[BC] More thoughts about AM transmitter lightning

[dynotherm at earthlink.net]

While the new installation does not have johnny ball arcs, the ball gaps
at the tower bases must discharge when the tower potential becomes high.
It is interesting that this discharge is not noticed as the plasma also
effectively shorts the RF to ground momentarily.

There may be an explanation in the number of electrical degrees
between the short and the Tx. In fact, the phase differential
between short and Tx is equally likely as the reason for hiccups 
going away as the long insulators. There is no way of knowing
positively which (or both) it is in this situation.

Some towers put on "light shows" before a thunderstorm moves in
and wets the insulators without significant effect on the Tx. In
other cases of tower guy systems with built-in "fireworks" in the
guy system, the Tx starts muting with every flash. Often the
difference can be found in the phase angle between the Tx and the
tower(s).

Phil Alexander, CSRE, AMD


-----Original Message-----
>From: Gary Peterson <kzerocx at rap.midco.net>
>Sent: May 22, 2008 10:01 AM
>To: broadcast at radiolists.net
>Subject: [BC] More thoughts about AM transmitter	lightning
>
<snip>
>  On both of the new towers, I
>specified long insulators where the guys attached to the tower, where the
>guys attached to the anchors and at the midway point of the upper two sets
>of guys.  These insulators are several feet long and appear to be something
>like fiberglass rods.  I have seen these used by the power industry.  In
>between the long insulators, the guys were broken up with the usual johnny
>balls.
>
>The new site has been in use for nearly twenty years and I have only heard
>the transmitter hiccup once during a storm and that was probably due to a
>direct or nearly direct strike.  No popping noises have ever been heard at
>the new site.  The sheer length of the insulators prevents the guy insulator
>arcing problem.  Since that time, I have added long insulators to the guys
>at two other AM sites in the area, with similar success.