[R-390] Mica caps

[Perry Sandeen]

Yo Bubba Dudes!,
Wrote: 
Sometimesthe 200pf mica cap in the transformers goes south. I had one and they're abugger to find.
Well here's the bad news.  It's only going to get worse.  The A's are getting old enough to qualify for Social Security.  Longevity WAS NOT an OEM requirement.  Also the mica caps were not made or sped'd to the EIA value series that has been used for many years.
If you want to keep your A running with the least amount of effort heed my voice crying in the wilderness.
Go to Dan's small parts.  There you can buy SM caps starting at 1pF and going up in usually 1pF to 3pF increments into 33pF and beyond.  They are $.69 each.  You can then pad a value to what you need.  He also sells 2 different assortments of 50 assorted caps with 15 different values for $15.00.  This is the easy way by far.
The hard way is to go to Mouser/Dgi-key/Newark/Allied and pay $5 or more dollars each and then hope it's going to work.
Even if you go the hard way and get lucky, the same problem is going to arise again someday and probably sooner than you thinks as these mica caps are now starting to fail at a much higher rate than before.
This is just the cost of doing business with an A.

And if you want to save yourself future grief, if you haven't already, download the Almost Ultimate R390A ski tiff from the R390FAQ site, take it to Kinko's and get a large copy made.Why? Because when I drew it I earmarked all the problem parts noted on the reflector list for years.  Your going to need it sooner or later.

And a Chuck Rippel pointed out, in some cases the teflon covered wiring capacitance  had to be taken into account.
Regards,
Perrier