[Amps] Plate blocking cap voltage

[John Lyles]

If the capacitor is a blocker, then you would want it to have enough 
nanofarads to make a low value of Xc at the worst case (lowest) 
frequency, while not being far past self-resonance into higher XL.

Figuring the highest reactance possible, and the line current through 
it, you should have a low RF voltage across it. In that case, then it is 
withstanding the B+ voltage for the most part. With plate modulation, it 
would of course be higher. Assuming that there are transients, 
overshoots when energizing a power supply, and occasional high line 
voltage, you would take this value and add some safety factor. Caps 
typically have a working voltage rating, and you should  be somewhat 
under this for long life. I don't think 3 times the HV is necessary. I 
concur with Carls suggested 5 or 7.5 kV ceramic caps.

73
John
K5PRO


> Date: Fri, 6 Apr 2012 17:33:05 -0400 (EDT)
> From: mikflathead at aol.com
> Subject: [Amps] Plate blocking cap voltage
> To: amps at contesting.com

> What is the rule of thumb for the plate blocking cap voltage? 2 times high voltage, 3 times high voltage? This will be for a 4-1000 for 6 meters. Thanks Mike