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Re: [TowerTalk] Grounding Question

Subject: Re: [TowerTalk] Grounding Question
From: K8RI on TT <>
Date: Sat, 26 Mar 2011 18:03:05 -0400
List-post: <">>
On 3/26/2011 4:01 PM, Gene Smar wrote:
> Pete:
>       Electrically the method you describe is identical to mine and to
> commercial shield grounding kits.  However, mechanically your method uses a
> barrel connector plus two more PL-259s than the shield-only ground method,
> which can introduce additional points of failure in the coax subsystem.

True, but in over 50 years I don't remember ever having a PL-259 fail IF 
you don't count direct lighting strikes to the top of the tower. Those 
are the only connectors I flood with DC4 or DC5 compound.   OTOH I have 
had number of N-Type fail due to lightning and/or high voltage  at the 
legal limit with high SWR on 160 and 75. Even the lighteing strikes to 
the top of the tower did not cause the PL-259s to short even though they 
lost structural integrity and all of their silver plating yet they 
continued to work. Leaked but worked. <:-))

Why do I use N-type on 160 and 75?  UHF are difficult to find and 
usually very expensive for larger coax. Also I had about a 100 of the 
things.   With all the antennas, towers and masts and running SO2R I now 
have over a 100 connectors in use so it's far cheaper to purchase them 
25 or even a 100 at a time. Painful, but cheaper in the long run. <:-)

   In addition I have to either use a bulkhead connector or add a female 
connector to the coax coming down the tower. I'd rather add an extra 
connection than have to stock one more kind of connector.   As I use 
Davis BuryFlex(TM) for pigtails and LMR-600 for feed lines down the 
tower and to both the shop and house I'm not adding any additional 
connectors for the grounding.  I've never seen a femal UHF connector to 
fit LMR-600 although I do now have a few male connectors which I 
modified for better clearance.

I think I'll eventually replace all the LMR-600 connectors with 7-16 
DINs and use adapters where necessary.

As a side note, I have one drawer in the cabinets for coax connectors. 
One day I shut it and ... It dropped right off the draw slides and took 
out two of the drawers immediately below it.

I think I'm going to get three plain tool chests with flat tops and use 
those for drawer pedestals. Yes they are some what expensive, BUT even 
though the crew was instructed to grade the concrete floor high around 
the walls, sloping to the center and out the doors the entire floor 
drains to the  %$@ low spot that is along the South wall UNDER my work 
bench which is ruining the pedestals.

Three of those big tool chests are considerably cheaper and much easier 
than redoing the entire floor.Yes there is a very good material that is 
self leveling which would be a great improvement BUT in addition to 
having to take out all of that *stuff* in the shop, I'd have to 
remove the 5 or 6 coats of epoxy AND it'd cost between $2,000 and $3,000 
just for material for the amount I'd need for a 28 X 40' floor that's as 
far out as this one is.


Roger (K8RI)

>       The bulkhead method could be used at the base of the tower where you're
> likely to have connectors anyway, like where you might connect the coax to
> Polyphasers protruding from a steel enclosure.  Connecting to these
> Polyphasers would provide the shield grounding we seek.  However, at the top
> of the tower it might be easier just to cut away the coax jacket and install
> the ground connector kit and weatherproofing material.
> 73 de
> Gene Smar  AD3F
<snip for bandwidth>


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