Date: Thu, 27 Jan 94 04:30:21 PST From: Ham-Ant Mailing List and Newsgroup Errors-To: Ham-Ant-Errors@UCSD.Edu Reply-To: Ham-Ant@UCSD.Edu Precedence: Bulk Subject: Ham-Ant Digest V94 #15 To: Ham-Ant Ham-Ant Digest Thu, 27 Jan 94 Volume 94 : Issue 15 Today's Topics: Computing antenna coverage HELP on radiation resistance equations Vintage Ham Gear For Sal Where can I find copper-weld?? 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-Ant Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant". 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: Tue, 25 Jan 1994 19:48:24 GMT From: world!cravit@uunet.uu.net Subject: Computing antenna coverage To: ham-ant@ucsd.edu A friend of mine asked me this question, and I do not know the answer. If one has an antenna (say a vertical or something, as opposed to a beam) that is x feet above ground level, how does one compute the approximate coverage area of that antenna (in square miles)? For example, see the following diagram _ | | | | | | | _|_ |x | | | | | | | | Tower | | | | | | | | | ----------------------------------------Ground--------- If we assume that the distance x is, say, 200 feet and that the ground around the antenna is relatively flat, is there a way to estimate the area of coverage for that antenna? Thanks, /MC -- Matthew Cravit, N9VWG | All opinions expressed here are Michigan State University | my own. I don't speak for The World, East Lansing, MI 48825 | and they don't speak for me (luckily E-Mail: cravit@world.std.com | for both of us). ------------------------------ Date: 24 Jan 1994 17:46:58 GMT From: sdd.hp.com!spool.mu.edu!torn!hermes.acs.ryerson.ca!ee.ryerson.ca!jeff@network.ucsd.edu Subject: HELP on radiation resistance equations To: ham-ant@ucsd.edu Wayne Price (wayne@howard.nafb.trw.com) wrote: : HELP NEEDED ON ANTENNA EQUATION FOR RADIATION RESISTANCE! : : Do any of you braniacs know the equation for radiation resistance : of a vertical, shorter than a quarter wave, resonated with a : lossless inductor, over a perfect ground? I can't find the info : in my reference material, but seem to remember that it was an : inverse square relationship. : : For example, if the radiation resistance for a quarter wave is : 36.6 ohms, an eighth wave (resonated with lossless inductor) : would have half the length and one fourth the radiation : resistance, or 36.6/4=9.1 ohms. Likewise, a 3 foot long ten : meter vertical would be about 3/8 of the length and (3/8)^2 =.14 : of the radiation resistance. (.14*36.6=5.1 ohms.) : : Is this correct? Unfortunately, it's not that simple. The entire thing of calculating the radiation resistance of a given antenna at any frequency is depandant on far too many parameters to provide one simple equation for. Having said that, there is an equation for electrically short (<<.1 wavelength) antenna that has a large length to diameter ratio, but I can't seem to find it right now. Your best bet is to find a copy of the ARRL Antenna Handbook. They cover all the 'standard' amateur designs, and give you some insite into why radiation resistance is a little more complicated than one would think. : : Thanks, : Wayne W5GIE (shaking, but not yet breaking) in So. Cal. : : (standard disclaimer applies) 73!!! de Jeff / VE3DJF Internet Jeff@ee.Ryerson.Ca AMPRnet VE3DJF@bbs.VE3RPI.ampr.org AX25 VE3DJF@VE3RPI.#SCON.ON.CAN.NOAM Bill Gates is a bean counter, M$ Windoze cost too much, does to little. This posting sent from a machine running Linux. The UN*X of a GNU generation Get your free copy of the best 32bit operating system from sunsite.unc.edu! ------------------------------ Date: 24 Jan 94 15:23:02 -0600 From: agate!library.ucla.edu!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!ddsw1!chigate!radiohobby!don.merz@network.ucsd.edu Subject: Vintage Ham Gear For Sal To: ham-ant@ucsd.edu Vintage Communications Gear For Sale CONTACT: Don Merz, 47 Hazel Drive, Pittsburgh, PA 15228 412-234-8819 (weekdays, EST) or 412-344-0956 (eves and WEs to 10PM) These are the latest additions to a complete list that is posted in Compuserve HAMNET Library 10 in the file RADIOS.TXT...or available by mail by sending a 2-stamp SASE to the above address. Seeburg jukebox extension speaker. The famous Seeburg teardrop model CV54-8. Pink (or peach?) speckle finish with the word "Seeburg" printed across the grill cloth. Looks and works very good. Should clean up to like-new. $89 Motorola TC-101 UHF TV converter. Some scuffs on original wooden case, but still nice. $13 1957 Eico catalog. As-new: $9 1956 Eico brochure set. As-new: $4 1957 Grommes (Precision) catalog. Large, 3-color. Excellent: $9 1957 Grommes (Precision) catalog. Small, B&W. Excellent: $7 Knight-kit 5 tube AM radio assembly manual. As-new: $4 1971 (?) Panasonic catalog. As-new: $2 1948 Surplus Radio Conversion Manual, Volume I. By Evenson & Beach. Published by techno-graphic publications. Excellent condition. This volume is getting mighty tough to find. $29 CQ MAGAZINE: 1945 issues: July, August, September (2): $7 each CQ-DX Annual. 1948. 1st Edition, 1st Printing. $23 ANTIQUE TV SERVICE LITERATURE: 110 pounds of antique TV service docs including 6 volumes of Riders TV Manuals, service guides from RCA, Dumont, GE and Philco. Hundreds of issues of Circuit Digest and MUCH MORE! Take it all shipped to your door for $75 (includes shipping). SAMS PHOTOFACTS: Over 150 complete photofacts and over 100 partial sets-- fills a four-drawer file cabinet. Numbers range from 100 up through about 450. Take them all for $109 shipped to your door (price includes shipping). Hallicrafters HT-18 transmitter. Missing a knob. Otherwise very nice. $69 National HFS receiver. 1949-vintage plug-in coil set covering 27 - 250mhz. AM/FM (slope-detection)/CW superregen set. With all coils, matching 5886 doghouse power supply and original manual. Front panel is very good, but the paint is smudged and scruffy in many places. Has several scratches on top too. Works perfectly. $169 Multi-Elmac PMR-7 receiver. 160-10 meters. Mobile. 1957-vintage. BRAND NEW IN THE ORIGINAL BOX. Never installed. Has not had power applied since it left the factory. Mint. $279. Multi-Elmac PSR-612 power supply for PMR-7 and other Elmac radios. This is the mobile supply that works on 6 or 12 volts. BRAND NEW IN THE ORIGINAL BOX. Mint. $99. Gonset GSB-100 transmitter. 100 watt, 80-10 meter transmitter with AM, CW and SSB capability. Near-mint in every respect. No scratches, no wear--a real beauty. Works perfectly. Original manual. $239 Abbott TR-4. In two years of combing the market, I have seen exactly one of these ever offered for sale. The Abbott radios were early VHF transcievers covering the old VHF bands: 5 meters and 2-1/4 meters. When the war broke out, they were picked up by the WERS--War Emergency Radio Service--as the civil defense radio of choice. I have two of these, one slightly different from the other. Both show some signs of wear and have not been tested. No manuals. As-is. $149 each. Military TCS transmitter. Slightly modified but nothing shows. As-is. Untested. No manual. $89 Military FRR-21 VLF receiver. This is the shore-based version of the SRR-11. It looks and works like the SRR-11 radio too. Matches the FRR-22 and FRR-23 sets which together cover the HF band. The left handle on this one is slightly bent, though hardly noticable. Neat rarity for the military enthusiast. $179 Meissner 150B Transmitter. 1941-vintage, 150 watt, plate-modulated AM transmitter originally designed for broadcast AM radio station use but drafted by the Signal Corps for the duration. CW too. Covers 1500khz through 12mhz. Uses Meissner Signal Shifter VFO and plug-in coils. This one includes two Signal Shifters, one complete set of coils and a few extras and a manual photocopy. Formerly owned by the Chief Engineer of W1AW, the transmitter has been modified for improved audio. It has several unoriginal 3/8" holes in the 1/8" thick steel front panel. It measures 40"w x 18"h x 20"d and weighs just over 250 pounds. It is not modular and could only be shipped at great expense. Best offer over $900. Multi-Elmac Gear. Classic AM mobile and fixed station equipment from the 50's using a 6146 final to develop 30 watts output. This is all used and cosmetically good, but not excellent. Manuals included. No Mods. Was working when pulled from estate 9 months ago, but untested since. As-is. AF67 Transmitter: $129 (2 to sell) PMR6A Receiver: $99, another one w/cracked plastic dial: $89 PSR6 DC Power Supply: $89 M1070 AC/DC Power Supply (also works with AF68): $139 E. F. Johnson Invader 2000. 1 KW output SSB and CW, 300 watts AM (balanced modulation--not plate modulated). A full gallon in style! When was the last time you saw one offered for sale? Excellent cosmetic and working condition with manual. $1,199 ARRL Hints & Kinks, Volume 2, 1937. No Covers: $4 ARRL Hints & Kinks, Volume 2, 1937. Very good with both covers: $18 Hammarlund HQ-110 receiver. Electrically modified, but nothing shows. Paint is scruffy at the edges, but front panel is excellent and the radio looks good overall. Complete, unworking, as-is: $45 ___ X SLMR 2.1a X ------------------------------ Date: 24 Jan 1994 17:55:21 GMT From: noc.near.net!sunfish.hi.com!brainiac.hi.com!user@uunet.uu.net Subject: Where can I find copper-weld?? To: ham-ant@ucsd.edu In article , pea@wri.com (Bruce Pea) wrote: > I've checked with all the hardware stores and electrical supply > houses in my area and nobody has the stuff. Am I looking in the > wrong places??? Ocean State Electronics P.O. Box 1458 Westerly RI 02891 (800)-866-6626 (orders) (401)-596-3080 (401)-596-3590 (FAX) Universal Radio 6830 Americana Pkwy Reynoldsburg, Ohio 43068 1-800-431-3939 (orders) 1-614-866-4267 (info) Steve Byan internet: steve@hicomb.hi.com Hitachi Computer Products (America), Inc. 1601 Trapelo Road phone: (617) 890-0444 Waltham, MA 02154 FAX: (617) 890-4998 ------------------------------ End of Ham-Ant Digest V94 #15 ****************************** ******************************