[R-390] R-390 Q of Caps and tuned circuits

[Jacques Fortin]

Hello Dave,

Thank you for all those measurement results.
For the ceramic caps, I already mentioned that some ceramic caps (especially
the NPO ones) can be as good as the SM ones, but some made of different
ceramic grades are really worse, to the point that a given one prevented the
17MHz xtal oscillator stage to drive the R-390A first mixer with sufficient
amplitude.
And this was the starting point for this topic.
I believe that Larry recommendation is: use a SM replacement cap where mica
ones are used in the R-390A, unless you can measure that a ceramic
replacement is good enough for the task.

73, Jacques, VE2JFE in Montreal