Sounds like a thermal problem, possibly with the 8v regulator. I have a problem with my K3 (S# 4K range). If the rig is cold ~60 F the 8v apparently goes out of regulation evidenced by the display illumination dimming on key down. The rig works normally otherwise. The problem goes away once the FP Temp warms a little - I wrote the number down somewhere but can’t find it now.
Good luck & 73, Brian, K0DTJ > On Oct 10, 2022, at 09:49, Michael Carter <mike.car...@unh.edu> wrote: > > Hi Eric, > > I'm voting with my friend Dave, K1WHS, > for looking first at the voltage regulators. > > The 8 volt regulator supplies the TC4427 > gate driver IC, which in turn provides 7R/7T voltages > separately to the Transmit and Receive switching circuits. > The loss of the 7R/7T voltages would disable the > PIN diode T/R switches and render the radio deaf > and unable to transmit. > > If the 8 volt regulator doesn't collapse after some > time observing its output voltage, I would check > the TC4427 (U11 on the RF Board) to be sure its > outputs are correct (the 7R/7T voltages). The > regulator is likely the first culprit - its '8A' output > pin provides power to a large number of circuits > in the radio. > > 73, > Mike, K8CN > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to huntin...@coastside.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
