[TowerTalk] Fwd: Terminate braid at top of tower...or not?

[Roger (K8RI) on TT]

On 11/2/2014 1:04 AM, Jim Brown wrote:
> On 11/1/2014 6:01 AM, Hans Hammarquist via TowerTalk wrote:
>> Using a metal box to contain your current choke is OK

I  install the chokes as close to the antenna feed points as possible 
and ground the braid(s) at the top and bottom of the tower. Before they 
connect to the remote antenna switch.  I use bulkhead connectors 
through  1" X 1/8" Aluminum angle through the one side of the angle
The chokes have the coax and connectors waterproofed with flooded heat 
shrink, liquid electrical tape, and sealant tape where appropriate.  The 
connectors and bulkhead connectors add so little loss under 30 MHz it's 
not worth worrying about.  Grounded top and bottom of the tower and at 
the SPG where they go through Poly Phasers mounted on the grounded plate.

My chokes are pretty much open to the elements.  I try to increase the 
cooling and do not worry about the elements. (note the 1/4" spacing) 
I've never noticed and effect from snow, rain, or ice.  The wind moving 
the antenna shows more effect than the elements on the choke and that so 
tiny as to easily be neglected.  I can read the SWR and other stats to 4 
decimal places and only the last place moves much. Once on a great while 
I see the third place move .  I agree with Jim. Actually I use his 
figures for building the chokes. They work very well.  Feeding a half 
sloper on 160 at the top of the tower is a good test.

73

Roger (K8RI)


>
> I disagree, because the box contains any heat produced in the choke, 
> reducing the dissipation of that heat to the outside air, thus 
> reducing the power handling of the choke.
>
> The reason for bonding coax at top and bottom of a conventional tower 
> has nothing to do with the shack, but rather is to keep the shield of 
> the coax at the same potential as the tower, with the intent of 
> reducing the likelihood of arcing between the coax shield and the 
> tower in the event of lightning. In other words, it is to protect the 
> coax.
>
> 73, Jim K9YC
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk


-- 

73

Roger (K8RI)