At 432MHz you might be able to put a 1/4-wave stub in the HT feed,
depending where you put the feedthru in the anode chassis, a 13.5cm
length of RG400 (or similar) PTFE coax grounded at the feedthru end and
open at the tube/anode end might give you an additional 15-20dB of
isolation and allow you to use cheaper bypass caps...
Just an idea...
On 10/02/2012 20:34, Larry wrote:
> Yeah, it's for a 432 amp. At that frequency the series inductance of a
> single "normal" disc ceramic is enough to prevent good bypass action.
> Results in a lot more 432 energy running around on the HV line than I like.
> YU1AW calls for a cap made from FR4 PCB material. Even though I etched
> back the edges and hi-potted the thing, it still managed to prove that
> my HV supply fault mitigation system actually works!
> I have some 270 pF/6KV discs that I've been playing with. By cutting off
> the leads and soldering directly to short pieces of 3/8 inch wide copper
> strap and using several in parallel, the network analyzer suggests that
> it might work. I will try that if no reasonable feed through cap shows up.
> Thanks to all those that responded with vendors. Nothing seen so far
> looks suitable for my purpose. BTW, Surplus Sales is #1 on my list of
> "never again" vendors.
> 73, Larry - W7IUV
> On 10-Feb-12 12:04 PM, Carl wrote:
>> Any reason you cant use a ceramic feedthru and a disc cap for bypass?
>> Works for me at the 1500W level thru 222 MHz.
>> ----- Original Message ----- From: "Larry"<email@example.com>
>> To: "AMPS"<firstname.lastname@example.org>
>> Sent: Friday, February 10, 2012 12:25 PM
>> Subject: [Amps] HV feed through capacitor
>>> Can anyone suggest a source of high voltage feed through capacitors. I
>>> need 5 KV minimum and 270 pF to 1000 pF. Any leads to a supplier would
>>> be appreciated.
>>> Thanks& 73,
>>> Larry - W7IUV
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