[TowerTalk] 40m Beam: Problem - Attenuation and Static

[Richard Thorne]

The WX cooperated yesterday evening so I could climb the tower.

I disconnected the coax to the balun as well as disconnecting the balun 
from the feed point, then reconnected both.

During the disconnection process I did not notice anything unusual. I 
also opened the balun and everything looked normal.

Since and SWR analyzer was not useful for identifying the problem I took 
my Elecraft KX2 up the tower with it's own coax to connect to the balun.

After reconnecting the balun to the feed point I connected the KX2 to 
the balun and found WW0Y CQing.  The beam was pointed in the wrong 
direction but he did hear me for a very brief QSO.

A picture of the KX2 setup is on my qrz page.

I wonder if this is the first qso made at 120' on a tower?

At any rate the problem is now resolved.  I guess the 
disconnect/reconnect solved the problem.

Thanks for all the suggestions.

Rich - N5ZC

On 3/17/2019 3:00 PM, Richard Thorne wrote:
> I've had a strange problem develop with my JK 404C 4 element tribander.
>
>  - The signal is sometimes attenuated.  Per my Flex 6600, I'll show a 
> noise floor of -130db, when I transmit a bit the noise floor increases 
> to -120db.
>
> - After transmitting and the noise floor increases, I get a lot of 
> broad band static, which appears to be random and comes and goes.
>
> - The SWR on the antenna is excellent and doesn't change, which seems 
> to be strange with symptoms described above.
>
> - I'm using a 2 antenna WX0B stack match to combine the JK404c and a 
> F12 2 element delta 240 40m yagi.  I have absolutely no issues with 
> the F12 delta 240 going through the same feed line (from the stack 
> match) to the transceiver when the Delta 240 is the only antenna 
> selected on the stack match.
>
> Here's what I've done to attempt trouble shoot the problem:
>
> - disconnected the JK 404C feedline from the stack match and attached 
> an Elecraft KX2 directly to the feed line.  Same issues as described 
> above.
>
> The feed line is LMR-600 from outside the shack to the tower.  The 
> coax is direct buried, no pvc pipe.
>
> - From the shack to the base of the tower a run of LMR-600 about 195' 
> long.  RG-213 from the LMR-600 via SO-239 / female N adapters to 
> another length of LMR-600 (with the same adapters)
>
> - The LMR-600 goes from the base of the tower up to the where the 
> antenna is mounted.  The LMR-600 is attached to the tower leg inside 
> the tower, not outside.
>
> - RG-213 jumper from the LMR-600 to the balun/feed point of the 
> antenna.  At this junction I'm using a DXEngineering grounding block 
> with a 2" barrel so-239.
>
> All that being said has anyone come across the same symptoms of an 
> attenuated signal and static that was caused by coax adapters, bad 
> coax or a balun at the feed point?
>
> This particular antenna has a phasing line between two driven elements 
> with 1:1 current baluns at each feed point.
>
> I'm stumped at this point.  I climbed the tower this morning and 
> didn't see any obvious mechanical issues.
>
> Any ideas or other things to check?
>
> Thanks in advance.
>
> Rich - N5ZC
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