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Re: Topband: fixing beverage

To: topband@contesting.com
Subject: Re: Topband: fixing beverage
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 24 Nov 2015 13:18:59 -0800
List-post: <topband@contesting.com">mailto:topband@contesting.com>
On Mon,11/23/2015 2:06 PM, Mike Waters wrote:
Maybe things have improved lately, but AIM would not be my first choice.

There are multiple ways to do TDR. I like the way that this unit does it -- an inverse FFT of a frequency sweep.

http://sdr-kits.net/VNWA3_Description.html

To expose small perturbations in the feedline or system, make the sweep at VHF/UHF. To see only the more gross defects, sweep from about 50-150 MHz. To understand this, remember that a linear frequency sweep will spend more time in the high octaves than the low ones, so the greatest contribution to the display will be that higher octave, whatever you have chosen.

In the example posed by the question about varmint damage, I'd set it for 200 - 1,000 MHz to see small nicks in the braid, 50 - 150 MHz to see the connectors and splices.

73, Jim K9YC


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