I have had good luck using several high voltage disc ceramic capacitors in
parallel. These are often quite cheap at hamfests and surplus stores. Look for
physically large capacitors with heavy wire leads -- 5/8" diameter for values
under 50 pF, up to about 1" dia. for higher values. Although I have a few 2 kV
caps, I rarely use them, preferring 3 kV to 6 kV ratings.
Don't bother with values over about 330 pF, since you MUST use several in
parallel to handle the current. My inverted-L is matched with about 1200 pF
shunt across the feedpoint -- I use six 170 pF 4 kV caps plus a couple smaller
values for fine tuning. They have handled 1.5 KW for the duration of a contest.
Not bad for a couple bucks worth of parts.
After tuning to get the final value, I solder the capacitor leads to two lengths
of #14 wire to make a single unit. I space the caps about 3/8" apart for good
air flow.
73, Gary
K9AY
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