[R-1051] Synthesizer Questions

[Cecil Acuff]

Hi Jan,

        I always start at the Frequency standard all synthesizer function
depend on it being healthy...use a known good one.  I then check the three
inputs to the Translator from the various synthesizers.  You will find that
the synthesizers are interdependent...with the exception of the 1 MC
synthesizer.    The output of some are dependant on inputs from others...it
gets tricky some times figuring out that the output of one is not there
because the input from another is missing.  I look for the proper
frequencies into the Mixers based on the frequency set on the front panel.
I also look for the proper levels.  That will usually tell all.  Usually one
of those is missing.  I will also do an alignment on the spectrum
generator...stepping through it from beginning to end.  The waveforms and
levels are in the manual.  An alignment problem in the spectrum generator
will cause improper outputs from the synthesizers.

Try it on different frequencies...sometimes a dead crystal in the 1 and 10
kc synthesizer will make it seem as though the radio is dead on all bands
when in fact you are always just sitting on an even 1 or 10 kc setting.

Another problem I have seen several times...the motor that drives the
crystal switch in the 1 MC synthesizer will stall...the brushes and
commutator get gummed up...and the switch is not working leaving you sitting
on one crystal....the results is that the radio only works on one 1 MC
segment...easily overlooked.  It is most easily found by listening as you
change MHZ steps on the front panel...you should hear two motors
running...one to drive the turret assembly in the RF deck and one in the 1
MC synthesizer. (quieter)

Those should get you going...also be sure to set the IF gain through the
Translator...There should be around 10 to 12 db of gain...if set improperly
you will have AGC problems. More is not better!  It works like the
R-390A...if you set the gain lower the set has greater sensitivity...but the
R-1051 doesn't have too much audio power to make up for the reduced gain in
the IF.  I have thought about driving a decent stereo amp with the line outs
and setting the IF gain very low...probably would make the radio much
quieter...

Good Luck..

Cecil...
----- Original Message ----- 
From: <jan at skirrow.org>
To: <r-1051 at mailman.qth.net>
Sent: Sunday, June 08, 2003 2:59 PM
Subject: [R-1051] Synthesizer Questions


> Thanks to the list for the great help on my recent freq std query. I now
> have enuff functioning units (on temp and on freq.) for all my R-1051s.
>
> Two of my four radios have bum six packs. I have several extra units, none
> of which work. I have spent many hours signal tracing through these
babies,
> having made up cables to allow them to be operated outside the case. But
> the problems elude me.
>
> Any suggestions about the most likely failure modes in these things. Might
> help narrow down my search!
>
> Jan Skirrow, VE7DJX
>
>
>
>
> ==========================================
> On Canada's Beautiful Wet Coast ....
>
> Visit: http://skirrow.org/Boatanchors/
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