I finally got around to working on an HQ-160 I picked up a few years ago. It
works well, except the CW/SSB is very weak, and the slot (notch) filter doesn't
work at all.

I expect to check voltages around the 6U8 "linear detector" which I assume is a
product detector, though how it works is a mystery to me, being just a pentode
used as a triode. I know the BFO half of the tube is working, since I can hear
it change pitch with the pitch control on an AM signal.

The slot filter is strictly passive components. I've already played with the
slug in its coil, and the notch depth control. I just finished working with my
HQ-180, so I know how effective this slot filter circuit can be -- and my 160
just has nothing. I hope it isn't an open coil.

TIA for any suggestions -- Mike K. AA1UK

Oscar loves trash, but hates Spam! Delete him to reply to me.