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

[Charles Tifft]

Couple Wilson Tribanders too. SYS1 and SYS36  come to mind.
W6RD

> On May 19, 2025, at 6:21 AM, Wes <wes_n7ws at triconet.org> 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
>> 
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk