From owner-qrp-l@Lehigh.EDU Thu Jun 18 11:12:50 1998 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id LAA24347 for ; Thu, 18 Jun 1998 11:12:49 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <13225-21014>; Thu, 18 Jun 1998 11:10:57 -0400 Received: from nss4.cc.Lehigh.EDU ([128.180.1.13]) by fidoii.cc.Lehigh.EDU with ESMTP id <12550-72466>; Thu, 18 Jun 1998 11:09:22 -0400 Received: from italy.it.earthlink.net (italy-c.it.earthlink.net [204.250.46.18]) by nss4.cc.Lehigh.EDU (8.8.8/8.8.5) with ESMTP id LAA31830 for ; Thu, 18 Jun 1998 11:09:12 -0400 Received: from davide.logicon.com (1Cust231.tnt19.dfw5.da.uu.net [208.254.186.231]) by italy.it.earthlink.net (8.8.7/8.8.5) with SMTP id IAA17475 for ; Thu, 18 Jun 1998 08:09:11 -0700 (PDT) Received: by localhost with Microsoft MAPI; Thu, 18 Jun 1998 09:11:42 -0600 Message-Id: <01BD9A99.1BCC75A0.ekdave@earthlink.net> Date: Thu, 18 Jun 1998 09:11:40 -0600 Reply-To: ekdave@earthlink.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: David Ek To: "Low Power Amateur Radio Discussion" Subject: Two-band dipole from speaker wire for FD? X-To: "'qrp-l@lehigh.edu'" X-Mailer: Microsoft Internet E-mail/MAPI - 8.0.0.4211 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Hi all - I'm trying to prepare for a Field Day backpacking excursion and need to put together an antenna for 40 and 20m. My original thought was a dipole fed with TV twinlead using a tuner, but I'd really like to eliminate the need to carry a tuner and swr meter in my backpack. The thought struck me that I could feed two parallel dipoles with coax and get a good enough match to not need the atu. Then the thought struck me (I'm getting pretty bloodied by now) that I might be able to use zip cord (speaker wire) for the radiator, cutting each of the two conductors for resonance on the two bands I need but otherwise not separating the two conductors. Has anyone tried that before? Seems like the only difference between this and the parallel dipoles in my back yard (which work nicely) is the distance between the radiators for each band. It would certainly be a simple antenna to put up. Also, with dipoles, am I likely to see a significant difference in SWR with different orientations of the radiators (inverted V vs not, for example)? I want to be able to trim for resonance at home and have some confidence that the swr won't be significantly different (i.e. unacceptable) in the field. BTW, my plan is to journey into the mountains just west of here in Colorado Springs. If there are any other qrp-er's in the area who might like to join the expedition, drop me an email. I'm planning an overnight stay in the area of one of the reservoirs. 72, Dave AB0GO From owner-qrp-l@Lehigh.EDU Thu Jun 18 11:57:34 1998 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id LAA27300 for ; Thu, 18 Jun 1998 11:57:29 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <13044-66840>; Thu, 18 Jun 1998 11:56:51 -0400 Received: from nss4.cc.Lehigh.EDU ([128.180.1.13]) by fidoii.cc.Lehigh.EDU with ESMTP id <12532-21014>; Thu, 18 Jun 1998 11:55:42 -0400 Received: from plato.stic.net (mail.stic.net [204.57.118.5]) by nss4.cc.Lehigh.EDU (8.8.8/8.8.5) with ESMTP id LAA43278 for ; Thu, 18 Jun 1998 11:55:36 -0400 Received: from muenzlerk ([129.111.1.216]) by plato.stic.net (Post.Office MTA v3.1.2 release (PO205-101c) ID# 0-51645U10250L5750S0) with SMTP id AAA90; Thu, 18 Jun 1998 10:55:35 -0500 Message-Id: <19980618155534798.AAA90@muenzlerk> Date: Thu, 18 Jun 1998 10:55:32 -0500 Reply-To: wb5rue@stic.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Kevin Muenzler WB5RUE" To: "Low Power Amateur Radio Discussion" Subject: RE: Two-band dipole from speaker wire for FD? In-Reply-To: <01BD9A99.1BCC75A0.ekdave@earthlink.net> X-To: , "'Low Power Amateur Radio Discussion'" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook 8.5, Build 4.71.2173.0 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO > -----Original Message----- > From: owner-qrp-l@Lehigh.EDU > [mailto:owner-qrp-l@Lehigh.EDU]On Behalf Of > David Ek > Sent: Thursday, June 18, 1998 10:12 AM > To: Low Power Amateur Radio Discussion > Subject: Two-band dipole from speaker wire for FD? > > > Hi all - > > I'm trying to prepare for a Field Day backpacking excursion > and need to put together an antenna for 40 and 20m. My > original thought was a dipole fed with TV twinlead using > a tuner, but I'd really like to eliminate the need > to carry a tuner and swr meter in my backpack. The thought > struck me that I could feed two parallel dipoles with > coax and get a good enough match to not need the atu. > Then the thought struck me (I'm getting pretty bloodied > by now) that I might be able to use zip cord (speaker wire) > for the radiator, cutting each of the two conductors for > resonance on the two bands I need but otherwise not > separating the two conductors. Has anyone tried that > before? Seems like the only difference between this and > the parallel dipoles in my back yard (which work nicely) > is the distance between the radiators for each band. It > would certainly be a simple antenna to put up. My suggestion would be a hybrid of the two designs. You might have trouble getting a 40/20 dipole to match using speaker wire because the two radiators are so close together. Why don't you use the tv twinlead for the radiator? I am doing that using the el-cheapo stuff from Radio Shack and it works fine. > Also, with dipoles, am I likely to see a significant > difference in SWR with different orientations of the > radiators (inverted V vs not, for example)? I want to > be able to trim for resonance at home and have some > confidence that the swr won't be significantly different > (i.e. unacceptable) in the field. You probably won't have to worry about this too much. If the resonant frequencies are far apart it won't matter if one is a dipole and the other is an inverted-v. They will probably interact a bit but you should be able to tune them to a very acceptable match on each band. > > 72, > > Dave AB0GO From owner-qrp-l@Lehigh.EDU Thu Jun 18 12:35:15 1998 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id MAA29012 for ; Thu, 18 Jun 1998 12:35:14 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <13285-72466>; Thu, 18 Jun 1998 12:34:28 -0400 Received: from nss4.cc.Lehigh.EDU ([128.180.1.13]) by fidoii.cc.Lehigh.EDU with ESMTP id <13252-66840>; Thu, 18 Jun 1998 12:32:34 -0400 Received: from postoffice.mcg.net ([206.147.121.2]) by nss4.cc.Lehigh.EDU (8.8.8/8.8.5) with ESMTP id MAA23944 for ; Thu, 18 Jun 1998 12:31:58 -0400 Received: from groucho.ka0gkc.amrp.org (i79.cc202.mcg.net [206.10.202.79]) by postoffice.mcg.net (Post.Office MTA v3.1.2 release (PO205-101c) ID# 0-44975U2500L250S0) with SMTP id AAA171; Thu, 18 Jun 1998 11:34:11 -0500 Message-Id: <023001bd9ad6$8b63e320$a10a5e2c@groucho.ka0gkc.amrp.org> Date: Thu, 18 Jun 1998 11:30:39 -0500 Reply-To: applitech@mcg.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: applitech@mcg.net (Claton Cadmus) To: "Low Power Amateur Radio Discussion" Subject: Re: Two-band dipole from speaker wire for FD? X-To: , "Low Power Amateur Radio Discussion" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.2106.4 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Your idea will work fine. As previously suggested you might use twinlead for the whole thing. I don't think the difference in separation will make much difference but I suspect the insulation on the twin lead is a bit less lossy to RF. Also, you can make the antenna out of a single 60 foot (approx.) piece of wire by cutting opposite conductors about 16 feet in from opposite ends and splitting the twinlead/speaker wire between the two cuts through the center. The outside ends become the feedpoint connections at your antenna center insulator. Hope this Helps ---- 73 de KA0GKC Claton Cadmus cla@mcg.net MNQRP #1 Minnesota QRP'ers we're looking for you! Email me or visit this page http://www.qsl.net/mnqrp From owner-qrp-l@Lehigh.EDU Thu Jun 18 14:06:41 1998 Received: from fidoii.CC.lehigh.EDU (fidoii.CC.lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.8.5/8.8.5) with ESMTP id OAA02743 for ; Thu, 18 Jun 1998 14:06:37 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.Lehigh.EDU with SMTP id <13166-54804>; Thu, 18 Jun 1998 14:06:09 -0400 Received: from nss4.cc.Lehigh.EDU ([128.180.1.13]) by fidoii.cc.Lehigh.EDU with ESMTP id <12575-72466>; Thu, 18 Jun 1998 14:04:53 -0400 Received: from postoffice.mcg.net ([206.147.121.2]) by nss4.cc.Lehigh.EDU (8.8.8/8.8.5) with ESMTP id OAA56512 for ; Thu, 18 Jun 1998 14:04:48 -0400 Received: from groucho.ka0gkc.amrp.org (i109.cc202.mcg.net [206.10.202.109]) by postoffice.mcg.net (Post.Office MTA v3.1.2 release (PO205-101c) ID# 0-44975U2500L250S0) with SMTP id AAA123; Thu, 18 Jun 1998 13:07:05 -0500 Message-Id: <024501bd9ae3$85008760$a10a5e2c@groucho.ka0gkc.amrp.org> Date: Thu, 18 Jun 1998 13:03:36 -0500 Reply-To: applitech@mcg.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: applitech@mcg.net (Claton Cadmus) To: "Low Power Amateur Radio Discussion" Subject: Re: Two-band dipole from speaker wire for FD? X-To: , "Low Power Amateur Radio Discussion" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.2106.4 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Opps, >Also, you can make the antenna out of a single 60 foot (approx.) piece >of wire....... That should have read "50 foot (approx.) piece of wire" ---- 73 de KA0GKC Claton Cadmus cla@mcg.net MNQRP #1 Minnesota QRP'ers we're looking for you! Email me or visit this page http://www.qsl.net/mnqrp