Topbanders,
The relatively inexpensive ceramic caps can be used effectively by simply
taking two small aluminum plates or two single sided Glass Epoxy circuit
boards and drilling holes to accommodate paralleled capacitors of smaller
common value to distribute the current. Say 300 Pf is needed, use 3 100 Pf
units at 7.5 or 10 Kv. By using smaller capacitor values you may then use
your small value Teflon dielectric coaxial caps to fine tune the remanding
balance. These components will work fine at 1.5Kw. For those of you running
more gas vacuum caps may be a necessity.
The problem is ESR (equiv series resistance), not voltage. Ceramic
single layer caps (especially HV types) have high series resistance
and also have poor temperature stability so they drift.
If that was a simple single capacitor gamma adjusted for 1:1 SWR,
current through the cap would be only sqrt of P/R. A mere 5.5
amps at 1500 watts, and bandwidth would be wider! With an omega
match it can be almost anything more than, and never less than 5.5
amperes..
That's the price we pay for less tower work! ;-)
73,
Bob KG7D
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