Re: Grundig Satellit 650 repaired


Thanks for sharing this information , very interesting!

Greetings,
Knut Otterbeck

"Pete KE9OA" <p.gianako@xxxxxxxxxxx> skrev i melding
news:xbydnfN1ZMGb8VXeRVn-hg@xxxxxxxxxxxxxx
>I picked up this unit about a week ago. It was ok when receiving stations,
>but on interstation noise with the preselector untuned, gain was low. The
>clue to the problem was that with AGC disabled and the RF gain control
>turned all the way up, the radio had higher gain than with the AGC enabled.
> The problem was adjustment of R507. This adjustment had probably drifted
> with component ageing over the years. It appears to set the knee point of
> the AGC. Once adjusted, the radio has the same gain in both AGC and MGC
> modes. I think it is the best of the German / Portugese Grundig models
> that I have seen. Not only does it use dual-gate MOSFETs for all of the
> ranges, but it also uses separate ceramic ladder filters for upper and
> lower sideband reception.
> Somebody must have pulled out all of the stops when they designed this
> receiver.
> The only negative point I noticed was some excess sideband noise from the
> synthesizer. If you tune near a very strong station, you will hear the
> noise floor rise up when you get within a few kHz of the station. Also, on
> 49M in the evening you can hear a higher noise floor.
> One of these days, I will narrowband the PLL's loop filter up a bit. Not a
> bad design...........this one's a keeper!
>
> Pete
>


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Relevant Pages

  • Re: Grundig Satellit 650 repaired
    ... Pete ... >>but on interstation noise with the preselector untuned, gain was low. ... the radio had higher gain than with the AGC ... >> noise floor rise up when you get within a few kHz of the station. ...
    (rec.radio.shortwave)
  • Grundig Satellit 650 repaired
    ... but on interstation noise with the preselector untuned, gain was low. ... the radio had higher gain than with the AGC enabled. ... The only negative point I noticed was some excess sideband noise from the ... If you tune near a very strong station, ...
    (rec.radio.shortwave)
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