Date: Wed, 31 Aug 94 04:30:25 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 #259 To: Ham-Homebrew Ham-Homebrew Digest Wed, 31 Aug 94 Volume 94 : Issue 259 Today's Topics: FFTMORSE (was: DSP on a SoundBlaster) FSTV: Modifying a Gemini RABBIT for amateur service? Help for Equivalent Heath SB104A Part More on Receivers that Radiate Portable EME Station -- Questions regenerative sets and selectivity 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: 30 Aug 1994 13:06:12 GMT From: olivea!inews.intel.com!ilx018.iil.intel.com!ilx049.iil.intel.com!dbraun@ames.arpa Subject: FFTMORSE (was: DSP on a SoundBlaster) To: ham-homebrew@ucsd.edu In article <777704714snx@djwhome.demon.co.uk>, david@djwhome.demon.co.uk (David Woolley) writes: |> Unfortunately this is nothing like what was being asked for, which is |> analogue input and output with digital filtering, which you can't do on |> any of the 8 bit SBs in real time. I am planning to try to prove this wrong. The CPU horsepower is not a problem. Of course, you need a fairly fast CPU (e.g. 486). Also, the PC won't be able to do anything else at the same time... Doug Braun (4X/N1OWU) ------------------------------------------------------------------------ Email: dbraun@inside.intel.com Intel Mail: IDC1-41 iNet: 8-435-5069 Long Distance: 011-972-4-655069 Fax: 8-435-5999 Long Distance: 011-972-4-655999 Snail Mail: US: Other: PO Box 311 Intel Israel, Ltd. Mendham, NJ 07945 IDC-42 Matam Scientific Center Haifa, Israel 31015 ------------------------------------------------------------------------ ------------------------------ Date: Tue, 30 Aug 1994 19:39:17 GMT From: ihnp4.ucsd.edu!news.cerf.net!mr.net!idss.nwa.com!csinc!chrise@network.ucsd.edu Subject: FSTV: Modifying a Gemini RABBIT for amateur service? To: ham-homebrew@ucsd.edu In article , Bruce Toback wrote: >In article <33rb58$9kr@dewey.cc.utexas.edu> rcamama@dewey.cc.utexas.edu (Robert Camama) writes: >> >>Just wondering, >> I could swear I heard something over the last two years about >>modifying a Gemini RABBIT VCR-to-TV wireless TX-RX system [or at least the >>TX part] for amateur FSTV service. Has this been done, or at least, is >>it possible? If so, over what bands [I'm not certain what freqs the RABBIT >>works on]? > >The RABBIT works at around 900 MHz and can easily be modified for use on >the 33cm ham band. There was an article in the November or October 1993 >73 magazine that described the modification and a small power amplifier. > Do these Rabbit transmitters use any sort of chip (like, MC1317x perhaps) as the exciter... or are they all discrete ? I'm curious if they would be mod'able for FM modulation and perhaps highspeed FSK. Chris -- Chris Elmquist, N0JCF voice: (612)631-7614 chrise@comtrol.com fax: (612)631-8117 ------------------------------ Date: Tue, 30 Aug 94 14:44:10 CDT From: ihnp4.ucsd.edu!swrinde!gatech!darwin.sura.net!maze.dpo.uab.edu!uabdpo.dpo.uab.edu!NURS036@network.ucsd.edu Subject: Help for Equivalent Heath SB104A Part To: ham-homebrew@ucsd.edu After 4 years in storage after a move, I dug out my old Heath SB104A to set up in my new house. Unfortunately, some bandswitch contacts are only intermittant, and no amount of cleaning has rectified the problem. Does anyone know of an available equivalent for the following (I only have the Heath part # available...): S1A & B: Heath # 63-721: 2-Wafer Rotary Switch S1C & D: Heath # 63-723: Rotary Switch Any hints on a suitable replacement & where to order them would be appreciated! 73, Michael - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Michael T. Weaver, RN Ph.D. U. of Alabama at Birmingham Internet: nurs036@uabdpo.dpo.uab.edu School of Nursing Bitnet : nurs036@uabdpo UAB Station Radio : kg8h ( qrp arci # 8576 ) Birmingham, AL 35294-1210 Phone : (205) 934-6913 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ------------------------------ Date: 30 Aug 94 14:10:17 GMT From: news-mail-gateway@ucsd.edu Subject: More on Receivers that Radiate To: ham-homebrew@ucsd.edu David Newkirk's post in digest #258 prompted this post. I have first hand experience with the receiver radiation problem he described. I work in an all metal building which thankfully does have windows. I have an antenna for FM broadcast near one office with a window. My favorite station is 102.9 but several others' favorite station is 92.1 including the person whose office is below my antenna. Add 10.7 to 92.1 and you get 102.8 which completely wipes out my station. I looked at it with the spectrum analyser and the LO from the guy's boom box is 5 db stronger than the signal I am trying to receive. This should make it obvious why they do not want you to use a portable FM radio in an aircraft where the LO can easily be in the aircraft band. My experience with cheap boom box type radios and small portable radios has been consistent. They make incredibly good transmitters! Ray WD5IFS mack@mails.imed.com ------------------------------ Date: Mon, 29 Aug 1994 20:42:01 GMT From: ihnp4.ucsd.edu!galaxy.ucr.edu!library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!darwin.sura.net!fconvx.ncifcrf.gov!mack@network.ucsd.edu Subject: Portable EME Station -- Questions To: ham-homebrew@ucsd.edu In article btoback@netcom.com (Bruce Toback) writes: > >I hope that one of these will be the correct newsgroup for this >question; advice on redirection is welcome. > >I'm thinking of assembling a portable EME station that I could use >for demonstrations at schools. I don't know if such a thing is >possible at any reasonable cost, or for any reasonable definition >of "portable." But here are the questions anyway: > >1. I assume that because of my Arizona location, I can't use > 432MHz. This seemed to be the best compromise between power > amplifier practicality and antenna size. Is 23cm a good > second choice? I've just started on EME. I picked 2m because there's more gear available, and there are more people on 2m EME than other bands. There are technical reasons (cooler sky) why 432 etc are better, but if you want to get on easily, 2m can't be beat. > >The objective is a station that can hear its own echoes -- not >necessarily with communication-capable quality -- and can >communicate with a "big gun" EME station. A station that can hear its own echoes is a big gun station to me. I think there are a lot more people who can't hear their own echoes than those that can. Joe Mack NA3T mack@ncifcrf.gov (Nat Inst Health) > >Thanks, >-- Bruce Toback >KN6MN ------------------------------ Date: Tue, 30 Aug 1994 18:50:00 GMT From: ihnp4.ucsd.edu!mvb.saic.com!news.alpha.net!MathWorks.Com!news.duke.edu!news-feed-1.peachnet.edu!gatech!swrinde!sdd.hp.com!col.hp.com!srgenprp!alanb@network.ucsd.edu Subject: regenerative sets and selectivity To: ham-homebrew@ucsd.edu Brent G. DeWitt (bdewitt@csn.org) wrote: : Dave Newkirk (WJ1Z) (dnewkirk@arrl.org) wrote: : : It's good to see that relatively little traffic on this topic has dwelt long : : on the issue of how much a regen or a superregen radiates. (Any text that : : says something like "Don't use those detectors; they radiate" is another : : case of the specific case, or implementation, being taken as the general : : case. An RF-amplifierless "direct-conversion" receiver, and likewise an : : RF-amplifierless superhet with a poorly balanced mixer and insufficient : : input selectivity, will also radiate, sometimes quite strongly.) A : : reasonably unliteral RF amplifier stage, along with proper shielding, can : : take care of detector or mixer radiation in any of these cases. Input : : filtering (in superhets) also helps. : : Data point: The 40-meter regen I published in Sep 1992 *QST* radiates--at a : : level of roughly 12 picowatts into a 50-ohm antenna load. : In general, regens DO radiate! The FCC requires that they be CERTIFIED : with the FCC before commercial sale, while super-hets only require : notification. None of this means a thing as an experimenter building one : item for his/her use, but it does imply that history has shown regens to : be pretty good transmitters...... People generally use regenerative detectors to reduce circuit complexity, which implies that the rest of the circuit should be simple too. For that reason, most regen's lack an RF amplifier in front of the detector, so they radiate like crazy. However, as Dave mentions, it is quite possible to eliminate the problem by including an RF amplifier with good reverse isolation. Another way is to use the regenerative detector at an IF frequency, as part of a superhet receiver: Most mixers have enough isolation to eliminate any radiation problem. AL N1AL ------------------------------ Date: 30 Aug 1994 18:21:11 GMT From: galaxy.ucr.edu!library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!gatech!newsxfer.itd.umich.edu!jobone!fiesta.srl.ford.com!eccdb1.pms.ford.com!rchp33.eld.ford.@ihnp4.ucsd.edu To: ham-homebrew@ucsd.edu References <515@ted.win.net>, <1994Aug29.152234.29324@arrl.org>, Subject : Re: regenerative sets and selectivity Brent G. DeWitt (bdewitt@csn.org) wrote: : Dave Newkirk (WJ1Z) (dnewkirk@arrl.org) wrote: : : It's good to see that relatively little traffic on this topic has dwelt long : : on the issue of how much a regen or a superregen radiates. (Any text that : : says something like "Don't use those detectors; they radiate" is another : : case of the specific case, or implementation, being taken as the general Hear Hear! I cannot agree more. Sure, there are lots of examples of crude superregens that radiate like banshees, but they are just that--crude receivers. Superregens are superior to 'hets in terms of sensitivity vs. cost and simplicity, IMHO. Same sort of baseless statements as: MOSFET's are better than bipolar transistors, RISC is better than CISC, and Coke is better than Pepsi. Of course, the last is a TRUE statement, but I digress..:-) : : case. An RF-amplifierless "direct-conversion" receiver, and likewise an : : RF-amplifierless superhet with a poorly balanced mixer and insufficient : : input selectivity, will also radiate, sometimes quite strongly.) A : : reasonably unliteral RF amplifier stage, along with proper shielding, can : : take care of detector or mixer radiation in any of these cases. Input : : filtering (in superhets) also helps. Very good points indeed. Having direct experience with designing both types of receivers, I completely agree. A superregenerative transistor oscillator usually runs with about 200 uA of collector current, while the LO in most wireless-type superhet designs consumes at least a couple mA. When both circuits are preceeded by a well designed amplifier with a decent amount of reverse isolation, say 40 dB or so, the radiated emissions will meet US FCC, Canadian DOC, and the various european regs. : : Data point: The 40-meter regen I published in Sep 1992 *QST* radiates--at a : : level of roughly 12 picowatts into a 50-ohm antenna load. Another data point, the 315 MHz superregenerative recevier inside the upcoming Explorer's Remote Keyless Entry system is about 3-4 dB off the noise floor at 3 meters. I would consider both my design and David's to be "state of the art" in terms of superregen receivers. : In general, regens DO radiate! The FCC requires that they be CERTIFIED : with the FCC before commercial sale, while super-hets only require : notification. None of this means a thing as an experimenter building one I don't consider that the FCC only requires notification for 'hets to mean that they are superior from a re-radiation standpoint! Remember, the FCC had to mold and shape the broadcast world that we now live in, and their plan was to make the receivers cheap, simple, and easy to market. The rule for Notification for the superhet's simply makes it easy to market, and takes them off of the hook of having to tightly regulate all the mfgr's of broadcast sets. The economics and business reasons for this rule are, IMHO, more significant than any technical reasons. : item for his/her use, but it does imply that history has shown regens to : be pretty good transmitters...... Seeing that history has spent much more effort improving the superhet, as it supports both FM and AM broadcast, that is not that hard to believe. I have a very thorough collection of superregen articles and papers, and they fill about 6" of file cabinet space. I wouldn't even attempt to collect all the papers and patents re: superhets. The reason for the regen's bad rap is that in thermionic times (that's toobs to you and me) an RF stage was an extra capacitor gang, an extra tube, and more W of filament power--real product cost/benefit considerations. Now, mass-produced superregens are relegated to wireless control receviers, a job which they do very well, but ultra cost sensitive -- an RF stage adds components, board space, current draw, etc. -- again, real cost/benefit tradeoffs. As wireless products become more complex, you will see them move away from superregens to other topologies that support more complex & compact modulation methods, but only when costs allow and functionality demands it. But of course, I am biased as I design superregens for a living... I would be happy to correspond with anyone wanting to discuss the merits and pitfalls of this simple, sensitive, and cost effective receiver... -- Tom LeMense RF Product Design Engineer Ford Motor Co - Electronics Division tlemense@rchp33.eld.ford.com '82 XV750 Virago DoD #1074 ------------------------------ Date: 30 Aug 1994 15:37:30 GMT From: ihnp4.ucsd.edu!dog.ee.lbl.gov!overload.lbl.gov!agate!howland.reston.ans.net!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!ssd.intel.com!chnews!scorpion.ch.intel.com!cmoore@@. To: ham-homebrew@ucsd.edu References , <777704714snx@djwhome.demon.co.uk>, <33vas4INN11j4@ilx018.iil.intel.com>ew Subject : Re: FFTMORSE (was: DSP on a SoundBlaster) In article <33vas4INN11j4@ilx018.iil.intel.com>, Braun Doug wrote: >In article <777704714snx@djwhome.demon.co.uk>, david@djwhome.demon.co.uk (David Woolley) writes: > >|> Unfortunately this is nothing like what was being asked for, which is >|> analogue input and output with digital filtering, which you can't do on >|> any of the 8 bit SBs in real time. > >I am planning to try to prove this wrong. The CPU horsepower is not a >problem. Of course, you need a fairly fast CPU (e.g. 486). Also, >the PC won't be able to do anything else at the same time... >Doug Braun (4X/N1OWU) Hi Doug, I don't think David means the PC can't do the filtering. I have been down the same road and found that an 8-bit A/D needs AGC on the front end where a 16-bit A/D does not. Saturation is a huge problem in 8-bit systems and the dynamic scaling required eats up a lot of CPU power. Low dynamic range often leaves one with almost no low-level signal left to filter. It can be done with 8-bits but the complexity is IMO, not worth it. A 16-bit A/D gives one a lot of "headroom" and has saved my sanity. A 2-pole sigma filter gets rid of a lot of noise, too. 73, Cecil, KG7BK, OOTC (Not speaking for Intel) -- Intel, Corp. 5000 W. Chandler Blvd. Chandler, AZ 85226 ------------------------------ Date: (null) From: (null) "This Disc contains Hacking, Phreaking, Tone Box Information, Anarchy, Subculture, Magic, Internet & Computer Security Secrets, Bomb Plans, FBI & Police Net Files, Virus Code, Sick & Twisted Graphics, UFO, Occult, even HAM RADIO Files, plus much, much more!" ^^^ ^^^^^ ------------------------------ Date: Tue, 30 Aug 1994 22:17:28 GMT From: ihnp4.ucsd.edu!swrinde!gatech!newsfeed.pitt.edu!gvls1!rossi@network.ucsd.edu To: ham-homebrew@ucsd.edu References <1994Aug29.152234.29324@arrl.org>, , <33vtan$b0v@eccdb1.pms.ford.com> Subject : Re: regenerative sets and selectivity In article <33vtan$b0v@eccdb1.pms.ford.com> tlemense@rchp33.eld.ford.com (T J LeMense (Tom)) writes: >Brent G. DeWitt (bdewitt@csn.org) wrote: >: Dave Newkirk (WJ1Z) (dnewkirk@arrl.org) wrote: > >: In general, regens DO radiate! The FCC requires that they be CERTIFIED >: with the FCC before commercial sale, while super-hets only require >: notification. None of this means a thing as an experimenter building one > >I don't consider that the FCC only requires notification for 'hets to mean >that they are superior from a re-radiation standpoint! Remember, the FCC >had to mold and shape the broadcast world that we now live in, and their >plan was to make the receivers cheap, simple, and easy to market. The >rule for Notification for the superhet's simply makes it easy to market, >and takes them off of the hook of having to tightly regulate all the mfgr's >of broadcast sets. The economics and business reasons for this rule are, >IMHO, more significant than any technical reasons. > >: item for his/her use, but it does imply that history has shown regens to >: be pretty good transmitters...... Superhets radiate too!! I discovered recently while trying to listen to a repeater on 444.0 MHz I kept hearing various carriers and noises come and go as I drove around. They sounded very "local" since often they were full quieting but they would have lots of very deep fades then disappear a half mile down the road... then come back... then disappear. Turns out what I was hearing was the local oscillators in other car radios tuned to a popular local FM station on 100.3 MHz 100.3 + 10.7 = 111.0 MHz LO frequency x 4th harmonic = 444.0 MHz With some car radios (mine) you can even hear some modulation from the FM station way way way down in the noise. If you have 440 mobile, pick the 440 frequency that matches a local FM station and see how many car radios you can hear while you are driving around ;-) You will be amazed! Some of those suckers really put out some signal! FM STATION LO LO 4th harmonic 99.50 110.20 440.80 99.70 110.40 441.60 99.90 110.60 442.40 100.10 110.80 443.20 100.30 111.00 444.00 100.50 111.20 444.80 100.70 111.40 445.60 100.90 111.60 446.40 101.10 111.80 447.20 101.30 112.00 448.00 101.50 112.20 448.80 101.70 112.40 449.60 ================================================================= Pete Rossi - WA3NNA rossi@vfl.paramax.COM Unisys Corporation - Government Systems Group Valley Forge Engineering Center - Paoli, Pennsylvania ================================================================= ------------------------------ End of Ham-Homebrew Digest V94 #259 ******************************