[R-390] deaf below 8MHz (R-390A)

[Larry H]

Andre, OK - good progress, it's all about the process of elimination.

Checking the alignment of the RF deck band switch can be checked a few
different ways.  With power off, meter resistance from pin 6 V207 to pin D
on J208 (see book on band switch alignment).  With power on - check voltage
on pin 6 and rotate the megacycle knob from lowest through 8 mh and watch
the voltage in each band.  Or - remove shield from v207 and wrap some turns
of wire around it and feed to different rx, freq counter, or scope, looking
for 17 mh, while moving MC knob from lowest to 8 mh.  No need to remove the
RF deck, yet.

Regards, Larry

On Mon, May 20, 2019 at 3:45 PM atfu <atfu at gmx.de> wrote:

> Many thanks, Larry, for the swift response. Looking at the signal path,
> it really ought to be a 1st mixer problem. Naturally, as I still have to
> warm up to the radio, I am hesitant to remove the RF-module.  So I
> follow your suggestions in the order of least invasiveness.
>
> 1. I turned the three var caps C283-x in the 1st var IF a couple of
> times to resolve possible contact problems. No effect.
>
> 2. I took a good look at the contacts of the mixer and osc tubes, V202
> and V207. Cleaned everything again. No effect.
>
> 3. Tomorrow I'll look at the Y201 crystal in HR-202. I'll report.
>
> 4. Then S208 will be next on the list. Don't even want to think about
> that yet
>
> Best, A
>
>