[TowerTalk] Placement of coaxial matching stub at yagi feedpoint

[David Robbins]

what kind of matching network does that use??  if it doesn't have something like a gamma or something else with one side connected to the boom then I wouldn't use a stub match like that.

a general note for open circuit stubs:
cut the center conductor back about 1/2", insulate the end of it with something that won't melt, then solder the shield closed over it.  this leaves it as an open circuit but stops noise from the shield from getting coupled into the stub.


Oct 13, 2015 10:23:25 AM, bill at conwellpdx.com wrote:

I'm doing some EZNEC modeling - looking at converting a KLM 40m 2 element
yagi to 30m.



The feedpoint impedance is about 35 + j25 ohms. By shunting it with an open
stub of about 100 inches of 75 ohm coax, I get a good match.



I know I'll need to keep the open end of the stub away from the boom, etc.
But is there any other reason the stub couldn't be laid-along, and taped to
the boom? Or coiled nearby? I think not, but wanted to tap the crowd for
collective wisdom.



Tnx,



/Bill, K2PO

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