An effective HF/VHF bypass for HV can be made by paralleling several
unequal-value 10kV disc ceramic capacitors - using short leads, of
course. For example, 200pF is a fairly good bypass c. 100MHz. 1000pF
is good c. 30MHz, and 5000pF is good c. 3MHz.
- note - To check a disc ceramic cap for resonance, solder it to a Cu
strap and measure the self-resonance with a dip-meter. Why is this
important? -- above it's self-resonance, a capacitive reactance
becomes an inductive reactance -- i. e., inductive reactances do not
make very good bypasses. cheerz. Neil
On Apr 5, 2004, at 8:15 AM, Neil Carr G0JHC wrote:
There is a common 680pf "6kv" HV feed thru Capacitor on the market,
that
many seem to use, manufactured by Sprague, seen here
http://www.rfparts.com/caps2.html#high
I was just about to put one of these in my latest project to get 5kv
through
the RF chassis wall, but became nervous at the clearance, which is 4mm
from
HV pin to locking nut.
Pleas give me your opinion on this item. I have designed a min of
25-30mm
(2"+) elsewhere.
Does anyone run this device at 5kv or above and had problems?
Thanks for your time.
Neil G0JHC
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Rich Measures, AG6K, 805.386.3734. www.somis.org/
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