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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