Hello Dave, I think we had a similar question recently - and I have been told the PolyPhaser products are gas tubes - I haven't opened one up yet. TESSCO sells these online - you can find them here: https://www.tessco.com/products/displayProducts.do?groupId=90143&subgroupId=91046
Regards, John W. On Thu, Oct 16, 2014 at 10:23 PM, ed breya <[email protected]> wrote: > Of all device types, I think gas tubes are the best for this sort of > application - very low C, and high surge current rating. I'm picturing the > kind that are used in power supplies and such for limiting line transients > - about 1 cm dia and length with axial leads. I don't know what kind are > used in "lightning arrestors," if they are the same or scaled up in size. > > Whether you make it able to take a direct hit depends on how big of a hit, > your budget, and the environment of the antenna and lines. If it's the > tallest thing in a huge field in a lightning-prone area, then it could be a > big issue, but I don't think most people have that situation. > > You may want to look at the US National Electrical Code (NEC) for ideas - > I believe that subject is covered there. The main thing there would be > safety against injuries and fire, even if the equipment is destroyed. > > I think what you would want is kind of a pi network - the lowest impedance > path to ground at the antenna zone that can be practically realized, then a > high common-mode impedance (or even fusible) line to carry the signal to > the building, then another low impedance path to ground at the building. > This means that in my opinion, you should not put the feedline in metal > conduit unless it's essential for protection - or underground, which should > improve the grounding. You want the antenna zone to absorb the brunt of any > discharge, then use the higher line Zcm to hopefully give some degree of > isolation from there to the building. > > Ed > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
