JD,
Thank you for the insight.? I appreciate the response.
I agree with your comment that there may some kind of fault past the L305 transformer.? I have looked for broken traces in the path through to the ant1 connector.? Finding a faulty relay may be difficult but I think each of the band paths are working since all of the receive bands are working.? But I may not be understanding it correctly.?
I have tried to limit transmit time where the current is high.? I did mention in a previous comment that the modulated supply current is lowest at 160M and highest at 50M.
I look forward to your evaluation of the circuit. ?
Thanks
Tommy KF4RWG
On Tue, Jan 28, 2025 at 3:47?PM J.D. Barron via <jeter.d.barron=
[email protected]> 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
