I want to sincerely thank everyone that has chimed in on this, both
on and off list. A bit more background: I have no antennas nearby the
rig. My 15 m antenna is up about 60 ft and is about 80 ft total from
the shack (measured along along the hypotenuse). All of my wiring
exits the tower at the base and goes immediately underground exiting
the slab foundation about 5 ft from the rig.
I checked and do not see the problem on 17 m: it appears only on 15
m. The variation is small (about 5 w from what I can see on my
external tuner power meter) with very occasional large, quick drops
that rise back equally fast. I do not see the variations below about
65 W output. Curiously, my ALC indicator lights only briefly upon key
down and then goes out at full power on 15 m. Also, power output on
15 m is only about 70 W into a dummy load. Output on 10 and 12 m is
about 80 W, 15 m is about 70 W, 17 m is about 90 W, 20 m is 90 W, 30,
40 and 80 m is 92-95 W, and 160 m is about 85 W.
Note that this is not a precision meter: it's simply the power meter
on my Ameritron ATR-15 external tuner. I also see small power meter
fluctuation on the radio when this happens. Station ground is single
point and exits via a conduit through the slab and under the porch,
terminating at an 8 ft ground rod (tied to all other grounds) about 8
ft form the rig.
Carl, N4PY, suggested a full, complete reset. I did a complete reset,
but nothing changed regarding what I'm seeing. It appears to be
limited only to 15 m.
I'm reluctant to blame this on RFI quite yet, given that I see
exactly the same behavior whether I'm going to a dummy load or my
antenna, and regardless of whether I use the internal tuner or an
external tuner. The power output seems a bit low on only 15 m and I
know that it can be adjusted, but as I understand it the adjustment
is for all bands and it cannot be adjusted band by band. Power output
on the other bands seems fine, so I'm reluctant to twiddle that
simply for the sake of 15 m and to the detriment of all the other bands.
None of this additional info is likely to help much, but there it is,
regardless
73,
Kim N5OP
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