Steve, going back to fundamentals, you might try installing a Tee connector
on the output of the analyzer and connecting a 50 ohm load to one leg of the
Tee. With the other leg of the Tee open you should see a low vswr on the
analyzer. With the other leg of the Tee connected to the antenna, the vswr
would
be low if the analyzer sees an open circuit, or the vswr would be high if
there is a short circuit.
I assume there is a transmission line between the feedpoint and the element?
If so it needs close scrutiny for an open or short circuit.
The remaining thought is maybe there is an AM Broadcast station close enough
to QRM the Analyzer. I have measured as much as 5v rms on 75m antennas from
KRLD, a 50KW station about 10 miles distant.
Measuring vswr with a 100w transmitter will reveal this scenario.
73/k5gw
In a message dated 4/18/2008 8:47:37 A.M. Central Daylight Time,
K7LXC@aol.com writes:
Howdy, TowerTalkians --
I'm installing a 2L F12 80M beam. I'm not sure of the exact nomenclature
- it was a semi-custom order - but it uses the element coils close to the
boom.
I can't find a resonance anywhere (following the manual instructions). I
went directly to the feedpoint and skipped the balun, relays, etc. and I've
still got infinite SWR everywhere. Usually that's an indication of a
feedline
problem but I've got my MFJ hooked directly to the feedpoint and still no
dip anywhere. Not even a little one.
The elements have continuity and it's a pretty simple element; just an
insulated center feed piece, a coil and the rest of the element, so I'm
pretty
flummoxed why I can't see a dip. I've changed the coil length with still
nothing. What am I missing here?!?
ANY help appreciate.
Cheers,
Steve K7LXC
TOWER TECH
Cell: 206-890-4188
PS - Tom, N6BT, has been sort of helpful and there aren't any nearby AM
stations to cause problems with the MFJ.
**************Need a new ride? Check out the largest site for U.S. used car
listings at AOL Autos.
(http://autos.aol.com/used?NCID=aolcmp00300000002851)
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
**************Need a new ride? Check out the largest site for U.S. used car
listings at AOL Autos.
(http://autos.aol.com/used?NCID=aolcmp00300000002851)
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|