In article , starman
wrote:

I'll start counting vias on my R8B when I can't get to sleep. :-)
Seriously, I'm going to experiment with removing some of the PC board
ground screws to see what happens to certain 'birdies' that I have
identified.

snip

I own an R8B, as you know. Looking around inside it looks to me that
the main problem is no isolation between the digital and analog RF
portions of the harnessing to the front panel. The wires are all
talking to each other in that area of the radio. The analog / RF
controls are fewer than the digital so I would focus on those using
either electrical shielding or maybe common mode choke would be a
better approach. The electrical shield would most likely have to be
grounded on both ends to work well. You could try choking the analog /
RF cables since they mostly carry DC control voltages near the RF
board.

I noticed a few kluges in the radio in the way of not connecting the
coax shield at one end between different boards in the radio in what
looks like the main RF board and synthesizer board. The designer must
have been trying to keep noise from the synthesizer board ground from
getting onto the RF board ground. A transformer would have been a
better approach than leaving the ground dangling at one end. The untied
shield is still in proximity of the RF board components due the shield
ending just before the connector and it will radiate to that point of
course. You could try choking this coax cable around half its length of
the before it gets nears the RF board.

To get a feel of what is happening you can tune the radio to a birdie
and grasp the wiring by the insulation or move the cables around a bit
to see if level changes.

--
Telamon
Ventura, California