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Re: [TenTec] Ten Tec 238 coupler and 160 meters

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Ten Tec 238 coupler and 160 meters
From: Carl Moreschi <n4py3@earthlink.net>
Reply-to: n4py3@earthlink.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 09 Nov 2013 17:14:15 -0500
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
That's a new one on me. How could loss be less with high SWR on a short length of coax? It makes no sense.

Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com

On 11/9/2013 5:07 PM, Steve Hunt wrote:
Interestingly, when using *short* lengths of coax the loss can be lower
at high SWR than when it's matched. For example, 10ft of RG213 has a
matched loss at 1.9MHz of 0.03dB; but terminated with 500 Ohms
(SWR=10:1) the loss is only 0.012dB - less than half. For a 2500 Ohm
load (SWR=50:1) the loss is 0.046 - only 50% above the matched case.

It's only true for high impedance loads and short lengths, where only a
small portion of the standing wave pattern exists; but they could be the
conditions in this case.

Steve G3TXQ



On 09/11/2013 21:10, Carl Moreschi wrote:
How much coax did you add? The main idea of open wire line is it is
much less lossy than coax at high SWR's. You therefore want to keep
the coax portion is short as practical. The SWR on the feedline could
be 100 to 1 or even higher.

Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com


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