In article
,
Paul wrote:

Just bought an old Mk1 FT-s 290R. All is working well (even the back
light)! but when I switch from USB to LSB the background noise drops
on receive and no output is obtained into a dummy load or any movement
indicated on the rigs own meter?

Paul-

I'm not familiar with the 290R. Sideband selection is often done by
switching between local oscillator crystals. It may be a bad crystal, a
dirty switch, or possibly a problem with a diode switching circuit.

If the USB and LSB crystals happen to be plug-in, you could try swapping
them to see if the problem swaps or stays at the same switch position.

Fred
K4DII