[time-nuts] GPS-Attached Equipment Lightning Protection

Alan Melia alan.melia at btinternet.com
Fri Feb 29 20:33:44 EST 2008


Hi All, all the comment has been about in-line protectors so far. We in the
UK do dot have the ferocity of lightning that is seen in some parts of the
USA but surely like all problems "prevention" is better. It is probably not
100% but would it not be better to have a higher metal rod say 6 feet above
the GPS antenna spearately grounded as with a building protection system.
The GPS antenna should then be placed in the "cone of protection" of this
rod. The likelyhood of getting any significant voltage on the centre
conductor I would think would be very small. The most likely scenario is for
induced voltages/current on the braid due to nearby strikes. This should be
grounded in a way that does not allow the whole ground system that it is
connected to to to be "pulled up".

As has been stated if you do get a direct hit on the GPS antenna nothing
will save your kit, but again (I believe I am right here) the vast majority
of the current from the strike will flow down the braid (if it doesnt
vaporize it), So grounding the braid, preferably outside the premises if a
good idea. The size of the antenna is such that the build up of static
should not be significant....it is not a 200 foot long wire as I use on MSF
!

If this is rubbish please say so but it sounds much more sensible way of
proceding to me.

Cheers
Alan G3NYK





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