[R-390] saga cont pt 12

[David Wise]

Leakage is a frequent failure mode in molded mica caps today.
Besides messing up the DC operating point, it spoils the Q.
And most of the ones I've seen, only leaked under voltage.
As some of the caps are in the R-390A.

Dave Wise
SWL in Hillsboro Oregon 

>-----Original Message-----
>From: r-390-bounces at mailman.qth.net 
>[mailto:r-390-bounces at mailman.qth.net] On Behalf Of Craig C Heaton
>Sent: Monday, September 27, 2010 1:34 PM
>To: ka9egw at britewerkz.com; r-390 at mailman.qth.net
>Subject: Re: [R-390] saga cont pt 12
>
>Brian,
>
>On mine, from memory isn't it 68 ohm resistors? I think you 
>will find the
>2nd ones in from the front panel have the least effect, 3rd 
>one in the most,
>4th one from the front panel a good 2nd place. 
>
>
>Craig,
>
>PS: Look out for the slugs! If you find one that is adjusted 
>just about to
>come out of the rack, a silver mica in that can is bad. 
>Another hint on bad
>silver mica caps in those cans is when, no matter what, one 
>octave loses its
>sensitivity. You go back get it peaked again and several days 
>later that
>octave has gone south. Most cases, just one RF can is the culprit. 
>