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On 28 Jan 2025, 20:47, at 20:47, "J.D. Barron via groups.io" <jeter.d.barron@...> wrote:
Tommy, Pay careful attention to what I am saying here.
If you key the radio RTTY, AM, FM, CW and you are drawing 20 amps AND
if you key the mike on SSB and you draw just a couple of amps you are
producing RF power.
Your radio is drawing power trying to get the feed back from the
forward power measurement circuit to satisfy the CPU power demand
signal and increasing the drive to the point where the IC current limit
is limiting the drive to limit the current draw to 20 amps.
If the radio in SSB is just drawing a few amps in SSB with no audio
input the current limit is not reached because the PA is just sitting
there at idle current.
You do have something keeping the RF power from getting as far as the
forward power sensing circuit and out of the antenna jack, perhaps a
broken trace, bad relay or a band pass filter out of kilter.
While I think that the transformer could be bad, I suspect that it is
not as they are pretty rugged.
It has been a while since I have had an IC-7000 on my bench, but I have
seen this kind of action from a number of radios and often it has been
in the transmitter bandpass filters and either relay drivers or PIN
diodes defective.
I will take time to revisit the prints for the IC-7000 and see if I?
can offer some suggestions, but if I were you I think that I would
start checking the direct pathways through the circuits after the PA
amplifiers. The output transformer is at least carrying current to the
PA from the 13.8 volts and probably the secondary is doing it's job as
well. There could be some shorted caps (or open for that matter) that
are an issue or perhaps one of the TR relays etc.
Just my opinion, but I have managed to be wrong before and I reserve
that option as well.
JD
KE4MD