[Boatanchors] Failing Mica Caps.

[BLIMPY]

Ok fellas ! I surrender !!
Several of you have written to say that " Yes Virginia Mica Caps Do Fail ".

All of you citing Collins Recievers incidentally.

Ok,  you'll get no arguement from me.
Voltage, moisture, poor manufacture, poorly spec'd devices, dirt, time take 
thier toll on everything under the sun.

Yes mica's do fail.
No, I dont get any Collins rigs through here to work on, so I yield to your 
specific experiences there.

I do however overhaul a LOT of recievers including many Zeniths and similar 
dating back to the mid 30's and etc.
It is exceedingly rare to encounter a bad mica in  these radios.  The radios 
I do commerically are guaranteed for 3 years..
the longest such guarantee in the USA.  I have been waiting over 23 years 
for the first radio to come back.
Your milage may vary.

Same deal with  the 50's-60's and later vintage transmitters and most 
recievers mere mortals can afford.
In these, about the dumbest thing you can do is start messing around in the 
VFO futsing with micas, npo's and etc.

Since I addressed my comments to a fellow who seemed to need basic advice on 
chosing bypass and coupling caps,
I gave him what I think is tried and true advice - change out the paper and 
electrolytics, and leave the rest alone, unless there is real cause to 
replace them.

After the radio switches and tube sockets are cleaned, tubes tested and 
replaced, that recapping done, any errant resistors dealt with... and the 
thing  aligned/  peaked/ calibrated and tested with voltage on it... then it 
MAY be necessary to fix an ailing mica.. if you can find one.   In a Ranger, 
it's not likely, unless the thing has been wet and moldy.

Every radio presents it's own unique set of "problems" which if you see the 
model often enough you become aware of.  SP-600's have  mica caps buried in 
them which are usually overlooked... so there you go.

But an SP-600  or a R-390 isnt a Ranger, which was the subject of  my 
comments.
73.