[TowerTalk] HELP - Hy-Gain TH-3JRS

[Gary Mayfield]

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 at contesting.com> On Behalf Of Jim Brown
Sent: Saturday, May 17, 2025 11:18 PM
To: towertalk at 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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