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@hiwaay.net
To: amps@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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|