Date: Wed, 1 Dec 93 04:30:11 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 V93 #129 To: Ham-Ant Ham-Ant Digest Wed, 1 Dec 93 Volume 93 : Issue 129 Today's Topics: Automatic Antenna tuners Beverage antenna help needed (2 msgs) Isoloop Antenna Isoloop on Apt Terrace Pinched COAX Tower Guy Anchors Turnstile-Reflector 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: 30 Nov 93 01:06:31 GMT From: ogicse!cs.uoregon.edu!sgiblab!munnari.oz.au!pellew.ntu.edu.au!RARP224_43.NTU.EDU.AU!trecon@network.ucsd.edu Subject: Automatic Antenna tuners To: ham-ant@ucsd.edu I am thinking of purchasing an automatic antenna tuner. Could I have some thoughts/comments on these from anyone who has used one. Also, any recommendations? Trevor ------------------------------ Date: Tue, 30 Nov 1993 12:20:00 GMT From: pipex!sunic!news.funet.fi!news.cs.tut.fi!jps@uunet.uu.net Subject: Beverage antenna help needed To: ham-ant@ucsd.edu In article <30NOV93.00113531.0094@UNBVM1.CSD.UNB.CA> NADO000 writes: >We just installed an 80 meter Beverage antenna in order to see how >quiet and directional reception was going to be. > >It is quiet indeed. About as quiet as a dummy load! This includes >the signals coming in... Occasionally, I am able to copy a signal >loud and clear which on my trap dipole is completely lost in the >shuffle. As a rule however, an S9 +30 signal on my dipole leaves an >audio signal that is nice and quiet but the S meter *does not move >at all!* Is this normal? Yes!. Beverage has gain which is few10 dBd minus than normal halfwave dipole in maximum lobes and in mimimum gain is very much lower. My friend, who is also Dx-listener, has 800m!!! Beverage for MW-band, and he says that it work very succsesfull. The main point is that the B attenuates very much more "local" signals which are coming very "high" angles than "DX"-signals coming low angles. So it's possible that your local signal ( signal must be local/near than few hundred kms if its so strong, i think), attenuates so much. > >To make the transformer, going from 500 to 50 ohms, we soldered a >wire Size #18 or so to the antenna wire (size #14, insulated) and >turned it 50turns on a plastic spool. Directly on top of this we put >10 turns of another wire, soldered to a regular 50ohm coax. > I don't know is 10 turns ok for 50ohms on 80m:s, but if you are doing transformer 1:10 (50=>500), the turns must be 10 and 32. 50 turns make output impedance abt 1300 ohms. >Did we do anything wrong? Maybe you could make transformer using toroid core, maybe it works better, but i'm not sure about that. >Luis Nadeau > >Box 7, Site 4, RR4, Fredericton, NB >CANADA E3B 4X5 >FAX: (506)450-2718; Hamcall: VE1LRN (soon to be VE9LN or VE9LRN) > > -- ** Jukka Salonen OH3NLP * E-mail: jps@cs.tut.fi ***************************** ** Addr: Sorva ************************************************************** ******** 37120 Nokia ********* Too old to Rock and Roll, too young to die.*** ******** Finland ************************************************************ ------------------------------ Date: 30 Nov 93 19:00:13 GMT From: ogicse!emory!rsiatl!ke4zv!gary@network.ucsd.edu Subject: Beverage antenna help needed To: ham-ant@ucsd.edu In article <30NOV93.00113531.0094@UNBVM1.CSD.UNB.CA> NADO000 writes: >We just installed an 80 meter Beverage antenna in order to see how >quiet and directional reception was going to be. Not sure what you mean here. An 80 meter (band) Beverage should be about 800 meters long. An 80 meter (long) Beverage should make an effective 10 meter (band) antenna. >It is quiet indeed. About as quiet as a dummy load! This includes >the signals coming in... Occasionally, I am able to copy a signal >loud and clear which on my trap dipole is completely lost in the >shuffle. As a rule however, an S9 +30 signal on my dipole leaves an >audio signal that is nice and quiet but the S meter *does not move >at all!* Is this normal? The Beverage is a travelling wave antenna. If strongly favors low angle radiation from it's end fire direction. (That's why we use them.) Now most *strong* signals will be local/high angle and will be suppressed considerably from the weaker low angle DX signals. So your results aren't too unexpected. Still, a MF Beverage often has *volts* of signal at it's terminals. >To make the transformer, going from 500 to 50 ohms, we soldered a >wire Size #18 or so to the antenna wire (size #14, insulated) and >turned it 50turns on a plastic spool. Directly on top of this we put >10 turns of another wire, soldered to a regular 50ohm coax. > >Did we do anything wrong? Yes. The impedance ratio of a transformer is proportional to the *square* of the turns ratio. So your coil should have a turns ratio of 3.162:1 for an impedance ratio of 10:1. Also, a rule of thumb is that the reactance of the winding should be 10 times the impedance being transformed. That means your antenna coil should have a reactance of approximately 5,000 ohms at the design frequency, and your coax coupling coil should have a reactance of at least 500 ohms. Ferrite loaded coils will likely be more managable. 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: 29 Nov 1993 17:47:08 -0800 From: nwnexus!tedt@uunet.uu.net Subject: Isoloop Antenna To: ham-ant@ucsd.edu Recently, I posted a message describing my Isoloop 10-30 antenna on my terrace being surrounded by metal. I wanted to know if anyone out there had experience with Isoloops on apartment terraces and how I could improve my reception. Unfortunately, when I logged on I lost the response and could not retrieve it. (How does one retrieve lost messages?) Thanks. Ted, KB7ZQQ ------------------------------ Date: 28 Nov 1993 22:13:20 -0800 From: mvb.saic.com!unogate!news.service.uci.edu!usc!math.ohio-state.edu!news.cyberstore.ca!nwnexus!tedt@network.ucsd.edu Subject: Isoloop on Apt Terrace To: ham-ant@ucsd.edu I have an Isoloop 10-30 antenna on my apartment terrace powering my HF rig. The Isoloop is practically surrounded by metal. Anyone have any suggestions on improving reception? Thanks. Ted ------------------------------ Date: Tue, 30 Nov 1993 15:56:36 GMT From: library.ucla.edu!agate!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!yuma!galen@network.ucsd.edu Subject: Pinched COAX To: ham-ant@ucsd.edu In article <1993Nov29.192052.770@pony.Ingres.COM> kerry@Ingres.COM (Kerry Kurasaki) writes: >Query for those "in the know". > >For a mag mount antenna on the car, the COAX will invariably be pinched >at either the trunk, hatch, or door where it enters the passenger com- >partment. Most of us live with that fact, but has anyone measured >what the effects really are? And are these effects really worth worrying >about? When I run the coax thru a car door or the trunk, I make sure the coax crosses the jamb at an angle of 10-30 degrees, NOT AT A RIGHT ANGLE. This spreads the force on the coax over a greater area and decreases the pinching. I also make sure it won't wick water in thru the door by having my angle in the right direction, this will vary depending on what yer running it thru. Galen, KF0YJ ------------------------------ Date: Mon, 29 Nov 1993 22:36:49 GMT From: pacbell.com!sgiblab!spool.mu.edu!sol.ctr.columbia.edu!jabba.ess.harris.com!mlb.semi.harris.com!controls.ccd.harris.com!drs@network.ucsd.edu Subject: Tower Guy Anchors To: ham-ant@ucsd.edu There has been so much ( very interesting ) discussion since my original post that I have learned a lot - but - I was sort of planning the following: (blast me if you wish) 3 inch diameter (heavy wall) steel pipe of about 8 ft long. I was planning on digging down about 3 feet with a shovel. Then in that hole dig with a post hole digger another 3 feet. Put the pipe in and surround all of it with concrete. Then use one of my screw anchors as a back stay tied to the top of the steel post which should be a couple of feet or so out of the ground. That takes care of two guys (if approved by the majority). My original "problem guy" was one that is a bit close to the tower (probably 25% too close).One suggestion was similar to what I plan for the two guys I just mentioned. What about using (just for the close guy) two guys that are 45 degrees off of the center line of the tower leg? The problem I see is in getting them to pull equally on the tower. I do have torque clamps to clamp around the tower at the guying point. Regarding the shrinking / expansion of guy wires. I always thought that guy wires got tighter in the winter time. Seems to me that I have heard of people up North putting towers up in the Summer time and when Winter came, they actually had guys break because they got tighter. Well Enough, Doug, N4IJ ------------------------------ Date: 30 Nov 93 15:06:21 GMT From: news-mail-gateway@ucsd.edu Subject: Turnstile-Reflector To: ham-ant@ucsd.edu The antenna is described in the satellite experimenters handbook. I will bring mine in tomorrow and send you the info. the views expressed here are the author's C. Harper harper@huntsville.sparta.com or kd4qio@amsat.org KD4QIO SPARTA Inc (205) 837-5282 x1216 voicemail 4901 Corporate Drive (205) 830-0287 FAX Huntsville AL 35805 "we have met the enemy and he is us." w. kelly ------------------------------ Date: 30 Nov 1993 16:20:11 GMT From: organpipe.uug.arizona.edu!helium!hlester@uunet.uu.net To: ham-ant@ucsd.edu References <2d0apf$hlj@hpscit.sc.hp.com>, , e.u Subject : Re: Vertical Tri-Bander In article , Cecil Moore wrote: >short runs. I have a MAX2x4 and the improvement over a 1/4 wavelength >ground plane antenna is almost unbelievable. I hit repeaters 100 miles away. > >73, Cecil, kg7bk@indirect.com > I'm impressed! But I can work repeaters 100 miles away with 5 watts and a 1/4 wave ground plane 13' up..... :) I wonder what I'll be able to do when I put up a REAL antenna! Howard ------------------------------ End of Ham-Ant Digest V93 #129 ****************************** ******************************