Date: Thu, 25 Nov 93 04:30:35 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 #113 To: Ham-Homebrew Ham-Homebrew Digest Thu, 25 Nov 93 Volume 93 : Issue 113 Today's Topics: 210XL Bearcat Scanner to read 1012Mhz? Amplifier for 1270MHz (3 msgs) How to calibrate a DVM LB1473 chips? (2 msgs) Opto-isolator keying Police BBS schematic for audio T pad? single sideband generation Squelch add on W7EL Optimized QRP: VFO Problem 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: 23 Nov 93 12:39:57 CST From: timbuk.cray.com!hemlock.cray.com!mahogany30!n3022@uunet.uu.net Subject: 210XL Bearcat Scanner to read 1012Mhz? To: ham-homebrew@ucsd.edu I am posting on behalf of my father, a retired news photographer who was out there in the action almost every day. Since retirement, most of the "action" he has experienced has been through shortwave (and scanner) monitoring. He has listened to the local police dept for years on 154Mhz. Now the city hall has purchased 900Mhz equipment and have left him in the dark. Rather than buying a new scanner, my father is wondering if there is a converter that will double the upper-end frequency capability of his 210XL Bearcat Scanner from 512Mhz to 1012Mhz. Has anyone run across one? Thanks for your help, Jim n3022@cray.com ------------------------------ Date: Tue, 23 Nov 1993 07:32:23 GMT From: library.ucla.edu!europa.eng.gtefsd.com!emory!kd4nc!ke4zv!gary@network.ucsd.edu Subject: Amplifier for 1270MHz To: ham-homebrew@ucsd.edu In article <1993Nov22.201609.17703@Csli.Stanford.EDU> paulf@Csli.Stanford.EDU (Paul Flaherty) writes: >wa2sff@cbnewsh.cb.att.com (joseph.e.wilkes) writes: > >>I am getting active on 1270 satellites and I need an amplifier >>to raise the 10 Watts of my rig upto about 100 watts. > >Most folks seem to do pretty well into AO-13 using 10w with medium gain >yagis. If you're going for a better uplink, you might want to consider >some of the newer optimized long boom L - Band yagis. As the the saying >goes, aluminum tends to be cheaper than silicon... I used 20 watts, SSB Electronics transverter mounted at the antenna, into a long Down East loop yagi, 19 db, for a while. It worked, sort of, but the required pointing accuracy is a problem, having the transverter at the antenna is a problem, and getting all the antennas boresighted to the same point in space for uplink and downlink is a pain. It's easier to use a 1.2 GHz antenna with about the same beamwidth as the 70 cm yagi and run a bit more power. About 16 db of antenna gain is about right with a 3 db loss feedline (150 foot run) and a 250 watt amp. Kilowatt hours are even cheaper than aluminum if you aren't operating continously. :-) Gary -- Gary Coffman KE4ZV | Where my job's going, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | I don't know. It might | uunet!rsiatl!ke4zv!gary 534 Shannon Way | wind up in Mexico. | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | -NAFTA Blues | ------------------------------ Date: Tue, 23 Nov 1993 07:52:49 GMT From: library.ucla.edu!europa.eng.gtefsd.com!emory!kd4nc!ke4zv!gary@network.ucsd.edu Subject: Amplifier for 1270MHz To: ham-homebrew@ucsd.edu In article <2639@arrl.org> zlau@arrl.org (Zack Lau) writes: >In rec.radio.amateur.homebrew, gary@ke4zv.atl.ga.us (Gary Coffman) writes: >> >>Or you can take the modern approach and use Wilkinson power combiners >>and a bunch of the 20 watt Mitsubishi solid state bricks. That get's >>expensive fairly fast though, say 12 modules for a 240 watt amp, and >>you need a hefty low voltage supply, and insurance that you always have >>a good termination impedance and lightning protection. > >Anyone actually blow up these devices with a high SWR despite >good heat sinking? At rated power, they are usually designed to >withstand a 20:1 SWR, though this undoubtedly degrades if you are >running them at twice their rated power :-). My concern was whether they would be unconditionally stable into certain reactive loads. I've had UHF bricks oscillate if the 100 ohm resistor in the Wilkinson combiner opens. >Keep in mind that it is pretty easy to mount a solid state amp >at the antennas, while only a real *fanatic* would run a water >cooled tube amplifier at the top of a tower. Thus, you might >factor in the feedline loss to get a more realistic comparision. I don't like to mount expensive solid state amps and their heavy DC supplies up where the lightning plays. It's bad enough to have to climb up and replace preamps. I want an elevator if I have to service power amplifiers and 50 amp DC supplies on the tower. :-) Gary -- Gary Coffman KE4ZV | Where my job's going, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | I don't know. It might | uunet!rsiatl!ke4zv!gary 534 Shannon Way | wind up in Mexico. | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | -NAFTA Blues | ------------------------------ Date: 24 Nov 93 15:04:03 GMT From: ogicse!cs.uoregon.edu!sgiblab!darwin.sura.net!fconvx.ncifcrf.gov!fcs260c!mack@network.ucsd.edu Subject: Amplifier for 1270MHz To: ham-homebrew@ucsd.edu In article <2639@arrl.org> zlau@arrl.org (Zack Lau) writes: >In rec.radio.amateur.homebrew, gary@ke4zv.atl.ga.us (Gary Coffman) writes: >>In article wa2sff@cbnewsh.cb.att.com (joseph.e.wilkes) writes: >>>I am getting active on 1270 satellites and I need an amplifier >>>to raise the 10 Watts of my rig upto about 100 watts. >>>Are there any good articles or kits for 2c39 amplifiers? >>> >>>The one the in arrl handbook needs a small machine shop to >>>build. Does anyone make kits? >> >>Or you can take the modern approach and use Wilkinson power combiners >>and a bunch of the 20 watt Mitsubishi solid state bricks. That get's >>expensive fairly fast though, say 12 modules for a 240 watt amp, and >>you need a hefty low voltage supply, and insurance that you always have >>a good termination impedance and lightning protection. ...And (I think it's Zack who replies) > >Keep in mind that it is pretty easy to mount a solid state amp >at the antennas, while only a real *fanatic* would run a water >cooled tube amplifier at the top of a tower. Thus, you might >factor in the feedline loss to get a more realistic comparision. Zack how do you get 240W of 12 V up a tower? Jo NA3T (sorry thats Joe) Joseph MACK NA3T mack@ncifcrf.gov ------------------------------ Date: Mon, 22 Nov 1993 22:12:56 GMT From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!agate!iat.holonet.net!pubcon.fort-worth.tx@network.ucsd.edu Subject: How to calibrate a DVM To: ham-homebrew@ucsd.edu i wouldnt recomend calibrating a dvm on your own, it wont be as accurate with out using a calibration standard used at a calibration lab. they send their standards to the national bureau of standards for calibration. its really not as easy as it sounds. also, are all your meters reading the same type of voltate? eg is one reading average voltage and another reading rms voltage? this needs to be determined before you even try to calibrate them. hope this helps. 73. wb5kxw ------------------------------ Date: Tue, 23 Nov 1993 20:03:29 GMT From: netcomsv!netcom.com!fmitch@decwrl.dec.com Subject: LB1473 chips? To: ham-homebrew@ucsd.edu hi, mitch, wa4osr here in mobile, alabama... i have a hal cri-200 "dumb" rtty modem which has a very nice x/y tuning display using a led diode matrix... the chips which drive the matrix are labeled LB1473 ... i don't reconginze the manufacturer on the chips... no name, just a logo... anyway, i want to build a stand alone tuning unit to use with some of the more "modern" modems, and would like to duplcate the circuit in the cri-200 ... i have tried to find the lb1473 chips to no avail... no reference or cross-reference has them listed... does anyone know of a source of these chips or a substitute... and, if i find the chips, i desperately need a data sheet on them... many thanks if you can help... mitch, wa4osr -- ------------------------------------------------------------------------------- fmitch@netcom.com Felton "Mitch" Mitchell, WA4OSR in Mobile, Alabama USA 205-342-7259 home, 205-476-4100 work, 205-476-0465 FAX co-sysop for W4IAX bbs running fbb ... sysop for WA4OSR DXCluster in Mobile.. ------------------------------------------------------------------------------ ------------------------------ Date: 24 Nov 93 14:54:48 GMT From: ogicse!uwm.edu!spool.mu.edu!agate!iat.holonet.net!vulcan!gary@network.ucsd.edu Subject: LB1473 chips? To: ham-homebrew@ucsd.edu fmitch@netcom.com (Felton Mitchell) writes: > hi, mitch, wa4osr here in mobile, alabama... > > i have a hal cri-200 "dumb" rtty modem which has a very nice x/y > tuning display using a led diode matrix... the chips which drive > the matrix are labeled LB1473 ... i don't reconginze the manufacturer > on the chips... no name, just a logo... > > anyway, i want to build a stand alone tuning unit to use with some of > the more "modern" modems, and would like to duplcate the circuit in > the cri-200 ... i have tried to find the lb1473 chips to no avail... > no reference or cross-reference has them listed... does anyone know > of a source of these chips or a substitute... and, if i find the > chips, i desperately need a data sheet on them... > > many thanks if you can help... > > mitch, wa4osr > -- > ----------------------------------------------------------------------------- > fmitch@netcom.com > Felton "Mitch" Mitchell, WA4OSR in Mobile, Alabama USA > 205-342-7259 home, 205-476-4100 work, 205-476-0465 FAX > co-sysop for W4IAX bbs running fbb ... sysop for WA4OSR DXCluster in Mobile.. > ----------------------------------------------------------------------------- I've also been thinking of building a solid-state tuning indicator. I am presently using a scope, but it is old (and the only tube device left in the shack). My question is, what is the size of the LED matrix, and where does one obtain a matrix. I assume that, with a matrix, a scope-type indicator can be emulated with a pair of A to D converters. Connecting the output of the converters to the matrix could be another problem, though, since one would need to address both x & y coordinates. I've looked into using an LCD screen, but those seem to be addressed sequentially. For tuning indicators, I'm not sure that they are appropriate. -- Gary Tennyson BellSouth Telecommunications, Inc. Internet: gary@vulcan.com ------------------------------ Date: Mon, 22 Nov 1993 22:20:42 GMT From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!agate!iat.holonet.net!pubcon.fort-worth.tx@network.ucsd.edu Subject: Opto-isolator keying To: ham-homebrew@ucsd.edu an opto isolator is nothing more than that, an led with a photo sensing device across from it. circuitry is still going to be needed to act as a switch when hooked to the output of the optoisolator. unless he can trigger his tranciever with the voltage developed by the photosensor of the optoisolator, which might be done in a grid type keying situation but it would be very unlikely. someone correct me if im mistaken. good luck 73 wb5kxw ------------------------------ Date: Fri, 19 Nov 1993 10:57:12 GMT From: dog.ee.lbl.gov!overload.lbl.gov!agate!apple.com!amd!netcomsv!netcom.com!kevincur@network.ucsd.edu Subject: Police BBS To: ham-homebrew@ucsd.edu : : Large selection of file areas...Crime Prevention Information, Ham Radio, Law Enforcement and General Software. Many Door areas are available-Try them--they are entertaining & Fun!! C.O.P.S BBS is available 24 hours a day, 7-days a week. 8-N-1 supports up to 14.4 baud rate. : Thousands of CD-ROM files on-line!!! Check It Out TODAY! ! ! C.O.P.S. B B S San Jose, CA U.S.A (408) 996-7790 : : Tell them Kevin sent you!! -- ----------------------------------------------------------------------------- Kevin Curry P.O. Box 7083 The night prowler strikes again! Fremont, CA 94537-7083 E-Mail - kevincur@netcom.com Never insult seven men, when all you're packin' is a six gun - Zane Gray ----------------------------------------------------------------------------- ------------------------------ Date: 22 Nov 1993 04:32:05 GMT From: nntp.ucsb.edu!library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!vixen.cso.uiuc.edu!moe.ksu.ksu.edu!cis.ksu.edu!mac@network.ucsd.edu Subject: schematic for audio T pad? To: ham-homebrew@ucsd.edu Can anyone please show me the schematic of a "T pad" for remote- control. I know that a T pad uses at least two variable pots and probably keeps the input impedance relatively constant, but I haven't been able to re-invent the circuit by diddling around. --------/\/\/\/\/\/\-------- ^ input | output --------/\/\/\/\/\/\-------- ^ | --Myron. -- # We preserve our freedoms using four boxes: soap, ballot, jury, and cartridge. # Myron A. Calhoun, PhD EE; Assoc. Professor (913) 539-4448 home # INTERNET: mac@cis.ksu.edu 532-6350 work, 532-7353 fax # UUCP: ...rutgers!depot!mac Packet radio: W0PBV@N0ARY.#NOCAL.CA.USA.NA ------------------------------ Date: 22 Nov 93 16:40:24 EST From: psinntp!arrl.org@uunet.uu.net Subject: single sideband generation To: ham-homebrew@ucsd.edu Maybe big advantage to filtering is that you don't really have to be able to know what is going on--to get better unwanted sideband reject you merely throw more more parts in until you meet spec :-). But, with phasing, in order to improve your design, you have to know where the errors are, which might not be intuitively obvious. Thus, unless you *really* know what you are doing, you can go around in circles improving circuits that work just fine, while the real problem lies untouched. BTW, the errors are typically too small to be measured directly. Zack Lau KH6CP/1 Internet: zlau@arrl.org "Working" on 24 GHz SSB/CW gear Operating Interests: 10 GHz CW/SSB/FM US Mail: c/o ARRL Lab 2 way QRP contacts--700+ stations worked 225 Main Street Station capability: QRP, 1.8 MHz to 10 GHz Newington CT 06111 modes: CW/SSB/FM/packet Phone (if you really have to): 203-666-1541 ------------------------------ Date: Tue, 23 Nov 1993 13:37:44 +0000 From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!pipex!uknet!demon!abacus!dmb@network.ucsd.edu Subject: Squelch add on To: ham-homebrew@ucsd.edu I'm currently building a gen. coverage SW superhet. The basic design is quite simple: RF amp/VFO/mixer/2xIF stages/BFO/prod.detector/detector/AGC/CW filter/AF amp. I'd like to incorporate a squelch control, but don't know how it would work, or where I'd incorporate it into the design. Any references/articles/handbook pointers would be much appreciated. 73 David. -- David Byrne, Abacus Software, London, UK Tel: +44 71 930 4884 Email: dmb@abacus.demon.co.uk Fax: +44 71 839 7445 Here's a koan: If you have ice-cream I will give you some. If you have none, I will take it away from you. (it's an ice-cream koan). ------------------------------ Date: 22 Nov 1993 16:06:35 GMT From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!math.ohio-state.edu!news.acns.nwu.edu!casbah.acns.nwu.edu!rdewan@network.ucsd.edu Subject: W7EL Optimized QRP: VFO Problem To: ham-homebrew@ucsd.edu I am building W7EL's ``Optimized'' QRP rig described in Aug 1980 QST, Nov 1980 QST and the 1993 ARRL Handbook. The VFO output (measured on a scope) is only 0.25V pp whereas it should be about 5v pp. The VFO is a Hartley oscillator with a 2N4416 N-JFET. I modified the design from 40m to 20m by halving the inductance and capacitance in the tuned circuit. The VFO oscillates readily and is quite stable. The range is from 14.0000 to 14.145MHz. My only problem is the amplitude. The one other change I made is that I replaced the 2.7pf series capacitor in the gate with a 2pf one. I figured that with a doubling of frequency, this should be fine. Lastly, I am using an NTE equivalent of the 2N4416. The specs were on the wrapper and they seem to match the specs of 4416. Any suggestions?? I am thinking about increasing the gate series capacitor. If that does not work, then replacing the FET. As a last resort, add a 13db gain block. Rajiv aa9ch r-dewan@nwu.edu ------------------------------ Date: Tue, 23 Nov 1993 07:16:28 GMT From: library.ucla.edu!europa.eng.gtefsd.com!emory!kd4nc!ke4zv!gary@network.ucsd.edu To: ham-homebrew@ucsd.edu References , <1993Nov22.154419.23109@ke4zv.atl.ga.us>, Reply-To : gary@ke4zv.atl.ga.us (Gary Coffman) Subject : Re: Amplifier for 1270MHz In article dfeldman@teal.csn.org (Dave Feldman) writes: > >Are you aware of any kw-class amps available (not surplus; designed for >ham use)? Not for satellite -- interested for weak signal terrestrial... I'm not aware of any commercial kW amps designed for the amateur market in the 1.2 GHz band. You might be able to push a 8890 or 3CX800 to 1.2 GHz in a cavity design, but I wouldn't bet on it being stable. You might be able to do a 9 tube ring amp using the 3CX100A5, but I suspect it would be a nightmare to tame. Six of the German amps combined with Wilkinson combiners might do. Probably the best choice would be a klystrode or klystron amplifier. That would certainly be a special order item. Contact Varian, they have external cavity klystrodes and klystrons that may be suitable. Gary -- Gary Coffman KE4ZV | Where my job's going, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | I don't know. It might | uunet!rsiatl!ke4zv!gary 534 Shannon Way | wind up in Mexico. | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | -NAFTA Blues | ------------------------------ End of Ham-Homebrew Digest V93 #113 ****************************** ******************************