[Elecraft] RF feedback? only when using KXPA100

[Bob McGraw K4TAX]

A comment on tuners. The SWR and associated increased loss remains the same on the feed line regardless of the action of the tuner.    When using a tuner, the load only looks better to the transmitter and the tuner presents added overall loss. 

Reflected power is not totally lost power. Only the loss of the feed-line contributes to lost power. 

Bob, K4TAX


Sent from my iPhone

> On Aug 7, 2017, at 8:19 PM, Edward R Cole <kl7uw at acsalaska.net> wrote:
> 
> Concur on suspecting cables as first step for most problems.  Also suspect the meter that measures the signal/voltage/current/etc. Or other items in the line.
> 
> I ran into a similar issue using an antenna tuner on 2m.  I had just put up a 11-element yagi (not real high but equivalent to the vertical previously used).  I could hardly hear my neighbor on 2m-SSB only 15 miles away.  More interestingly he reported my signal as low...hmm.  I switched back to the vertical and signals in both direction jumped up in strength...double hmm!
> 
> OK the yagi had not been in service for a couple years and I was unable to make any tests before it was put up on another tower.  SWR was close to marginal so I inserted my 2m antenna tuner and that fixed the SWR.  I checked power on each side of the tuner and it was about the same ( a little lower on output).  Soooo I removed the tuner and power indicated went from 110w to 100w but the signal jumped in both directions.  Note to self: "leave this tuner on the dusty shelf".
> 
> The SWR is about 1.8 without and tuner but the 100w amplifier is happy (no fold back) and signal are much better on both ends of the circuit (S0 jumped to S3).  Guess that tuner is very lossy (MFJ-921).  Of course MFJ means "mighty fine junk" <smile>
> 
> 73, Ed - KL7UW
>  http://www.kl7uw.com
> Dubus-NA Business mail:
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