Inductance Sleeve and bends:
I would use a 2" diameter rigid (steel) conduit or more as needed as a
'sleeve' for the building cable entrance. The sleeve and would be
connected to a ground rod system on the outside within a couple of feet
to earth.
The conduit would look like a "lump" mutual inductance to potential
lighting traveling along the RF transmission lines.
If I wanted the benefits of PVC for longer buried runs or to just to
protect the transmission lines for other reasons, I would then use a
steel sleeve around the PVC sleeve and grounded as indicated above.
Next, I would route the RF transmission lines to enter the sleeve from
the outside at a near 90 degree angle as is possible. This would add
another "lump" inductance to potential lightning from entering the
building.
Finally, I would ground the transmission lines at the point where they
leave the tower and near to the base of the tower as possible; and,
again making a 90 degree angle bend away from the tower as is feasible.
Carl, NW8Z
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Les Kalmus
Sent: Sunday, May 16, 2004 4:26 PM
To: 'GALE STEWARD'; 'towertalk reflector'
Subject: RE: [TowerTalk] Low Inductance Ground Idea
Arrggghhh.! Great idea, 3 months too late for me.
73, Les W2LK
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of GALE STEWARD
Sent: Thursday, May 13, 2004 11:11 AM
To: towertalk reflector
Subject: [TowerTalk] Low Inductance Ground Idea
A few days ago, I observed two plumbers who were
subcontracted to build and install some new hot water
manifolds/valves for the heating system that serves
our lab building. They were using some large diameter
copper pipe, 2.5 - 3 inches . Later, it dawned on me
that I should have used 3 inch copper instead of the 3
inch PVC that I installed through the wall to bring my
coax and control cables into my basement radio room.
This would provide a low inductance path from the
radio room to the outside ground system as well as
providing a raceway for the various cables. I wish I'd
thought of it sooner! One of the plumbers told me that
the normal elbows (90 and 45 deg.), couplings, T's,
etc. are all available in copper. Apparently, almost
all the configurations you could build with PVC can be
constructed in copper also. It would be a pain to redo
mine now but might be worth considering for "new"
construction.
73, Stew K3ND
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_______________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any questions and ask for Sherman, W2FLA.
_______________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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