I haven't actually built anything out of it, but the ARRL UHF experamenter's
manual seems to be well written. Get a copy if you're serious.

In general you get to a frequency/power level where you need to toss the
notion of using discrete componants and start using distributed (i.e. some
variation of a transmission line) instead. This happens sooner at higher
power levels (1500W amplifiers start showing plate lines at 2 meters).

One of these days I _am_ going to build some VHF circuits -- really!

"Paul Burridge" wrote in message
...
Hi guys,

I've just been doing some calculations out of sheer curiosity. It
turns out that to make a tank circuit for 450Mhz (which isn't *that*
high a frequency by today's standards) would take 5pF || 25nF. These
are both *very* low values. 5pF is getting perilously close to being
seriously affected by circuit board stray capacitance and 25nF isn't
much better; little more than a couple of turns of wire, I guess.
What does one do in such circumstances? Should one be thinking in
terms of etching these values out of the PCB by the time one gets of
to these frequencies, or is it still acceptable to make them up out of
discrete components?

p
--

The day Microsoft make a product that doesn't
suck, they'll be making vacuum cleaners.