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Re: [Amps]  LF oscillation caused by defective plate choke?

To: Jim Thomson <jim.thom@telus.net>, amps@contesting.com
Subject: Re: [Amps]  LF oscillation caused by defective plate choke?
From: peter chadwick <g8on@fsmail.net>
Reply-to: g8on@fsmail.net
Date: Wed, 09 Oct 2013 13:03:37 +0200
List-post: <amps@contesting.com">mailto:amps@contesting.com>
>###   250 uh is fine for the plate choke.     Instead of the 1000 pf bypass 
>cap,  use 2-3 x 4700 pf disc ceramics.     That combo makes for an excellent 
>lower freq bypass cap.  
Then wire 1-3 x  500pf ceramic doorknob caps in parallel with the 4700 pf caps. 
  The 500 pf caps make for an excellent higher freq bypass cap.<  


You will have about 1 volt across that combination on 80m. Using 1 4700 pF cap 
and 1 500 pF cap in parallel will give 3 volts: then a 50 microhenry choke and 
another 4700 pf will drop this to 27mV and you have saved 1 or 2 500 pF caps 
and 1 4700 pF cap and got a better result. Just adding capacitors gets to a 
state of diminishing returns.

73

Peter G3RZP
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