From owner-qrp-l@Lehigh.EDU Wed Nov 11 10:24:09 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 KAA12224 for ; Wed, 11 Nov 1998 10:24:08 -0500 (EST) Received: from localhost ([127.0.0.1]:2043 "HELO Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with SMTP id <54260-32940>; Wed, 11 Nov 1998 10:21:58 -0500 Received: from nss4.CC.Lehigh.EDU ([128.180.1.13]:4397 "EHLO nss4.cc.Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with ESMTP id <53991-49834>; Wed, 11 Nov 1998 10:15:32 -0500 Received: from ticnet.com (smtp.ticnet.com [209.186.224.11]) by nss4.cc.Lehigh.EDU (8.9.1a/8.9.1) with SMTP id KAA181154 for ; Wed, 11 Nov 1998 10:15:32 -0500 Received: from [208.221.218.59] [208.221.218.59] by ticnet-smtp-gw.com [209.186.224.11] with SMTP (MDaemon.v2.7.SP5i.R) for ; Wed, 11 Nov 1998 09:17:00 -0600 Message-Id: <199811111515.KAA181154@nss4.cc.Lehigh.EDU> Date: Wed, 11 Nov 98 09:16:12 -0500 Reply-To: adams@ticnet.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Chuck Adams To: "Low Power Amateur Radio Discussion" Subject: 300 Ohm Ladder Line X-To: qrp X-Mailer: E-Mail Connection v2.5.03 X-MDaemon-Deliver-To: qrp-l@lehigh.edu X-Return-Path: adams@ticnet.com X-Orcpt: rfc822;qrp-l@fidoii.CC.Lehigh.EDU X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Gang, The question came up and let me answer it. YES. 300 ohm ladder line does exist 1. I use it all the time 2. It is low loss 3. It doesn't cost an arm and a leg 4. It is much easier to route around the property then 450 ohm ladder line that has the solid wire I get mine from TX Towers north of me in Plano. They advertise in QST etc. and they are local to me and I hope we all support our local people. Yes, it may cost a little more than mail order or off the web, but they need the business and we need them. And for someone like TX towers they stay in business since a lot of the locals support them. And they give us all the same good deal. Antenna is an OCF dipole fed at a point that is approximately 30M on the 'hot' side and 10M on the 'gnd' side. Fed as a random wire on the MFJ-941C. Probably 10M of ladder line to feed it and it's only 9M from the ground, so not up high. But it works for me at 950mW. Cheap as you can get and all the room I have for an antenna right now. FYI -- Chuck Adams K5FO adams@ticnet.com CP-60 http://www.ticnet.com/k5fo From owner-qrp-l@Lehigh.EDU Wed Nov 11 11:07:05 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 LAA13398 for ; Wed, 11 Nov 1998 11:06:39 -0500 (EST) Received: from localhost ([127.0.0.1]:1090 "HELO Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with SMTP id <54023-32940>; Wed, 11 Nov 1998 11:03:01 -0500 Received: from nss4.CC.Lehigh.EDU ([128.180.1.13]:3806 "EHLO nss4.cc.Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with ESMTP id <54012-32940>; Wed, 11 Nov 1998 10:58:23 -0500 Received: from hotmail.com (f155.hotmail.com [207.82.251.34]) by nss4.cc.Lehigh.EDU (8.9.1a/8.9.1) with SMTP id KAA38562 for ; Wed, 11 Nov 1998 10:58:22 -0500 Received: (qmail 19616 invoked by uid 0); 11 Nov 1998 15:57:50 -0000 Received: from 208.10.216.144 by www.hotmail.com with HTTP; Wed, 11 Nov 1998 07:57:46 PST Message-Id: <19981111155750.19615.qmail@hotmail.com> Date: Wed, 11 Nov 1998 07:57:46 PST Reply-To: al0a@hotmail.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Greg Breeden" To: "Low Power Amateur Radio Discussion" Subject: Re: 300 Ohm Ladder Line MIME-Version: 1.0 Content-Type: text/plain X-To: qrp-l@lehigh.edu X-Originating-IP: [208.10.216.144] X-Orcpt: rfc822;qrp-l@fidoii.CC.Lehigh.EDU X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Chuck and Gang: Thanks for the post on 300 Ohm Ladder line. Also use it and have for years. I get mine from the Wire Man. I found it worked super with a Horizontal Square loop for 75 meters @ 45 feet. I had this antenna at another QTH. I fed the loop with coax then with 450 ohm line. When I changed to 300 ohm line it presented a convenient match to a Transciever. It had to be connected through the 4/1 balun in my tuner but its SWR was the best at all HF bands than any other Antenna/Feed line arrangment I have ever seen. So, it has its uses. I only wish I still had 4 trees placed in the right place! I now have a 75 meter dipole which I feed with 300 ohm. One question though, are the losses of 300 ohm on a par or better/worse than 450? I have always wondered. Greg Breeden, AL0A West Baden, IN 47469 ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com From owner-qrp-l@Lehigh.EDU Wed Nov 11 13:21:23 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 NAA17980 for ; Wed, 11 Nov 1998 13:21:20 -0500 (EST) Received: from localhost ([127.0.0.1]:4911 "HELO Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with SMTP id <53629-49834>; Wed, 11 Nov 1998 13:09:44 -0500 Received: from nss4.CC.Lehigh.EDU ([128.180.1.13]:1188 "EHLO nss4.cc.Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with ESMTP id <53857-49834>; Wed, 11 Nov 1998 12:24:03 -0500 Received: from edison.chisp.net (IDENT:root@edison.chisp.net [207.174.31.1]) by nss4.cc.Lehigh.EDU (8.9.1a/8.9.1) with ESMTP id MAA97242 for ; Wed, 11 Nov 1998 12:24:03 -0500 Received: from default (sl-2.chisp.net [207.174.31.46]) by edison.chisp.net (8.8.5/8.8.5) with SMTP id KAA30195; Wed, 11 Nov 1998 10:23:34 -0700 Message-Id: <199811111723.KAA30195@edison.chisp.net> Date: Wed, 11 Nov 1998 10:26:04 -0600 Reply-To: mgemm@mtechnologies.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Marshall Emm" To: "Low Power Amateur Radio Discussion" Subject: 300 Ohm Ladder Line-- More! In-Reply-To: <199811111515.KAA181154@nss4.cc.Lehigh.EDU> MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Content-Transfer-Encoding: 7BIT X-To: Chuck Adams , qrp-l@lehigh.edu X-mailer: Pegasus Mail for Win32 (v3.01b) X-Orcpt: rfc822;qrp-l@fidoii.CC.Lehigh.EDU X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Hi, Chuck es gang-- >>4. It is much easier to route around the property then 450 ohm ladder line that has the solid wire<< 5. It has a much smaller profile so there's less wind resistance 6. It weighs less so (with number 5 above) it puts less strain on the connection, especially unsupported ones. 7. 300 Ohms is a better match for some antennas at some frequencies. LB-- wanna chart the differences on a dipole cut for resonance at 7050?? Not sure whether the reasons for using ladder rather than coax have been mentioned in this thread, but a co-ax dipole is (with few exceptions) a single band antenna, but feeding it with ladder line preserves the half-wave dipole characteristics on the band it's designed for AND adds multiband capability by turning it into a more generic "doublet." 300 Ohm ladder line is also avaiable from the Wireman, http://thewireman.com/wireline.html and I wrote up the process of replacing a 40M coax fed dipole with a new 300 Ohm ladder line fed one, with pix, in "This Old Dipole" or "Dipole 101," a CQC construction workshop, which you'll find at http://www.morsex.com/dipole/index.htm. 73 Marshall Emm N1FN/VK5FN n1fn@MorseX.com Morse Express "Everything for the Morse Enthusiast" http://www.MorseX.com (303)752-3382 -- From owner-qrp-l@Lehigh.EDU Wed Nov 11 16:27:21 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 QAA24600 for ; Wed, 11 Nov 1998 16:27:20 -0500 (EST) Received: from localhost ([127.0.0.1]:3135 "HELO Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with SMTP id <53547-17832>; Wed, 11 Nov 1998 16:22:02 -0500 Received: from nss4.CC.Lehigh.EDU ([128.180.1.13]:1826 "EHLO nss4.cc.Lehigh.EDU" ident: "IDENT-NOT-QUERIED") by fidoii.cc.Lehigh.EDU with ESMTP id <53298-49834>; Wed, 11 Nov 1998 15:30:37 -0500 Received: from postoffice.mcg.net ([206.147.121.2]) by nss4.cc.Lehigh.EDU (8.9.1a/8.9.1) with ESMTP id PAA58694 for ; Wed, 11 Nov 1998 15:30:37 -0500 Received: from groucho (i104.cc202.mcg.net [206.10.202.104]) by postoffice.mcg.net (Post.Office MTA v3.5.2 release 221 ID# 0-56468U2500L250S0V35) with SMTP id net; Wed, 11 Nov 1998 14:32:13 -0600 Message-Id: <012401be0db2$214eba60$a10a5e2c@groucho> Date: Wed, 11 Nov 1998 14:29:27 -0600 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: 300 Ohm Ladder Line-- More! X-To: , "Low Power Amateur Radio Discussion" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 X-Orcpt: rfc822;qrp-l@fidoii.CC.Lehigh.EDU X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Marshall Emm N1FN/VK5FN wrote: >7. 300 Ohms is a better match for some antennas at some >frequencies. LB-- wanna chart the differences on a dipole >cut for resonance at 7050?? As far as a dipole goes 450 or 300 ohm feedline will make no real difference. Also, to model this system you would need to know the feedline lenght. Any results from the modeling would also be in doubt due to surrounding objects like trees, you house, power lines etc. >Not sure whether the reasons for using ladder rather than >coax have been mentioned in this thread, but a co-ax dipole >is (with few exceptions) a single band antenna, but feeding it >with ladder line preserves the half-wave dipole >characteristics on the band it's designed for AND adds >multiband capability by turning it into a more generic >"doublet." This statement is false. The feedline doesn't change the characteristics of the antenna. The only advantage, and it's a good one, that ladder line has over coax is that it has less losses. This means it has less increased losses with increased SWR as well. Coax will work fine as a feedline in multi-band operation if you are willing to except the losses. Even at ten meters with an SWR of 20 to one at the antenna and the input of the feedline matched via an antenna tuner, the coax losses in RG-8 foam for a run of about 30 ft are only about 2 to 2.5 db. This is less than a half of an S-unit, but it's also about 1/3 of your power! 450 or 300 ohm balanced line comes in about .4db loss under the same conditions. One thing you can do to help if you need to use coax, is choose the lenght of the dipole such that it will show a reasonable low SWR at the frequencies you want to use it. OTOH, ladder line is less expensive then coax and really not that much more difficult to use. I use it for my dipole. More important in my opinion is that you maintain system balance. Use a good choke balun or a balance tuner with any balanced antenna system . If you use coax put the choke balun at the feedpoint of the dipole, it's a balance antenna. If you use balanced line like I do, put the choke balun at the transition point between the balanced line and coax. I do this just outside the shack, coax runs out to the balun, balanced line up to the antenna. 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