[Amps] High SWR on 15 mtrs for SB220 - Follow-up

[Steve Thompson]

Vic Rosenthal wrote:
> Bill Spickler wrote:
>
>> One last thought was to try a different length of coax
>> between the 940 and the amp.  I was using a 44.5" piece of RG8U.  I
>> added another short coax of the same length (kept the original in
>> series as a test to see if it was bad) and guess what..... SWR 1.3:1,
>> no tuner.  I then tried another jumper, RG8X 60".... SWR 1.2:1.
>
> Although changing the length of a transmission line will change the
> impedance seen by the source, it does not change the SWR on the line.
> It doesn't matter whether the load is an amplifier or an antenna.
>
> Therefore, something else is going on.  Perhaps the 940's SWR
> indicator was misled by a large amount of RF flowing on the shield of
> the coax, RF picked up from the antenna?
Maybe the power sensor is broken, or someone tweaked it without
understanding how to do it, or maybe it just never had decent directivity
(too many like that around the place).

Steve