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
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Jim Brown
Sent: Saturday, May 17, 2025 11:18 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
On 5/17/2025 6:04 PM, Gary Mayfield wrote:
> We have also added a balun made from type 31 ferrite material.
Hi Gary,
Don't know anything about that antenna or have a solution for your problem, BUT
-- if that #31 is a lot of turns of transmission line wound around a 2.4-in
o.d. core, it is a Common Mode Choke, NOT a "balun."
Antennas like yours are designed for specific matching networks or feeding
methods. A choke is used between the transmission line and that matching
system, whatever it is. These matching systems are often called baluns.
And with respect to your problem and on-the-ground testing -- did you have a
long length of coax on it when testing on the ground, or just the analyzer
connected with a few feet of coax? Their matching networks often want to be
driven by that coax.
Also, study carefully as you can what the original matching system was.
With gamma and hairpin matching, both the length and the diameter of the
rod(s) matter.
73, Jim K9YC
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