sorry-spammers "" wrote:
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?

Not sure I'd really get too worried about it.

Maybe things are different in the UK but there is essentially zero activity on LSB on 2 meters over here in the States -- *everyone* uses upper sideband.

The only thing you need LSB for is working a mode-B satellite transponder.

I think the problem is located in or around the sideband oscillator (Q1013).
It could be the LSB sideband crystal (X01) or the circuitry that switches
the crystals.
First check the "LSB +6.8v" line. If it does not work, it would be the
mode switch. I would not apply any "switch cleaner" before checking this.

When this signal is OK, check if the diode is still ok. I think the most
likely failure is in the crystal X01. That would probably not be worth
the trouble to replace, except if you want satellite operation.