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Re: [Amps] Ceramic capacitor ratings

To: <garyschafer@comcast.net>, <amps@contesting.com>
Subject: Re: [Amps] Ceramic capacitor ratings
From: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 13 Apr 2007 23:09:21 -0400
List-post: <mailto:amps@contesting.com>
Now the question is about ceramic padder capacitors used in 
the plate tune
circuit. There is a variable plate tune cap that is 23-347 
pf that is in
series with two (parallel) ceramic small door knob type 
caps. The ceramic
caps are 100 pf each for a total of 200 pf in series with 
the 23-347
variable cap.>>

You somehow have to take the RMS voltage across those caps 
times the reactance to find the current.

You have to treat it as a 200pF in series with whatever 
capacitance the air variable is set at. Each cap gets about 
half the current.


I am wondering about the current carrying capacity of these 
capacitors in
the tank circuit being in series with the variable cap as 
all the tank
current is going thru those caps.>>

Not all of it, but most of it is.

 Now with a better tank coil that is more
efficient I would guess that the circulating current is 
higher than it was
before.>>

Not me.

Also will they handle the current in this configuration at 
higher
frequencies if I try to put the amp on 15 and 10 meters?>>

I'd get rid of them Gary. They are just as good an idea as 
the toroid was.

On ten meters, they do virtually nothing to reduce maximum 
C. They might even increase it! The only place they have an 
effect is on lower bands, and there they can cause a drift 
problem. Get rid of them. Throw them in the same pile where 
the silly toroid idea went.

73 Tom 


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