[MRCA] R-390A query

DSP3 jeepp at comcast.net
Thu Apr 28 10:28:54 EDT 2016


Steve, Breck, Dale, everyone...

Got the R-390A fixed.  All comments posted, here, moved the effort 
forward and this a.m. got the cam set with the mark, correctly, and that 
was that!  The thing works great on all bands now.  I really appreciate 
the aggregate of experience, here, and the willingness to spread the 
knowledge.  The only remaining issue is the replacement S-meter.  I've 
never had a meter movement failure quite like this.  The needle sits at 
20 db, at rest.  It does not move with signal applied.  An ohmmeter will 
make it pin to the negative side but, reversing polarity, no movement, 
whatever, in the up-scale direction.  Curious.  A substitute 500ua meter 
gives "proper" movement but compressed at the lower 1/3 of the scale. 
Again, I'll inquire as to what the correct movement necessary.

Jeep - K3HVG



On 4/28/2016 6:57 AM, Steve Hobensack wrote:
> Jeep,
>
> Check for signal output from the crystal deck. It has a big number wheel near the fron panel looking down from the  top.
> The numbers indicate  the band. Somewhere in the manual is a list of crystal frequencies vs band number. The gear clamp holding  the shaft that goes through the crystal deck has to be aligned just perfect, otherwise some bands won't work. Also there is B plus on one side of each ceramic trimmer ( a bad thing) , the trimmers can go bad. I used a blocking cap.
> Look deep into the clockwork as you turn the megacycle change knob. Be sure there is no gear clamp slipping on  the crystal deck shaft. Also check for mechanica alignment. Put the frequency on 07 (plus sign) 000. If it is aligned properly, all the egg shaped cams will point to a scratch mark or paint mark on the fraim work. If it is not mechanically aligned, chances are that a gear clamp has slipped or is broken.
>
> Another place to ask for help is  the r390 reflector. it is at mailman.qth.net. You must go through a sign-up procedure.
>
> Steve N8YE
>

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