[TowerTalk] Log Periodic Feed

[James Wolf]

Continuing the discussion on how to attach the coax to the “hot” boom of a Tennadyne T8 antenna.

 

As I assembled this antenna, I became increasingly confused and concerned about the feed system.   With this log antenna, instead of running open feedline wires crossing over to the elements, it uses two boom pieces and each is insulated from the mast and each boom is “hot”.  The instructions indicate and show how to attach the feedline to the bottom boom piece using a Collins type balun at the feed point which is at the forward end of the antenna.  

 

My concern is that of the coax shield separated only by the coax insulation alongside one of the “hot” boom pieces would couple and cause radiation (phase shift) problems with the antenna or at the very least radiate as it goes vertical down the mast.

 

Due to the element mounting method it is not possible to run the feedline inside the boom to the mast.   

 

Does anyone have any thoughts on why running the coax along the “hot” boom would be an OK idea?

And if not, how else would one feed the antenna?

 

Jim – KR9U