[BC] Harris SX-1 Spur Problem

[gRAdy Moates]

    I know of an SX-5 with the same problem. . . in the
same condition. . . we've been working on it regularly. . .

    I'm thinking there's a supersonic oscillation somewhere
_after_ the NRSC filter, either in the audio proc or the xmtr,
and the transmitter is passing it.  That's the next thing
we're checking, anyway. . . it's a half-day just  to drive
there and back, though, so it doesn't get looked at every
day.

     Could be as simple as a dried up cap on a +-15V
rail somewhere. . .

Grady

>I have a Harris SX-1 in my care that has a spur problem.  Modulated spurs 
>at
> plus and minus 50 kHz from the carrier at about 45 dB down from carrier.
> The usual suspects have been checked.  PDM frequency is on at 60 kHz.  PDM
> waveform is fine.  Output of oscillator is spectrally ok.  All mosfets in
> PDM and PA are ok.  All power supply voltages are in spec.  Have looked at
> power supplies with scope to see if any regulators are oscillating. 
> Nothing
> found.  All of the big caps have been replaced.  Anyone have any ideas of
> the cause of such a problem?