[TowerTalk] control cables lightning protection
K8RI on TT
k8ri-on-towertalk at tm.net
Thu Jun 23 23:52:34 PDT 2011
On 6/24/2011 1:15 AM, Kostas Stamatis wrote:
> Hello to all...
> I want to protect from lightning and static charges my rotator cable as a
> controller cable for a switch. I have seen some solutions in DXengineering
> but i would prefer a reliable homebrew solution. Anyone with some ideas?
Diacs were mentioned, but those are more of a control device. Neon
lamps (NE-51s) work well with tube input and control but are a bit high
in voltage for rotator control.
For low voltage protection, I'd (1) keep the cables inside the tower and
bypassed to the tower at the rotator and base of the tower. The problem
with solid state circuits is the need for a low clamping voltage. They
make some huge Zeners with a 3/4" threaded base which will handle huge
current. Used are normally very cheap, but new are very expensive. the
nice thing about the big zeners is you can get one just a few volts
above the maximum working voltage of the circuit. These are one place
where I do favor MOVs. As the rotator lines are low voltage and
relatively protected by their very nature *IF* they are protected at the
rotator and base of the tower the voltage is unlikely to rise very high
and MOVs may last a very long time...but no guarantee. The same with
the massive Zeners.
There's the possibility of using 0.1 uf disk ceramics (You need a low Z
at 1 MHz) on each of the leads at the rotator, and those or zeners or
MOVs at the base of the tower and bulkhead connector at the station
I think most rotator damage comes from cable pick up, or from wiring
pick up in the house with the current going back to the rotator.
73 and good luck,
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