[Milsurplus] BC-348R restoration parts question.

john p hutchins olegerityincj at austin.rr.com
Sat Nov 11 01:41:09 EST 2006


Group -

Off frequency after adjustments and alignment to documented procedures. 
OSC and Detector may be the problem.

I did note that there are "undocumented" mica trimmers in the OSC can.  
I assume to true up the values on the Tuning Cap feed?  I may have to 
replace some of the CAPS the feed the tuning CAP.

MICA caps:
Compiled a list of frequency critical parts.  These are parts in my 
opinion that play a large part in keeping the DIAL tracking to 
calibrated to frequency.    These are the CAPS that couple the Tuning 
capacitor to the Coils.  These are high precision parts.

Where would one find a replacements?

I assume that direct replacements are not possible; Need to create the 
required capacitance from a sorted lot of capacitors.  What 
considerations would one observe while creating these capacitors:
Do I keep them MICA's?
How to mary up the values?

Please Email directly off list with any suggestions.

Thank you
Hutch

Example of critical capacitor, split values I think will work:
     2pf +/- .5 pf Standard  mouser  -          2pf +/- .5 pf  
CD10CD020DO3, CD15CD020DO3
    85pf +/-3%                   mouser  -    ??82pf +/-2% + 3pf+/- .5 
pf??          OSC.  <<-
                                                            ??56pf+/-1% 
+ 30pf+/-2%??    A better split I believe OSC.  <<-
  100pf +/-5% Standard    mouser -       100pf +/-5%     CD15FD101JO3
  200pf +/-3% Standard    mouser -       200pf +/-2%     CD15FD201GO3
  210pf +/-1.5%                mouser  -  ??100pf+/-1% + 
110pf+/-2%??        OSC.
  400pf +/-1.5%                mouser  -  ??200pf+/-1% + 
200pf+/-1%??        DET.
  500pf +/-1.5% Standard mouser -       500pf +/-1%    CD15FD501FO3  OSC.
1700pf +/-2%                   mouser  - ??1600pf+/-2% + 
100pf+/-1%??       OSC.
2650pf +/-2%                   mouser  - ??2400pf+/-1% + 
250pf+/-1%??       OSC.
   .01uf +/-10% Standard   mouser -        .01uf +/-5%    CD30FD103JO3





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