Alinco DX-77e Trouble

[Mudfoot]

I picked up an Alinco DX-77e. It has full output in all modes and bands and audio reports are good. The only thing that I have noticed is an issue on LSB. When I select LSB, it sounds like it loses a little sensitivity and the S meter climbs to 3 S units.

Any thoughts? I might invest in an alignment, or an hour bench time poking around, but not much more than that. I have $150 invested. Shame, it's in near mint condition with just a little scuff on the side case.

 

[n4dxx]

Sounds like a carrier point adjustment ..Or your crystal filter has drifted out of spec..

 

[Mudfoot]

Thanks for your input.

I'm leaning towards having a troubleshooting estimate done. Just got to get motivated to pack it up.

 

[nomadradio]

The frequency of the radio's receive carrier for SSB is supposed to be just outside the passband of the receiver's crystal filter. If the crystal's frequency drifts so that it can now pass through the passband, the receiver treats this as if it were a signal coming from the antenna. This can drive up the S-meter, and exaggerate the bass tones in the receiver audio.

If the LSB 'carrier point' setting proves to be correct, this suggets that the receiver's crystal filter has become "wide", and is not rejecting the receiver's carrier like it should.

Without checking the frequency of the LSB carrier crystal, it's a coin toss as to which failure you're seeing.

73

 

[Mudfoot]

Interesting...I'll pass this on to the repair facility. Clairmont Skyland Radio & TV Services is where I'm sending it.

 

[Mudfoot]

Repair shop called...said 3 pin diodes and 2 switching diodes need replaced, followed with an alignment.