In a message dated 4/29/2011 10:59:29 P.M. Pacific Daylight Time,
towertalk-request@contesting.com writes:
> My 4L SteppIR with the 30/40 M trombone is on sawhorses in the front
yard. It was
down to replace the driven element motor. The climber and crane are
scheduled to put
itback on the tower tomorrow morning.
> After I replaced the motor, I ran an SWR check from 7.005 to 29.5. The
SWR ot the
lower end was 7.2, lowering as the frequency went up, til at 29.5 it was
1.0.
Considering the proximity to ground, I can accept that range.
> Today ( 10 days later) I checked again, and the SWR range had gone up
to 8.2 to 2.2.
Nothing has changed, except we had rain last night, so the ground is a tad
damper.
> How concerned should I be, and what would you check? I really don't
want to get it in
the air and have a problem.
What you're looking for is that it looks like an antenna - that
is, that there is a nice dip somewhere. Typically ground capacitance will
lower the resonant frequency but if it's got a nice dip, that's okay.
I didn't follow what 29.5 referred to. If the motors work normally
and you've got a dip (try other frequencies also), I'd go for it.
Cheers,
Steve K7LXC
TOWER TECH -
Professional tower services for hams
Author of the world's first tower installation book (available at
www.championradio.com)
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