[TowerTalk] RFI, BN-86, and Choke Balun

[Brian Rehmer]

For sometime I have been struggling with noise (S4-7) on HF bands with my TH-5DX tribander.  I have ~125 feet of RG-8 routed to a BN-86 at the antenna feed.  There are several other feeds that are bundled together for 40, 6, and 2 meters in the same run up the tower.  The cables route to the tower from my second floor radio room inside my house.  So, there are lots of things that can couple to the outside of the feeds.  I am considering adding common mode chokes to reduce/eliminate the noise.  Alot of the time the noise covers the entire 15 M band. I can take a small loop and couple to the feeds at base of tower and other spots along the feeds and see the noise and it varies with position.  It seem this points to common mode as culprit.  So, there are lots of things that can couple to the outside of the feeds.  I am considering adding common mode chokes to reduce/eliminate the noise.

 Question is should I add the choke prior to the BN-86 or replace the BN 86.  I expect I may need to add chokes to each of the other lines too, but where.  Should I add in the shack too or just exit from the house to the tower.  Ugh, it could need both - getting to be alot of chokes.
Thanks,
Brian 
KC4KK