Date: Sun, 7 Aug 94 04:30:09 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 #250 To: Ham-Ant Ham-Ant Digest Sun, 7 Aug 94 Volume 94 : Issue 250 Today's Topics: ??? Butternut Stub bob-tail curtain Ham-Ant Digest V94 #249 -Reply JPole fundamentals (2 msgs) M-Square HF Log for Sale Question on FM broadcasts... (3 msgs) RG58 versus Thin Ethernet (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: 5 Aug 1994 16:13:25 -0700 From: news.tek.com!cascade.ens.tek.com!not-for-mail@uunet.uu.net Subject: ??? Butternut Stub To: ham-ant@ucsd.edu In article <31rf8f$607@insosf1.infonet.net> darkon@ins.infonet.net writes: >I recently purchased a Butternut HF6-V used. >The only part missing is the 75ohm matching stub. >Does anyone know what the length of it is??? > >Any info helpful... > DARKON@ins.infonet.net Perhaps someone with the right antenna book or a little more up on stubs can help you out with the length. I do know the stub is for 20 meters because the HF6V is 3/8 wavelength long and requires the stub to give you the correct impedance transformation. As I understand it is virtually invisable to the other bands. I used to be more up on how this worked but it's been along time since doing smith charts in college. Terry, KI7M ------------------------------ Date: 6 Aug 94 15:18:40 GMT From: news-mail-gateway@ucsd.edu Subject: bob-tail curtain To: ham-ant@ucsd.edu Could someone lead me to information on the bob-tail curtain or half bob-tail. Thanks -- 73 =========================================================== Robert Wood WB5CRG w5robert@blkbox.com (blkbox is NOT blackbox, inc.!) w5robert@blkbox.com@menudo.uh.edu ============================================================ ------------------------------ Date: 6 Aug 94 13:34:29 GMT From: news-mail-gateway@ucsd.edu Subject: Ham-Ant Digest V94 #249 -Reply To: ham-ant@ucsd.edu I'm on vacation until August 22. I'll read your message and reply when I return. If you need assistance with Emission Monitoring or Stack Testing, please contact Jerry Keefe or Jack Harvanek. Thanks Alan Hicks ------------------------------ Date: Fri, 5 Aug 1994 21:29:32 GMT From: ihnp4.ucsd.edu!agate!biosci!netnews.synoptics.com!news@network.ucsd.edu Subject: JPole fundamentals To: ham-ant@ucsd.edu In article AsE@icon.rose.hp.com, greg@core.rose.hp.com (Greg Dolkas) writes: >Alan Eldridge (alan.eldridge@dragonbbs.com) wrote: > >: Next, I'm going to start working on the Zepp antennas. > >Think about this a minute. That's what a J-pole is. > >Greg KD6KGW Actually, I thought a J looked electrically like: (questionable ascii graphics) ______________________ |______ One continuous electrical (D.C.) short :>) And a Zep like this: 1/4 wave ______ _________________________ and fed as shown. At least this is the description I heard of the Zep as was trailed behind a Zepplin. A good choice since no ground plane is required. I guess the J's matching section resembles the Zeps configuration and it gets lumped in with Zeps. J's and Zeps, two different kinds of antennas? Am I wrong? Dave wa6qwl ------------------------------ Date: 5 Aug 1994 23:39:09 GMT From: ihnp4.ucsd.edu!pacbell.com!UB.com!tandem!barrnet.net!agate!kennish@network.ucsd.edu Subject: JPole fundamentals To: ham-ant@ucsd.edu In article , David Bashaw wrote: >Actually, I thought a J looked electrically like: > ______________________ > |______ >One continuous electrical (D.C.) short :>) >And a Zep like this: > 1/4 wave > ______ > _________________________ > > >J's and Zeps, two different kinds of antennas? Am I wrong? They are really the same thing. The ends of a 1/2 wave end-fed antenna are at a high impedance. Going back a 1/4 wave on the transmission line makes it look like a short. So putting a short there really doesn't make a difference. Or perhaps more clearly, a shorted 1/4 wave stub looks like an open at the other (unshorted) end, so it won't affect the operation of the 1/2 wave section. Where you attach the coax determines your feedpoint impedance. ==Ken ------------------------------ Date: 5 Aug 1994 15:37:25 -0400 From: news1.digex.net!access1!ericr@uunet.uu.net Subject: M-Square HF Log for Sale To: ham-ant@ucsd.edu M-Square 6-10LP log periodic antenna for sale. 6-10 Mhz, single feed, 5 elements. Boom = 34 feet Elements = 54 feet each Weight = approx 100 lbs. This antenna is new and in the box (i.e., never built). Shipping is not included -- FOB Arlington, VA. Asking price = $1000 Contact Eric Rosenberg, WD3Q ericr@access.digex.com or ericr@vita.org ------------------------------ Date: Fri, 5 Aug 1994 22:44:56 GMT From: world!hrick@uunet.uu.net Subject: Question on FM broadcasts... To: ham-ant@ucsd.edu In article , Jeffrey A. Dilcher wrote: >On an FM broadcast, would one channel be transmitted on, say 92.1, and >the other channel on, say, 92.2? No, both channels are on essentially the same frequency. The mono signal (L+R) is on the main freq, say 92.1. The stereo info (L minus R) is on a subcarrier that rides piggyback on the main signal. The subcarrier is amplitude modulated. ------------------------------ Date: Fri, 5 Aug 1994 19:49:44 GMT From: ihnp4.ucsd.edu!dog.ee.lbl.gov!overload.lbl.gov!dancer.ca.sandia.gov!cronkite.nersc.gov!fastrac.llnl.gov!lll-winken.llnl.gov!uop!pacbell.com!amdahl!netcomsv!netcom.com!dilcher@network.ucsd. Subject: Question on FM broadcasts... To: ham-ant@ucsd.edu On an FM broadcast, would one channel be transmitted on, say 92.1, and the other channel on, say, 92.2? I have a digital FM tuner that only has the "odd" frequencies, so I am also wondering whether I would receive a broadcast on an "even" frequency... Thanks for answering a very novice question, Jeff ------------------------------ Date: Sat, 6 Aug 1994 15:31:45 GMT From: ihnp4.ucsd.edu!news.cerf.net!gopher.sdsc.edu!nic-nac.CSU.net!charnel.ecst.csuchico.edu!yeshua.marcam.com!zip.eecs.umich.edu!newsxfer.itd.umich.edu!gatech!wa4mei!ke4zv!gary@network.ucsd. Subject: Question on FM broadcasts... To: ham-ant@ucsd.edu In article dilcher@netcom.com (Jeffrey A. Dilcher) writes: >On an FM broadcast, would one channel be transmitted on, say 92.1, and >the other channel on, say, 92.2? > >I have a digital FM tuner that only has the "odd" frequencies, so I am >also wondering whether I would receive a broadcast on an "even" frequency... > >Thanks for answering a very novice question, Jeff, FM broadcast channels are on 200 kHz centers, and are always at "odd" frequencies, so there is no channel allocated at 92.2 MHz. The bandplan is setup so that no co-channel stations are located within 150 miles of each other, no first adjacent channel stations are within 75-125 (varies) miles of each other, and third adjacent channel stations require 25 mile spacing. So local stations should all be separated by three channel positions on the dial. 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: 5 Aug 1994 11:24:24 GMT From: ihnp4.ucsd.edu!news.acns.nwu.edu!math.ohio-state.edu!howland.reston.ans.net!agate!doc.ic.ac.uk!uknet!fulcrum!strath-cs!bnr.co.uk!adsb@network.ucsd.edu Subject: RG58 versus Thin Ethernet To: ham-ant@ucsd.edu In article <24992.9408041449@csu.napier.ac.uk>, Alastair "J." Downs wrote: > Cable TX DbW Cable Antenna EIRP(DbW) EIRP(W) > Loss Gain > > RG58 14 -2.45 +3 14.55 28.5 > E/Net 14 -1.69 +3 15.31 34 > >Nope ! The difference between 28.5 watts and 34 will never be >noticed. Agreed. But if someone offered you a mechanism whereby you could reduce your receiver's noise figure by 1.24 dB, I bet you'd sit up and be interested. Every dB of cable loss is a dB onto the noise figure of your receiving setup. The lower the cable loss, the better you receive. Andrew Benham -------------------------------------------------------------------- adsb@bnr.co.uk BNR Europe Ltd, 140 Greenway, Harlow Business Park, Harlow, Essex CM19 5QD +44 279 402372 Fax: +44 279 402029 Home: g8fsl@g8fsl.ampr.org [44.131.181.17] -------------------------------------------------------------------- ------------------------------ Date: Fri, 5 Aug 1994 22:22:43 +0000 From: ihnp4.ucsd.edu!agate!howland.reston.ans.net!pipex!demon!g4poi.demon.co.uk!Dave@network.ucsd.edu Subject: RG58 versus Thin Ethernet To: ham-ant@ucsd.edu In article <24992.9408041449@csu.napier.ac.uk> ee17@csu.napier.ac.uk "Alastair "J." Downs" writes: >Thin Ethernet vs RG 58U [...] Thankyou Alastair. I happen to have a reel of thinnet cable and the need for another antenna for 70cms. I shall give it a try and see how it performs. I wonder if you have any thoughts on how weather proof it is likely to be? -- David Dave@g4poi.demon.co.uk ------------------------------ Date: Fri, 5 Aug 1994 20:52:57 +0000 From: ihnp4.ucsd.edu!pacbell.com!amdahl!news.fujitsu.com!barrnet.net!agate!howland.reston.ans.net!pipex!demon!kirsta.demon.co.uk!John@network.ucsd.edu Subject: RG58 versus Thin Ethernet To: ham-ant@ucsd.edu In article <24992.9408041449@csu.napier.ac.uk> ee17@csu.napier.ac.uk "Alastair "J." Downs" writes: > Thin Ethernet vs RG 58U > > Figures are given in Db's (negative assumed ), frequencies are > in MHz and each cable was fitted with BNC 50 ohm connectors. > > The thin ethernet used was RadioSpares 365-133 equivalent to > Belden 9907, BICC H9590, NEK 06231 , multistrand centre, > overall outer diameter 4.65 mm. > > > Freq 50 145 220 433 1300 > > RG58 1.28 2.45 2.26 5.47 9.8 ^^^^^^^^^^^^^^^ > E/Net 0.91 1.69 3.36 3.52 6.5 ^^^^^^^^^^^^^^ Very interesting stuff, Alastair - thanks for posting it. Don't the underlined figures indicate a mismatch somewhere, giving rise to resonance (swr) and hence frequency dependent effects? 73, John, GM4ANB -- John Morris email: John@kirsta.demon.co.uk AX25: GM4ANB@GB7EDN.#77.GBR.EU Absurdity: A statement or belief manifestly inconsistent with one's own opinion - Ambrose Bierce ------------------------------ Date: Fri, 5 Aug 1994 07:17:54 GMT From: ihnp4.ucsd.edu!munnari.oz.au!yarrina.connect.com.au!harbinger.cc.monash.edu.au!newsserver.trl.OZ.AU!pcm8128.trl.OZ.AU!p.tyers@network.ucsd.edu To: ham-ant@ucsd.edu References <1994Aug4.140146.3237@brtph560.bnr.ca>, , <1994Aug4.171411.9160@brtph560.bnr.ca>.trl Subject : Re: G5RV grounding question In article <1994Aug4.171411.9160@brtph560.bnr.ca> jwittich@b4pph107.bnr.ca (Jeffrey Wittich) writes: >In article , cmwdr01@nt.com (Dave Redfearn) writes: >|> >|> >Is my whole approach wrong? >|> >|> Yep :-) >|> For the most efficient multi-band operation, you should remove the coax, >|> feed the the antenna entirely with ladder line or 1" slotted twinlead, and >use >|> a balanced antenna tuner at the shack end. >output. Thats what I get for cheaping it. BTW, to use twin lead, >would I still leave the balun where it is or remove it with the coax >and end up with a 104 ft dipole fed with twin lead? Jeffrey, my $0.02 worth. Louis Varney G5RV in his original article and a later one recommended feeding the 32' of open wire with 75 ohm coax and NO BALUN. Rember the 32' of open wire (26' twin lead allowing for velocity factor) is an integral part of the G5RV antenna, ideally you use a balanced tuner at its end but otherwise his recommendation was unbalanced feed with 75 ohm coax. 73s P Tyers, Tel. +61-(0)3-2536794 JANET: p.tyers%trl.oz.au@uk.ac.ucl.cs ACSnet: p.tyers@trl.oz UUCP:{uunet,hplabs,ukc}!munnari!trl.oz.au!p.tyers CSnet: p.tyers@trl.oz.au ARPAnet: p.tyers%trl.oz.au@uunet.uu.net HAM: VK3KTS MAIL: Telecom Research Laboratories,P.O. Box 249,Clayton,VICTORIA 3168,AUSTRALIA ------------------------------ Date: 6 Aug 1994 00:33:52 -0400 From: peach!atl1!w4qo@uunet.uu.net To: ham-ant@ucsd.edu References , , <1994Aug3.163819.29347@sol.cs.wmich.edu> Subject : Re: ??Loop or dipole ..BEST?? radams@cs.wmich.edu (Robert Adams) writes: >In article , >James C. Stafford wrote: >>I'd vote for the loop. >Screw the loop! I'll take a folded dipole any day. Well, I might have thought the same thing a few years ago, but my friend Dave Fisher, W0MHS, has made a believer out of me. He wrote an article back in '84 (I think) for QST where he models out some of this stuff. I and a lot of friends started using the loops and they have performed remarkable well. I have not had a switch to compare to dipoles, but during contests they sure can provide good results especially in the 300-600 mile range on 80 and the 500-1000 mile range on 40. ------------------------------ End of Ham-Ant Digest V94 #250 ******************************