LF, Lowe group, Tracey, Alan, Robin,
That receiver is now operating correctly. Thank you very much for your help.
Nothing abnormal was found inside the box, but upon checking the DC supply to
the receiver it turned out to be abnormally low and not too stable. This was
traced to a faulty connector which had four diodes build in as a bridge
rectifier to provide protection against reverse polarity. It appeared that one
or more diodes had gone sour.
Looking at the circuit diagram I see that the HF250 has built-in protection so
the diodes are not necessary. The connector was replaced with one that did not
have diodes in, the voltage presented to the receiver is what it should be, and
the stations I use as a reference (HGA, DCF and France Inter) now all have the
expected readings on the S meter.
Again many thanks.
John F5VLF
On 2 Oct 2011, at 18:55CEST, John Rabson wrote:
> LF,
>
> This receiver has suddenly developed a couple of faults and I would like to
> know if anyone has met something similar.
>
> 1) The only modes in which it produces any audio output are straight AM and
> NFM. Anything requiring a BFO/CIO produces nothing (SSB or synchronous
> AM). Even on theAM setting, turning the volume up to a reasonable level
> produces motorboating.
>
> 2) The S meter readings are noticeably greater than previously.
>
> 3) The remote control no longer works. Yes, I have tried fitting new
> batteries.
>
> John F5VLF
>
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