I was at a hamfest recently and a seller there was discussing how he uses two equal length runs of the same coax (an LMR type) to halve his losses on a long run to a distant tower some 300 or so feet
Mike, This member of the "TT community" says that, if you parallel connect the two lengths - outer to outer, and centre to centre, at each end - you'll have a 25 Ohm line with _the exact same_ matche
So, neglecting the I/R loss issue.....how does he match for the 26 ohm coax he has created? N0UU _______________________________________________ _______________________________________________ TowerT
Author: Mike Fahmie via TowerTalk <towertalk@contesting.com>
Date: Tue, 20 Dec 2016 17:15:56 +0000 (UTC)
I'm assuming that he is putting the 2 cables in parallel. This will result in a composite cable with a surge impedance of half of the single cable, so two 50 cables in parallel will look like a 25 c
You just increased the amount of failure points in the line a bunch too especially if you add in the xfrms at each end. I get it if you had a bunch of coax laying around maybe...sell it and buy bette
It sounds like it work, at least until you do the math. Each run still has the same dB/ft loss. John KK9A I was at a hamfest recently and a seller there was discussing how he uses two equal length ru
On 12/18/16 9:48 AM, rfman45 wrote: I was at a hamfest recently and a seller there was discussing how he uses two equal length runs of the same coax (an LMR type) to halve his losses on a long run to
Uh, maybe this SELLER wants to sell you TWICE as much coax? 10-4? 73 Rob K5UJ _______________________________________________ _______________________________________________ TowerTalk mailing list T
Author: Patrick Greenlee <patrick_g@windstream.net>
Date: Tue, 20 Dec 2016 20:48:56 -0600
If the problem was melting the coax due to too much transmitted power then multiple parallel coaxes would still be inferior compared to a better single run. Now, let's assume we have 100 watts of RF.
In order for a proper match you will need to put two 50 ohm sections in series in each of the parallel sections, then the impedance should match. Wink, wink.... ______________________________________
So - could this be used to fee a ground mounted vertical? 73 Tom W7WHY _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk
Author: Mike Fahmie via TowerTalk <towertalk@contesting.com>
Date: Wed, 21 Dec 2016 04:10:17 +0000 (UTC)
You'd still need to match the 25 line to your 50 source. From: Tom Osborne <w7why1@gmail.com> To: towertalk@contesting.com Sent: Tuesday, December 20, 2016 8:04 PM Subject: Re: [TowerTalk] Double Coa
Author: "J. Hunt via TowerTalk" <towertalk@contesting.com>
Date: Wed, 21 Dec 2016 04:45:21 +0000 (UTC)
I use Andrews Heliax for all my feedlines, with N connectors - including HF bands. Line loss is negligible. Power handling, minimum 5kW. Thanks, James ki5dq Subject: Re: [TowerTalk] Double Coax Runs
It sounds like it work, at least until you do the math. Each run still has the same dB/ft loss. John KK9A Total system loss is the same as a single coax..and no transformers. coax. Stuff 1 kw into th
Exactly right. The good reason for using parallel runs of coax is when you need transmission line of double or half the Zo of commonly available cable. Two applications I can think of are 1) short le
Perfectly clear. However, would the same math apply if the pair of cables were treated as a shielded balanced line? I could see some applications for that. --Mike, WV2ZOW ____________________________
Perfectly clear. However, would the same math apply if the pair of cables were treated as a shielded balanced line? I could see some applications for that. --Mike, WV2ZOW the 2 x center conductors. B
Is this still manufactured? Belden discontinued it several decades ago. I found a 250 ft spool NOS at the Milwaukee hamfest in the '70s and added to my stash, figuring I would sometime find a use fo