I would check the coax and balun connections with an ohm meter for
continuity and shorts. It is always important to take your time and make
good connections. I have never checked a Yagi with an analyzer when it is
near ground. The hairpin match just increases the feedpoint impedance.
The hairpin does not need to be grounded to the boom and the antenna should
work without it although the SWR will be slightly higher and the resonance
will be slightly shifted. Did you connect a transceiver and check it? If
the feedline connections are solid and there is nothing metal nearby
effecting it, I would suspect the traps. They could be wet, filled with
debris, have poor connections or just burned out from someone running 500
watts in a high duty cycle mode. If you're not getting anywhere and the lift
expenses keep adding up in might be time to consider an interlaced tribander
like a C3.
GL
John KK9A
Gary N0SD wrote:
]
Thanks Jim,
We did test with the long coax on the ground, and your point is well
taken about the balun vs a choke. We will take a fine tooth comb to our
hairpin recreation. I suspect that may be a contributing factor.
73,
Joe n0sd
[TowerTalk] HELP - Hy-Gain TH-3JRS
Gary Mayfield gary_mayfield at hotmail.com
Sat May 17 21:04:04 EDT 2025
Hello - We had a frustrating afternoon today trying to put up a Hy-Gain
TH-3JRS at the QTH of Rich, KE0EPY.
The antenna is previously owned, and we replaced the broken aluminum
matching wire (beta match) with one made of copper. We have also added a
balun made from type 31 ferrite material. Other than that, the antenna seems
to be all original. A few days ago, we tested the antenna on top of an
8-foot fiberglass ladder, and it had three nice SWR dips right where you
would expect for 20, 15 and 10 meters. Today before taking the antenna up
the tower, we checked it all again, by pointing it lifting it a couple feet
and pointing it straight up. Again, we saw 3 nice dips where they were
expected.
Once we mounted it on the tower the SWR went very high and only showed one
small dip just below 15 meters at 20.8 MHz. Thinking the coax had been
damaged we took a small jumper up in the lift and connected directly to the
balun but got the same results. Then we bypassed the balun - same results.
We removed the beta match and connected straight to the driven element and
got the same results. With the beta match removed the two sides of the
driven element are not shorted to each other or the boom.
We have the lift for another day. Any ideas/thought/suggestions will be
greatly appreciated!!
Thanks, and 73,
Joe - n0sd
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