[Amps] plate bypass caps

[Roy]

About,

"I have quite a few of the old-style transmitting mica caps (C-D, Sangamo,
Solar, etc.).  Are these okay to use in a nearly-legal-limit amp for either
plate-choke bypassing, or antenna load padders?  (etc.)"

In at least one edition of my Editors And Engineers Radio Handbooks, it 
stated that mica caps are not suitable for HV bypass application service 
because of "dielectric molecular migration."

I presume someone did not simply make this up. There must be basis for such 
a flat warning statement.

73,  Roy,    K6XK