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

[Wes]

The beta or hairpin match is an L-network with a shortened driven element 
providing the capacitance and the hairpin providing the inductance.  It is not 
necessarily a single-band solution.

IIRC, the TH-3, TH-3JR and the TH6DXX all used them.

Wes  N7WS


On 5/18/2025 5:42 PM, Tom Hellem wrote:
> There is no difference between a hairpin match and a beta match, its just 2
> different names for the same thing.
> My understanding of them is that it's  a device for raising the feedpoint Z
> of a yagi, typically 25-35 ohms, up to 50 ohms. But when you build one, you
> can only adjust its length for one frequency band. I have never seen one
> used on a tribander, only on monoband antennas.
>
> Could this be another example of confusion on the part of the folks at MFJ?
> Maybe they got tribanders mixed up with monobanders and just stuck a beta
> match on the TH-3JR-S because they didn't know any better.
>
> All of the trapped tribanders that I have worked with, and it's been quite
> a few, were direct fed with no matching system. The  losses in the traps
> probably provide the extra Z to arrive at 50 ohms.
>
> It might be worth just removing the beta match altogether and see what
> happens.
>
> K0SN
>