Subject: Re: [QRP-L] Elmer Qustion: Antenna feedline
From: Michael Neverdosky (mikenever@earthlink.net)
Date: Sat Feb 28 2004 - 12:19:27 EST
You can measure the loss of the feedline with your antenna analyzer. I don't have the formulas at hand but they should be online. Look for companion software for the antenna analyzers. Remember that feedline loss makes the SWR look better than it really is. You can put a known resistor at the antenna end (say 200 ohm) and then measure the SWR at the feed end. The lower the SWR, the more loss there is in the cable. If you used a 200 ohm resistor the best would be a measured SWR of 4:1. This would show the lowest loss. If you measure a SWR of 1:1 then the loss is probably WAY high and the coax should be replaced. If you do this measurement on your feedline when new then you can simply compare measurements and see if the coax is failing. This also allows you to measure the loss at the frequencies you use. michael N6CHV Tom Mc wrote: > > Hi gang, > 1) I can easily access the antenna end of the feedline, it is connected to > the Windom by a UHF connector which I can unscrew. > > 2) I have some test equipment including a DMM and a generic version (I > think "Vectronics") of the MFJ antenna analyzer. > Tom McCulloch > WB2QDG
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