[TowerTalk] XM-240 and KT-36XA Interaction

[Tony Brock-Fisher]

I have a KT-36XA 9 feet above a 40-2CD. I have noticed a serious interaction between the two - specifically, the SWR on 40 goes above 3:1 when the XA boom is parallel to the elements of the 40 - i.e. the booms are 90 degrees to each other. I have not noticed any problems on 10-20 on the XA. I used to have the same setup with the KT-34XA and don't recall having the problem, so I suspect it is caused by the fact that on the '36, the parasitic elements are grounded to the boom by metal boom-element clamps, and this makes the boom resonant on 40. In my setup, the XA is on top, and the 40 is on a swinging-gate mount, so they are independantly rotatable. If I really need to, I can rotate the XA to fix the problem - but this would not be a good solution for multi-op. I think if you mount them on the same mast, with the booms  parallel, there should not be a problem. Anybody have a ferrite bead choke with an ID of 3 inches?

-Tony, K1KP