I bought a used 77DX with problems. The major one was the chain drive on
the band switches. On some bands the plate switch indexed properly while
the input switch was only partially indexed. On some bands it worked, on
others the input switch was between contacts. I had to loosen the
sprockets and reposition them to get it working.
If you have not tried getting to the sprockets and idler gear, the
front panel lays out when the 6 panel to cabinet screws are removed.
This is a great mechanical design for access.(Note the knob settings
when you fold out the front panel and don't turn the knobs). The amp
also had a cracked reed switch on the input which made contact
intermittently. It was replaced. good Luck, Dan, N5AR
William Fuqua wrote:
>
> You may get a shallow dip if the plate is tuning a harmonic instead of the
> fundamental.
>
> This may be a bandswitch problem. Or something really messed up in
> the output ckt.
>
> 73
> Bill wa4lav
>
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