On Mon, 13 Oct 2003 14:05:57 +0100, Paul Burridge, said...

Hi,

Let's say I'm trouble-shooting a circuit board with several stages of
RF amplification in addition to a primary source in the form of a
VCXO. I'd like to be able to bypass certain parts of the signal path
by the use of a jumper wire. This wire may need to be up to 4 inches
in length to have sufficient reach between stages. Can anyone see a
problem with this? I mean, rather than a single wire, should I use
some sort of grounded outer lead like coax to carry the signal?


i don't usually have to bypass anything to shoot. you look for last
known good, first known bad, with your RF probe/scope/sniffer/whatever
and go from there. lift an input component leg, terminate an output,
check signal, if good, plug it back in. find the stage that's bad and
check transistor DC levels first.

at HF
a wire might work
at VHF
getting dangerous. 50 ohm systems and coax looking good
at UHF
same as above but remove "getting"

you don't mention max allowed power out and freq. i know what your up
to, but can't remember the rules.

have you considered Mini-Circuits MMIC amps? 50 ohms in and out. if you
need more power, just put them in parallel fed with a wilkinson divider
and flip the divider around on the output for a combiner. alternately,
if the divider legs are too long at your freq, use the coil version. you
could probably get away with tearing open those 75 ohm CATV splitters
and hacking them. you'll loose a little power, but it's doable. a quick
solution.

too much time on radios and not enough on bot killing weapory. quick
solution for that... shotgun?

HTH,
mike