[TowerTalk] Entrance panels, feedthrough connectors, RF chokes?

Jim Lux jimlux at earthlink.net
Thu Aug 31 17:30:53 EDT 2006

Has anyone seen anything like a bulkhead PL-259 connector/feedthrough with 
ferrite toroids around it, sort of combining the commonmode choke with the 

Like a "bead balun" except more compact and integrated?

Likewise, with some sort of transient suppression combined?

And, as far as that goes... say you have an entrance panel with a half 
dozen or so coaxes coming in, and you want to prevent currents flowing on 
the outside of the coax.  Ferrite on the outside of the panel (towards the 
antenna) or ferrite on the inside (toward the rig)?  The panel is not 
installed in the wall of a shielded box (i.e. it's in the side of a house, 
for instance), so maybe it doesn't make any difference?

Since all the shields are connected together at one point (the panel), 
could one run the whole bundle of coaxes through a bunch of large toroids?

What about if there are lightning induced transients on the external coax 
(either common mode or differential mode)?

What about feeding DC power and control signals through the line (e.g. to a 
remote antenna switch)?

Jim, W6RMK

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