FC390 Capacitor

[wcsd106]

I'm getting ready to attach a FC390 counter to a Cobra 148GTL I've been working on. The jumper mods have already been performed and it is ready to be hardwired to the 148 circuit board.

I looked through my parts bin and do not have a 68pf ceramic cap to use on the VCO connection.

I do, however, have a 68pf Mylar cap.

I also have several 82pf ceramics.

If I don't get a reply soon I'll just experiment, but I don't really see the harm in substituting mylar for a ceramic.. All in all I should just be providing an overkill on stability and quality to that capacitor.

Which one would you use?

 

[Captain Kilowatt]

Use either one. The mylar 68 pF is fine as is the 82 pF ceramic. The idea is to use a low value so as to not load the circuit it is connected too and in this application there is no power involved so pretty much any type of capacitor will work.

 

[wcsd106]

Thanks for the reply. I'll use the ceramic then.. they're much cheaper.

I wasn't sure how close to the 68pf it needed to be and if different capacitor value/type would change the impedance enough to affect the counter

Update: For the record 82pf ceramic cap worked just fine. Counter now works and displays entire frequency range of this radio from 26.815 to 28.725MHz gotta love 'The Mod' board