I have a power/SWR meter in my amplifier (an Expert 2K-FA), as well as an
off-board Power Master.
Both meters show that the SWR level fluctuates somewhat as the power level
changes - getting higher with more power. for example, the range might
bounce around between 1.2 and 1.4 as I talk on sideband at 1 kW, vs. close
to 1.0 after the auto-tuner in the amp runs (generally with 20 to 50W
input). It seems to behave a little differently on different bands.
Changes at the Power Master appear to be dampened somewhat compared to the
amp's meter, but they are there.
Is this normal? If not, what could cause that kind of thing? A poor
connector or a weak coax segment? My station is fairly close to the tower
and antenna. Could it be related to RFI intrusion?
A TDR sweep using an AIM 4170 shows an impedance bump on the near end of the
coax, perhaps from the Power Master coupler - but nothing else that looked
unusual. A "regular" AIM impedance sweep also looks OK.
If the SWR fluctuations aren't normal, suggestions for chasing them down
would be appreciated. I've thought about putting a dummy load at various
points in the coax run, but it would be a fair bit of work, so I'm hoping
there's a better way.
Regards,
Rick
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