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
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