[R-390] Update on R390A, open question regarding scope and options fir lubrication

[Jacques Fortin]

John, unless that you are equipped to test the Micamold cap with 300Vdc applied (their manufacturing voltage rating) to confirm that they have less than 10nA of leakage, wait for the new manufacture 1kV one.

I believe that the recommendation to change C327 was made because of the trouble involved with the RF deck removal to change any of the parts within.
Since then, many original mica caps inside the IF transformers were reported to fail (the thunderstorm noise problem).
But here also, they will not ALL exhibit failures, as this is just a probability.
Failure of the early type "postage stamp" mica caps is essentially due to their long-term casing permeability.
Some mica caps were made to never fail, like the Corning Glass Works (CGW) ones that have a glass encapsulation.
But as with any electronic equipment ever made, all depended on the cost vs reliability criteria.

73, Jacques, VE2JFE in Montreal