[TowerTalk] F12 80M beam

[TexasRF at aol.com]

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 at 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.  



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