K3 SWR tuning indication?

[Jim AB3CV]

I've had a habit of reducing my power to 2W when tuning. I've noticed
for a long time that the SWR indication at minimum when tuning my
remote T1 never went below 1.2:1. No big deal but always made me
wonder what was going on.

A few minutes ago I was playing with the ATU functions again with a
50ohm dummy load and the ATU always made it to 1:1. Yet when I went to
bypass I again got 1.2:1.

Then I remembered that the ATU always tunes at a preset of 5W. I
changed my TUN PWR when in bypass to 5W and got 1:1 after all.

It seems from this that the SWR bridge and its a/d conversion must be
calibrated only at (or above) 5W.

Is that correct?

73

jim ab3cv
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[KK7P]

> It seems from this that the SWR bridge and its a/d conversion must be
> calibrated only at (or above) 5W.

I think it means that with low powers and near matches, the reflected
power is quite low.  To get better resolution on reflected power, you
may need more drive to the bridge.

73,

Lyle KK7P
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