Couple Wilson Tribanders too. SYS1 and SYS36 come to mind.
W6RD
> On May 19, 2025, at 6:21 AM, Wes <[email protected]> wrote:
>
> 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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