Feed Through Capacitor

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M1EEV
Posts: 6
Joined: Wed Jan 25, 2012 4:43 pm

Feed Through Capacitor

Post by M1EEV » Sun Feb 05, 2012 5:21 pm

Hi i have just built a small tin box and fitted my VCO into it.
But i am thinking of useing a Feed Through Capacitor to feed the DC.
Can anyone please tell me what value it should be?
My VCo is the 1249Mhz from BATC.
Thanks Chris.....

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G3GJA
Posts: 337
Joined: Sun Nov 20, 2011 3:44 pm

Re: Feed Through Capacitor

Post by G3GJA » Sun Feb 05, 2012 6:01 pm

1000pF is a readily available value for feedthrough caps and would be suitable for this application.

Clive

M1EEV
Posts: 6
Joined: Wed Jan 25, 2012 4:43 pm

Re: Feed Through Capacitor

Post by M1EEV » Sun Feb 05, 2012 7:12 pm

Thanks for your fast reply, i did have that value in mind.
have got them saved in ebay...Chris.

g4bbh
Posts: 74
Joined: Thu Mar 13, 2008 7:19 pm

Re: Feed Through Capacitor

Post by g4bbh » Fri Feb 10, 2012 10:27 am

I have a 1000pF feedthrough on the supply (12V) and an 8V regulator inside the VCO box. I am now wondering how to filter the data lines frorm the frquency controller board which is outside the VCO. Large feedthroughs would kill the serial data and clock.
As an aside I have noticed that any RF leakage around the VCO or input to the DigiLite board will make bias settings vary. If anyone finds the bias settings seem to drift and carrier is not always well nulled it is probably RF leakage around the VCO and DigiLite board RF section.
Dick G4BBH

g8byi
Posts: 23
Joined: Sat Mar 08, 2008 5:23 pm

Re: Feed Through Capacitor

Post by g8byi » Sat Feb 11, 2012 5:03 pm

Hi
I have used 1000pf feed throughs for the 3 pic data lines , no problems encountered with pulse shape etc.


Richard g8byi

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