[R-390] VFO End points

[Renee K6FSB]

Miles-
you are correct , do not, I repeat do not play with the stack.....I did 
it long time ago ( before the internet!) took more than a month to get 
it perfect!! I was ignorant enough to do it twice! and here I thought I 
had learned something back when I was young....hmmmmmmm hind sight is 
really good! learn from others' mistakes!
Renée


k2cby wrote:
> The standard Collins VFO contains three fixed capacitors in parallel with
> the coil: C701 (370 pF), C702 (10 pF) and C703 (10 pF). Two of these are
> tiny bits of naked mica with deposited silver on either side connected into
> the circuit by very thin wire leads.
>
>  
>
> Particularly if the VFO had gotten damp, these tend to deteriorate. When
> they change value they alter the spread between f(max) and f(min) of the
> VFO.
>
>  
>
> Before even thinking of diddling the linearity stack, try replacing these
> with NP0 ceramics.
>
>  
>
> So far as I am concerned, the linearity stack adjustment is strictly off
> limits. Strong men have been reduced to quavering wrecks trying to adjust it
> without the slotted shield cover that Collins used. (Why do you think Cosmos
> came along?)
>
>  
>
>  
>
> Miles B. Anderson, K2CBY
> 16 Round Pond Lane
> Sag Harbor, NY 11963
> Tel.: (631) 725-4400
>
> Fax.: (631) 725-2223
> e-mail: k2cby at optonline.net 
>
>
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