Hi Dave,
I have some design experience for POTS lightning protection. GDTs were
sometimes used but by the end of my design career we were using mostly solid
state devices (TVS and other SCR like devices).
Our golden rule was to avoid turning common mode surges into differential mode
as even the solid state devices would have differing turn-on thresholds which
would result in higher voltage stresses on the downstream electronics. This
meant the protection would go only across tip to ring and never tip-to-ground
or ring to ground. GDT's were even worse in this respect.
Having said that, I would recommend you dig around for articles written by K3NA
related to phased array receive antennas used on Ducie etc. He thought through
protection schemes that involved GDTs, Fuses and TVS solutions. Very thorough
designs.
I remember his designs were documented in the Sept/Oct 2008 and Nov/Dec 2008
NCJs but I was not able to find an archived copy on the web, though this seems
to be a version of what I remember:
https://ncjweb.com/bonus-content/200807NCJVP6DXreceiveantenna1.pdf
73,
Ken - WO1N
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|