Date: Thu, 24 Feb 94 04:30:20 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 #44 To: Ham-Ant Ham-Ant Digest Thu, 24 Feb 94 Volume 94 : Issue 44 Today's Topics: 1/2 wave whip? Antenna on roof, which ground? Difference between Cushcraft A147-20T & A144-20T M2 Enterprises SKIP LOG ANTENNA, experiences ? Need 6 meter beam advise RG8 UHF connectors on slightly small cable (2 msgs) Sommer (DJ2UT) antennas, any experience ? 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: 23 Feb 1994 16:18:25 UTC From: quack!quack.kfu.com!nsayer@uunet.uu.net Subject: 1/2 wave whip? To: ham-ant@ucsd.edu I'm using a 1/4 wave whip on 2M at the moment. Because of space restrictions in my application I haven't room for a 5/8 wave. I'm thinking of a 1/2 wave, which would just fit. I know about 1/2 wave dipoles, but what about a 1/2 wave end-fed vertical? 1. Is an end-fed 1/2 wave antenna a resistive load? What is the impedance? 2. What is the gain perpendicular to the whip? 0dBd? My motivation is to do better than the -1.2dBd of the 1/4 wave spike. The answers must be bad, as if they weren't I'd expect to hear more about 1/2 wave whips than I do... Maybe everyone who wants to move up from a 1/4 wave just jumps into a 5/8? Any other ideas for end-fed antennas (whips) that don't send a sizeable amount of power straight up? :-) -- Nick Sayer | N6QQQ @ N0ARY.#NOCAL.CA.USA.NOAM | "I am not a number! I am a free man!" +1 408 249 9630, log in as 'guest' | PGP 2.2 key and geek code via finger | -- Number 6 ------------------------------ Date: 23 Feb 1994 14:23:09 GMT From: elroy.jpl.nasa.gov!usc!howland.reston.ans.net!pipex!zaphod.crihan.fr!jussieu.fr!univ-lyon1.fr!elendir@ames.arpa Subject: Antenna on roof, which ground? To: ham-ant@ucsd.edu asirene@ntuvax.ntu.ac.sg wrote: : Hi, : I have an antenna mounted on the roof of my apartment building. : The roof is itself some 200 feet at least off the ground. The actual : antenna is roughly 7 feet off the roof at the edge. Now, my question is : this, should I consider the antenna to be 207 feet from the ground, or : 7 feet from the ground, or some complex in between figure. This is a : 20 meter resonant dipole we're talking about. What kind of effect will : such a setup have on my radiation pattern. Well, you have a dipole 3 lambdas over ground. The roof does not count, except if it is metallic. (Or maybe if your buiding has internal metallic reinforcements) You cannot really ignore the effects of ground 3 lambdas over it. It will surely creates maxima and minima where none exist in free space. I'll have a look. But still, it surely looks more like a free dipole than the same antenna 10 meters over ground ! 73, Vince (12 weeks and waiting) ------------------------------ Date: Wed, 23 Feb 1994 14:51:41 GMT From: netcomsv!netcom.com!wroth@decwrl.dec.com Subject: Difference between Cushcraft A147-20T & A144-20T To: ham-ant@ucsd.edu Tony C Blake (tony.blake@stpaul.ncr.com) wrote: : Hi Gang, : I am making some final decisions on what VHF equipment to : purchase. My long range plan is to work the satellites, : but for now be content with terrestrial work. For now, : I want to run the Cushcraft A147-20T. However, while looking : over Cushcraft's AOP-1 OSCAR system, I noticed that one of : the 2m antennas is their A144-20T. This antenna appears to : be identical to the A147-20T. : Does anyone know what the difference is between these two : antennas? Will I be able to use the A147-20T for OSCAR work : in the future? I have the 147-20T, and if you use it for H on one feed, and V on the other it works pretty well. I've run them simultaneously (while gritting my teeth) and rx while tx is possible, but you get desense of course. I was initially afraid that I might blow out the front end of the rx, but the 90 degree orientation gives you enough attenuation. As far as satellite work, I agree with the fellow who lost a lot of money going to the klm's. I've never had the 144-20T, but have heard them on ao-13 with my KLM's. People make fun of you if you have the cushcrafts, although just in jest of course. I suggest that you spend a few bucks on the aluminum, and get KLM's if you want to work satellites. Regarding circular polarization, the difference in listening to those who use linear on AO-13 to circular is significant. The folks who use L have an annoying scalloping from the satellite's rotation. For the LEO birds, the cushcraft would be more than enough, but you'll get tired of them for analog work. Digital work on them is a lot of fun, but you'll want to be automated to do that. Good luck, Wayne Roth WA2N / 5. -- wroth@netcom.com ------------------------------ Date: Wed, 23 Feb 1994 01:11:16 GMT From: lysator.liu.se!gerca@uunet.uu.net Subject: M2 Enterprises SKIP LOG ANTENNA, experiences ? To: ham-ant@ucsd.edu I wonder if anyone have any experience of the M2 Enterprises 7-10-30 LP8 SKIP LOG antenna ? I would be grateful for all answers since we are considering this antenna for our university club station. 73 de Gert E B Carlsson / SM5LWC Linkoping University & Institute of Technology, Sweden E-mail: gerca@lysator.liu.se ------------------------------ Date: 23 Feb 1994 18:15:23 GMT From: agate!etch-eshop.Berkeley.EDU!ron@ames.arpa Subject: Need 6 meter beam advise To: ham-ant@ucsd.edu Hi I'm going to get started in the 6 meter band. If my license ever shows up. I'm looking for advise/experience with 5-6 element beams. Anyone care to comment? 73 Ron Viegelahn ron@etcheshop.Berkeley.EDU ------------------------------ Date: Wed, 23 Feb 1994 07:09:17 GMT From: elroy.jpl.nasa.gov!swrinde!gatech!wa4mei.ping.com!ke4zv!gary@ames.arpa Subject: RG8 UHF connectors on slightly small cable To: ham-ant@ucsd.edu In article <2kb0i2$hgb@hopper.acm.org> smithson@ACM.ORG writes: >I've got some thick-ethernet cable I'm planning to use in my shack. I've >been trying to attach PL259's for RG8 to this cable, but it is a little >thinner than RG8 so the shield does not fit snugly inside the connector. >What is the best way to get the connector attached? I do have N connectors >I could put on, but SO239's on my gear. Would adapters hurt? Depending on how much smaller the cable is, you can double the shield back on itself, or just use a heavier tinning coat than usual to make it fit. I'd recomend that you use crimp connectors instead, however. They make a solid mechanical connection to the braid. Proper tooling to install crimp connectors is expensive, but it's a lifetime investment. Note, don't try to use crimp connectors without the proper tooling. You'll just make a mess of the connection. Gary -- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244 | | ------------------------------ Date: Wed, 23 Feb 1994 12:03:34 GMT From: elroy.jpl.nasa.gov!swrinde!cs.utexas.edu!howland.reston.ans.net!darwin.sura.net!perot.mtsu.edu!raider!theporch!jackatak!root@ames.arpa Subject: RG8 UHF connectors on slightly small cable To: ham-ant@ucsd.edu smithson@ACM.ORG writes: > I've got some thick-ethernet cable I'm planning to use in my shack. I've > been trying to attach PL259's for RG8 to this cable, but it is a little > thinner than RG8 so the shield does not fit snugly inside the connector. Unless you get PL-259 type connectors that are designed for the ethernet cable, you will be FAR better off with the "N" connectors and adaptors. > What is the best way to get the connector attached? I do have N connectors > I could put on, but SO239's on my gear. Would adapters hurt? No, adaptors will NOT hurt, especially at HF. I am using "N" connectors (for weatherproofing, not loss ;^) in my mobile installation...heliflex cable just doesn't go well with UHF connectors. The loss through an "N"-UHF adaptor at HF can't be measured by whatever equipment you are likely to find in your shack. Incidently, that cable is ideal for HF, but the high capacitance (double/triple sheilding) makes it not so fine for VHF/UHF. Use the "N" connectors and an adaptor...and don't worry about it. In most applications, I think the "N" is easier to install properly than a UHF connector, even though the performance differences between the two connectors (ASSUMING *PROPER* INSTALLATION) are indistinguishable. I am using the "N" for convenience and ease of proper installation (and the weatherproof factor) in my mobile, because connector loss isn't usually a factor at 75 meters! ;^) 73, Jack, W4PPT/Mobile (75M SSB 2-letter WAS #1657 -- all from the mobile! ;^) +--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+ | Jack GF Hill |Voice: (615) 459-2636 - Ham Call: W4PPT | | P. O. Box 1685 |Modem: (615) 377-5980 - Bicycling and SCUBA Diving | | Brentwood, TN 37024|Fax: (615) 459-0038 - Life Member - ARRL | | root@jackatak.raider.net - "Plus ca change, plus c'est la meme chose" | +--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--*--+ ------------------------------ Date: Wed, 23 Feb 1994 01:15:50 GMT From: lysator.liu.se!gerca@uunet.uu.net Subject: Sommer (DJ2UT) antennas, any experience ? To: ham-ant@ucsd.edu I wonder if anyone have any experience of the Sommer (DJ2UT) antennas, especially the XP807 antenna, since we are considering one of them for our university club station ? I would be grateful for all answers. 73 de Gert E B Carlsson / SM5LWC Linkoping University & Institute of Technology E-mail: gerca@lysator.liu.se ------------------------------ End of Ham-Ant Digest V94 #44 ****************************** ******************************