Date: Wed, 18 May 94 04:30:15 PDT 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 #147 To: Ham-Ant Ham-Ant Digest Wed, 18 May 94 Volume 94 : Issue 147 Today's Topics: ?? Need help with an external short wave radio antenna ?? Baluns and dipoles Ladder Line Marine vhf/uhf antenna Using wood as a beam material (3 msgs) 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, 17 May 94 20:51:15 GMT From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!pipex!sunic!seunet!seunet!sdsmail!hermod@network.ucsd.edu Subject: ?? Need help with an external short wave radio antenna ?? To: ham-ant@ucsd.edu salavi@unity.ncsu.edu (S. Alavi) writes: > I need to gather some info on building an antenna for short > wave reception? Please excuse my ignorance, I am very new at > 1) How long should this wire be? Is it somehow related to the > 2) should the wire be shilded or unshielded? > 3) what should be the gauge of the wire? The thicker the better? > 4) should the wire be the meshed type or a single thread? Stop bothering and start making life simple. Just take whatever wire you have (preferably made of copper) and string it between two of something (a house and a tree, for example). If you dislike the result, put it up between two other things of something. Even better, put up two different wires and test what gives best result. That would give you a good start. When you know the results of all this you may start elaborating on shields, gauge, threads and you name it. ------------------------------ Date: Wed, 18 May 1994 01:05:29 GMT From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!csus.edu!netcom.com!wa2ise@network.ucsd.edu Subject: Baluns and dipoles To: ham-ant@ucsd.edu In article <2r9kov$6pb@search01.news.aol.com> tonyh6@aol.com (TonyH6) writes: >I'm trying to construct dipole antenna for my FM transmitter. A few of the >books I've looked at suggest using a balun transformer between the poles. > >My question. Where do I find one (or how do I make one) and is it really >necessary. > Probably the best way to do a balun is to take the feedline (coax) and wind the antenna end into a coil of around 4 turns about 3 inches diameter. The main purpose of the balun is to keep RF from running down the *outside* of the coax shield. Connect the dipole: one element to the center conductor of the coax, shield to the other element. and the coil an inch or two from this connection. Cheap (like no cost for the balun) and easy. I suppose that the coil forms a transmission transformer or something. ------------------------------ Date: 17 May 1994 21:59:02 -0400 From: newstf01.cr1.aol.com!search01.news.aol.com!not-for-mail@uunet.uu.net Subject: Ladder Line To: ham-ant@ucsd.edu In article <2o5ab6$71o@pace2.cts>, cdsorens@mtu.edu (Christopher D. Sorensen) writes: >>Where does one aquire 450ohm transmission quality ladderline? I have seen in >>included in those over priced dipole kits, but I haven't found it anywhere sold >>sepperatly. Is there a suitable substitute? You can get this ladder line from: The Radio Works (804)-484-0140. They are a mail order firm in Portsmouth, Va ------------------------------ Date: Tue, 17 May 94 19:31:12 MST From: ihnp4.ucsd.edu!swrinde!gatech!newsxfer.itd.umich.edu!nntp.cs.ubc.ca!torn!uunet.ca!uunet.ca!lhaven.UUmh.Ab.Ca!Pj_Butts@network.ucsd.edu Subject: Marine vhf/uhf antenna To: ham-ant@ucsd.edu In a message dated Fri 13 May 94 13:47, Bob Ross wrote: BR> Path: dres.dnd.ca!netfs.dnd.ca!dgbt!nott!torn!howland.reston.ans.net!n BR> oc.near.net!news.delphi.com!usenet BR> From: Bob Ross BR> Newsgroups: rec.radio.amateur.antenna BR> Subject: Marine vhf/uhf antenna BR> Date: Thu, 12 May 94 02:34:37 -0500 BR> Organization: Delphi (info@delphi.com email, 800-695-4005 voice) BR> Lines: 11 BR> Message-ID: BR> NNTP-Posting-Host: bos1d.delphi.com BR> I see hundreds of boats on the water that have 2,3,4,5+ antennas BR> sporting BR> from the cab, deck etc. They all look to be "commercial" (Shakespear BR> etc) BR> antennas. Obviously, the marine band and c.b. band antennas are BR> available BR> but for some reason the comercial "ground-exempt" ham marine BR> comercially BR> made antennas seem to be overlooked. BR> Can anyone ID a comercial antenna maker that makes a GOOD LOOKING BR> 146.00 mhz BR> and or 440 mhz antenna that I can buy for my 19' IO? BR> Thanks......... BR> BOB (N7RBP) Try a line of commercial no ground plane antenna's from Sinclair/Sinclab's. I have put them on boats before for commercial and ham freq.'s and had very good success.They are available for both vhf and uhf freq.Good Luck. -- Via DLG Pro v1.0 Preferred: Pj_Butts@LHaven.UUmh.AB.CA Alternate: Pj.Butts@f3002.n134.z1.fidonet.org ------------------------------ Date: 18 May 1994 00:32:36 GMT From: usc!howland.reston.ans.net!news.cac.psu.edu!news.pop.psu.edu!psuvax1!news.cc.swarthmore.edu!netnews.upenn.edu!msuinfo!harbinger.cc.monash.edu.au!bunyip.cc.uq.oz.au!@@ihnp4.ucsd.edu Subject: Using wood as a beam material To: ham-ant@ucsd.edu I was just looking at some Quagi designs in the ARRL Antenna Handbook, and I was wondering how one would have to modify these antennas if a different beam support material was used (e.g. wood instead of plexiglass or steatite [I think I spelled them correctly]) Are there any general rules of thumb that are used, or is it just a case of "try it and see"? I notice that there is a discussion of modifying designs if a different mounting scheme is chosen for conductive boom material, but I can't seem to find anything relating to non-conductive boom material. Any ideas? Books to look at etc? (someone will probably tell me that this topic *is* covered somewhere in the ARRL Antenna Handbook :-) Tony Gedge. -- | Computer Science Department | tonyg@cs.uq.oz.au (Tony Gedge) | | University of Queensland | -------------------------------- | | St Lucia QLD AUSTRALIA 4072 | "cc stands for Cryptic Crossword" | | FAX: +61 7 365 1999. | PH : +61 7 365 2445 | ------------------------------ Date: Wed, 18 May 1994 03:54:39 GMT From: pa.dec.com!nntpd2.cxo.dec.com!iamu.chi.dec.com!little@decwrl.dec.com Subject: Using wood as a beam material To: ham-ant@ucsd.edu In article <2rbnn4$lus@uqcspe.cs.uq.oz.au>, tonyg@cs.uq.oz.au (Tony Gedge) writes: |>I was just looking at some Quagi designs in the ARRL Antenna Handbook, and |>I was wondering how one would have to modify these antennas if a different |>beam support material was used (e.g. wood instead of plexiglass or |>steatite [I think I spelled them correctly]) Are there any general rules |>of thumb that are used, or is it just a case of "try it and see"? A wood or other non-conductive boom will be invisible (to radio waves) when dry. You might run into a problem if the material gets wet. The ARRL Antenna Book talks about sealing wood with parafin. Fiberglass or plexiglass should be fine replacement for wood, although you probably want to seal the fiberglass with a good exterior varnish or polyurethane to protect it from the weather and keep it dry. Also a good finish would promote beading which would help reduce the effects of surface moisture. 73, Todd N9MWB ------------------------------ Date: 17 May 1994 21:42:10 -0700 From: nntp.crl.com!crl2.crl.com!not-for-mail@decwrl.dec.com Subject: Using wood as a beam material To: ham-ant@ucsd.edu Todd Little (little@iamu.chi.dec.com) wrote: : In article <2rbnn4$lus@uqcspe.cs.uq.oz.au>, tonyg@cs.uq.oz.au (Tony Gedge) writes: : |>I was just looking at some Quagi designs in the ARRL Antenna Handbook, and : |>I was wondering how one would have to modify these antennas if a different : |>beam support material was used (e.g. wood instead of plexiglass or : |>steatite [I think I spelled them correctly]) Are there any general rules : |>of thumb that are used, or is it just a case of "try it and see"? : A wood or other non-conductive boom will be invisible (to radio waves) when dry. : You might run into a problem if the material gets wet. The ARRL Antenna : Book talks about sealing wood with parafin. Fiberglass or plexiglass should : be fine replacement for wood, although you probably want to seal the fiberglass : with a good exterior varnish or polyurethane to protect it from the weather : and keep it dry. Also a good finish would promote beading which would help : reduce the effects of surface moisture. : 73, : Todd : N9MWB I once built a two meter quagi with a 1 X 2 piece of wood for the boom. I drilled holes in the wooden boom for the elements and then glued them in place. After that, I put a couple of coats of polyurethane on it. It was easy to build and worked great. About every two years I had to re-varnish the boom, but that was no big problem. The only problem is that the boom somtimes will warp and twist which makes the beam look strange. It didnt affect the performance. Have fun, Smitty, NA5K -- Henry Smith (hbs@crl.com) ------------------------------ Date: 18 May 94 00:41:23 GMT From: dog.ee.lbl.gov!ihnp4.ucsd.edu!news.cerf.net!ent-img.com!wb6hqk!bart@ucbvax.berkeley.edu To: ham-ant@ucsd.edu References <2qr1ua$hnm@chnews.intel.com>, <2qrn77$cgd@taco.cc.ncsu.edu>, © Subject : Re: A "shorty" 40 M mobile antenna In article , Arva Hudson wrote: >hi >Am interested in 20 meter mobile using a base loaded whip on the middle of the >roof of my Tauras wagon. Probably with a 64 inch whip and 3 inch spring. Do >you think there will be much ground plane component to be effective? > How do you plan on loading it and what is the radiator diameter? Assuming the loading coil is on the radiator somewhere and you aren't intending to tune it with a matchbox through several feet of transmission line, it will work reasonably well, probably better than the same antenna bumper mounted due to the lower ground losses. If you double the radiator length you can expect around a 6 db increase in effective radiated power but not too much better receive performance. bart wb6hqk bart@wb6hqk.ent-img.com ------------------------------ End of Ham-Ant Digest V94 #147 ******************************