I have an R-390(non-A) that recently developed a problem. When I first turn
it on, both audio level and RF level (carrier meter) are weak. DC voltage
at the "regulated" test point (J601) on the side of the AF subchassis is
only about 65 to 80 VDC, with less than 0.005 VAC ripple. After "warming
up" for another 5 to 8 minutes, both audio and carrier levels abruptly jump
to "full strength", and regulated DC is up around its rated 180 VDC.
However, audio is distorted with heavy hum, and there's about 4.5 VAC at the
regulated DC test point. Both the high voltage electrolytic (C101) and
regulated DC filter (C103) capacitors check out within spec. Any other
likely culprits to start checking out?

Thanks!
Ken, WB0OCV