[Milsurplus] Micamold caps

[john p hutchins]

Richard, Brad, Group -

I am in the process of restoring 4 BC-348R receiver's

I have tested the Postage Stamp Mica's using a Sencore Z meter in 2 sets.
I recommend: initially not replacing any Mica's at all.  Also note that 
most of the Mica's are not under a lot of  voltage stress.
That being said, Check the Mica Caps that feed the tuning Cap to see if 
they are in tolerance.  I did find one Mica while not leaky was way out 
of tolerance.

I agree that:
All the Paper Caps will be leaky or shorted by now.  These are in the 
IF/AF section and Power Feed section under side.
Note:
    There is a Paper Cap hidden  inside the OSC can, BC-348(KLR) 
series,  must replace it.
    The .05uf AVC timing cap in the Audio/Coil Can may be bad.  If so 
mount a new one else where.

Check the resistors   I have found some way out of spec.  Noticed they 
do not take heat well,  some that I have left in which were in spec were 
out of spec after replacing the bypass cap.  So heat sink the resistor 
leads with an alagator clip and a bit of foil.

Quandary:
The method of  replacement of the .5uf /250WVDC  that are in metal cans 
in the power section:
   1. Punt and place a mil spec terminal strip from Keystone with .5uf 
/500WVDC from Mouser:?
   OR
   2. Remove the guts from inside the metal cans, and stick the .5uf 
/500WVDC from Mouser in the cans?

I purchased a cheap 150W Chisel soldering iron to attempt option 2.  
Right now it takes me about 1 hour to remove the guts.  Using a small 
width wood Chisel, Solder wick,  8x8 plywood base wrapped in foil to 
collect any juice.

Good luck
Hutch




Richard Arland, W3OSS wrote:

> Hi Brad:
>
> I have a BC-312 that I am going to restore later this winter. I was 
> wondering the same thing...are the Micamold caps worth the hassle? I'm 
> interested in the replies you might get on this question. Al Klase, 
> N3FRQ, told me that they were a real pain in the tail to replace. Just 
> wondering if it is worth the trouble.
>
> 73 Rich W3OSS
>
>
> From: "Brad Latta" <bl_6000 at yahoo.com.au>
>
>
>> Just wondering about these black Micamold caps in this
>> BC-348. Is it worth replacing them all?? If so,
>> is there a modern equivalent with the same size & type
>> of mould, & a similar voltage rating? They don't seem
>> to have a sharp resonance 'dip' when measured on my
>> capacitance bridge.
>>                       Regards, Brad
>
>
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>