Hi Eric,
I was able to tighten those screws a little, but it made no difference.
Adding ferrites to the control cable near the PS helped slightly,
suggesting that that is the source. The RF is definitely being received
by the antenna, about 100 feet away: its strength depends on the antenna
direction, and it is at least 7 dB weaker with a dummy load.
I have submitted a request to tech support.
73,
Scott K9MA
On 12/17/2019 13:44, Eric Swartz - WA6HHQ, Elecraft wrote:
Hi Scott,
We have seen this in rare cases on a few 1500s. It appears to be
caused by the ground connection between the rear RF INPUT SO-239
flange and the chassis.
Very slightly loosening (not too far!) and then firmly re-tightening
all four screws on this SO-239 connector will insure a good ground
connection between this connector and the rear panel. (There are lock
washers between the nuts and the SO-239 inside.)
If the screws are loosened too far, you may have to remove the bottom
cover of the amp to hold the interior nuts in place while you
re-tighten the four screws. (Make sure the 50V power and control
cables are disconnected when you remove any covers on the amp.)
73,
Eric
/elecraft.com/
On 12/14/2019 1:43 PM, K9MA wrote:
I guess it just shows how little I've been on 10, but I've had the
KPA1500 for over a year now, and I just noticed that when I turn it
on, my noise floor on 10 goes up about 3 dB. (And that's from an
urban noise floor.) It's pretty flat over much of the band, not
typical switching supply noise. Has anyone else experienced this and
found a cure? (Other than using the old amp tube.)
73,
Scott K9MA
--
Scott K9MA
k...@sdellington.us
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