After having had my Paragon shelved as "hopeless" for several years, I finally
managed to find someone who had the expertise to locate and correct the faults.
It had three equally disabling problems:
Switching bands and/or transmitting, would leave several of the reed relays in
either a closed or undefined state, resulting in poor reception and leaving the
PA unable to put out power when transmitting. Normally a power off/on cycle
would clear this problem for a while. It turned out to be diode D1 on the HP
filter board (81330) which had blown, leaving enough voltage on the reed relays
after being switched, to sometimes keep them closed when they should open. A
replacement of the diode led to a complete fix of the symptoms - for a while!
Then the problem reappeared :-( It turned out that the diode had blown again,
and that the culprit was too much HF creeping from the LP filter board along
the bundle of white control wires to the HP filterboard. A couple of ferrite
clip-ons reduced the amount of HF drastically and the diode was replaced with a
beefier type - apparently fixing the problem permanently.
I have had a lot of problems with the radio loosing lock, and being unstable.
This turned out to be caused by oscillation in the 10.5V regulator circuit on
the reference oscillator (Board 81336), swinging on 1MHz with a swing of more
than 1V P. to P., a redesign (adding a 15uF Tantalum to the output, and
replacing Q3 with a BD234) of the regulator completely cured this.
Finally one of the VCOs was periodically unstable. a complete resolder solved
this for now, but it is suspected that we'll have clear our the comple circuit,
and rebuild it with new components! (a repair by component replacement is
impossible because of the "goo" (heat-glue) its packed in, and which will have
to be removed mecanically)
Vy 73 de OZ1PIF, Peter
********** OZ1PIF **************
email: oz1pif(no-spam-filler)@get2net.dk
http://hjem.get2net.dk/oz1pif
Ph. +45 4619 3239
Snailmail:
Peter Frenning
Ternevej 23
DK-4130 Viby Sj.
Denmark
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