On Sun, Nov 04, 2001 at 07:51:18AM -0500, KZ2G wrote:
> Ok, gang. Here's a weird one!
> while stationary. no change in swr. the swr only sways high and low as i
> drive, and van moves. i have not noticed this on ssb or other bands. only
> on 10-meter FM. any suggestions?
Hi Bob.
You're likely guessing the correct situation. I think you'd notice the
effect more on FM as it is a full duty cycle mode (constant power out)
than on SSB where the power varies greatly. There is probably little
doubt that you have some sort of situation where a panel or even the
dimension of the van contributes to a resonance at 10m, thus why the
effect isn't noticed on other bands (but, then you're probably not using
FM on those bands so try a dead AM carrier or CW carrier sometime).
Now, do you notice a change in received signal strength as the van is in
motion? It would be interesting to know whether the levels improve or
deteriorate with increasing SWR.
As for a fix, perhaps a piece of plexiglass mounted in such a way so
that the fiberglass portion of the whip is held vertical. Bracing it to
the luggage rack or other point near the top of the mast may help
considerably.
73, de Nate >>
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