[TowerTalk] questions about lightning suppressors

[Dick Green WC1M]

I'm a little confused about lightning suppressor theory.

 

Many of us have installed lightning suppressors from Polyphaser, ICE, K5FD,
etc. to protect control lines running from towers to the shack.  The
Polyphaser units contain MOVs that turn on at 82V. ICE offers two MOV
voltage levels, 50V and 20V.  K5FD offers three voltage levels: 65V
(standard), 35V and 17V. I have the Polyphaser and K5FD standard units in my
suppressor network. 

 

So, if components in a control box are connected to these suppressors, the
voltage on the pins can rise as high as 65V-82V with respect to ground
before the suppressor starts to do its job. Some bipolar transistors can
take that kind of voltage but many FETs and ICs can't. While the suppressors
probably keep things from melting and vaporizing, isn't it probable that
semiconductors attached to the line will be damaged?

 

I ask because we took a massive lightning hit here about three weeks ago
that damaged at least a dozen boxes in my shack. I've got an extensive
ground system and suppressor network. The only way I can explain some of the
damage is that the suppressors allowed the voltage to rise too high for the
semiconductors connected directly to the control lines. Does this make
sense?

 

I'll post a complete report on the damage, which was extensive, my theory on
the path taken by the surge(s) and the recovery when I get a chance. Too
busy fixing things right now.

 

73, Dick WC1M