Assuming "spl" means "sound pressure level" it wouldn't be hard ... | Borrow a lab-grade SPL meter to calibrate. Scott answers: | ... it's actually not an easy task ... Radio Shack, of all folks, makes | an acceptable SPL meter for about $30 ... Better calibrate it before | using, though. Depending on what you want to use it for, you might like to buy a unit instead of making your own. Recommendations for test and measurment equipment must be put in context -- namely, what is the application? I use an el cheapo unit, called the Extech 407735. This is a digital sound level meter, accurate to +/- 2 dB, with two ranges (lo: 35 - 100 dB, hi: 65 - 130 dB), A and C weightings with 0.1 dB resolution, fast and slow response, built-in calibration at 94 dB, 3 and 1/2 digit LCD, peak hold, meets ANSI type 2 standards, weighs 7.6 oz, made in Taiwan, uses 9 V battery, built-in mic, case included, list price $199, street price $175. I bought mine from EIL Instruments. They have an office in LA -- 6212 Peachtree Street, Los Angeles, CA 90040, (213)685-7020, fax (213)721-5751. The new Radio Shack digital SPL meter looks good, too. As I understand it, it doesn't come with calibration tools, so you'll need to get your own. 73 DE N6UOK ----------------- Speech Research Program, SRI, Menlo Park, CA 94025-3493 USA --- Goh Kawai --- work:(415)859-2231 fax:(415)859-5984 home:(415)323-7214 ----------------- internet: kawai@speech.sri.com radio: n6uok and 7l1fqe ------------------------------ End of Ham-Homebrew Digest V93 #89 ****************************** ******************************