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Re: Topband: Dipole/remote tuner

To: topband@contesting.com
Subject: Re: Topband: Dipole/remote tuner
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 15 Nov 2022 01:25:50 -0800
List-post: <mailto:topband@contesting.com>
On 11/14/2022 11:41 PM, Roy Morgan wrote:
Do not spend money on a remote antenna tuner till you understand transmission 
line truth.

Yes, there is much that is misunderstood about transmission lines by those who have chosen not to learn the fundamentals. The ARRL Handbook is a great place to start.

Unless the transmission line for a 160M antenna is VERY long, it makes little sense to go to the trouble of weatherproofing a dedicated autotuner at the antenna, even if the antenna is a terrible match to the line. That's because loss in any decent RG8 is quite low at 2 MHz, and even with a fairly long line, bigger coax is probably a lower cost and much simpler solution.

If you know the complex feedpoint impedance, there are many computer programs and apps that can compute the loss in nearly all popular feedline type. Many analyzers can measure it and output it as a data file for use in those programs. The CD that comes with the ARRL Antenna Book includes N6BV's TLW, which can make that calculation for the data at any single frequency.

73, Jim K9YC
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