across the capacitance can be very many times larger than that at 50 ohms.
So, I need *to build a capacitance selection box with values from around
0-30nF with sufficient resolution to fine tune a hi-Q loop*. I will need
the
capacitors to be rated sufficiently high voltage to cope with any power
level I am likely to put into the loop antenna (almost certainly never
more
than 20-30W though).
My questions are these:
(a) what is the best *choice of capacitors* - type, voltage working, pulse
behaviour, accuracy, price?
(b) what is the *simplest arrangement* to give me the adjustment accuracy
and range I need with the fewest parts and fewest switches?
Any advice would be appreciated.
73s
Roger G3XBM
Well, to do 1nF to 30nF in 1nF steps, you need six caps and six switches -
1, 2, 2, 5, 10, 10nf caps
all in parallel, with a (toggle?) switch in series with each capacitor.
Martin GW3UCJ.
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