I have that problem currently with my HF transceiver: no power output at all in SSB and CW, no matter which band / Frequency, but everything is ok in AM, FM and RTTY... There is also a big difference in current consumptions on TX: only about 4A in (not working) SSB and CW, about 20A in (working) AM, FM and RTTY... Where should I look for the failure?
closed as too broad by Phil Frost - W8II, Ron J. KD2EQS, Kevin Reid AG6YO♦, PearsonArtPhoto May 1 '14 at 18:52
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Ok, sorry for the lack of information (I'm the one who asked the question, but now I've signed up and I'm logged in). My TRX is Icom IC-751 (not the "A" version). The SWR/ALC/Power... meter indicates zero ("0") as soon as I push the PTT in SSB or CW. The mic gain is set to max., the RF out is set at least on 10W everytime. What I've done until now: I've checked and new aligned the PLL, checked some voltages according to the service manual (widely available in internet) on the PLL board, logic board and a few on the main board. Everything seems to be ok, the RX is also very good on all bands, in all modes. I'm not really sure if I really have to measure all the check points from the service manual, or I should limit the troubleshooting to the main board and (maybe) the RF board and that's why I have asked for some tips. I'm not sure if I'm allowed to attach the pdf file of the service manual for the IC-751 here but, as we know, it is easy to find it on the net.