rparigoris wrote:
> Before I bond top on, I want to test power and SWR of radios and try and tweak
location and fix any problems that may pop up like pitch indicator signal wire
catching noise from radio transmission or??
Well, SWR is dependant on the environment of the antenna. Be prepared to
see some changes after you bond on the top, install a strobe on top of
the fin, install a tail wheel, or even do some painting. The antenna is
most sensitive to changes in the environment of its outer ends. If you
happen to have an SWR meter, make sure to fool around with some metal
parts near the antenna, to see what the influence is. Use gloves for it,
as RF might actually bite you quite a bit. If you want to be cool, hold
a transfluorent tube (spelling?) near the antenna and watch how it
starts glowing as if it is connected to the mains. A LED with some wire
attached to its pins is also neat.
Anyway, the moral is: Best leave the SWR-tuning till the bare end. That
is, leave the antenna a bit too long (best SWR match on the lower part
of the frequency range) and do the final tuning when the airplane is
ready (including the paint). It is easier to clip something of the
antenna than to have to enlarge it.
Oh, and before I forget, try to lead the coax away from the antenna in a
90 degree angle for as long as possible. The shield of the coax will
pick up the radiated signal if it is parallel to the antenna, and
radiate it further down again, and this is what you want to avoid.
Best regards,
Frans Veldman
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