[Amps] Plate coupling capacitor value

[John Lyles]

The capacitive reactance Xc of the plate DC blocking ppcapacitor should 
be chosen so that on the lowest frequency it has a low value of ohms. 
This way it doesn't have a significant RF voltage across it, which 
results in heating and loss. On the other hand, if the capacitance is 
much larger in value than required for the lowest frequency, usually 
some self resonance in the capacitor will begin to act up on the higher 
frequencies. Also, a larger than needed capacitor may cost more. A 
single capacitor usually suffices in the application for amateur 
service. If two paralleled capacitors are chosen, they should be mounted 
on flat straps equidistance to the pi-net and to the plate. This will 
produce equal inductance for each cap, so that they share current well.

73
John
K5PRO

e
> Message: ę
> Date: Wed, 06 Sep 2017 21:51:52 -0500
> From: donroden at hiwaay.net
> To: amps at contesting.com
>
> Is there any hard or fast rule about how much capacitance to use
> between the tubes and the pi-net ?   if 1000pf is good, is 2000pf ....
> 3000pf better ?
> Better to parallel several 500pf Centralabs or use one big Russian ?
>
> Don W4DNR
>
> DonR
>