[R-390] parts in RF deck

[Dan Merz]

I would GUESS,  the center section of the tunable filter is isolated more from adjoining capacitance by the two 1.5 pf coupling caps c281-2 so needs more fixed capacitance to enable tuning with the parallel variable. All three cans are tuned same at same two frequencies using variable cap and slug tweaks. Any adjoining capacitance from B+ to ground probably adds more to the outer cans in the filter than to the more isolated center can. I'm not the guru you were looking for but that's my thoughts. Regards, Dan

Sent from my iPad Air2

> On Aug 22, 2016, at 3:07 PM, <wb3fau55 at neo.rr.com> <wb3fau55 at neo.rr.com> wrote:
> 
> So a question to our 390A gurus.  In the 1st  variable IF,  the cans-z213-1 -2 -3,
> there is a 51pf  cap at 213-1.  There is 68pf at z213-2, and  a 51pf  at z213-3.
> Why does z213-2 have a 68pf  and not a 51PF?  
>  Another question-  T207 at the 17mc xtal osc.  there was a missing 100pf cap.  I  replaced it with a 90pf.  Will that be OK?  thanks folks  Russ.
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