[BC] More thoughts about AM transmitter lightning sensitivity issue

[Mike McCarthy]

You have received some sage advise.  I have a site with a reset macro 
written to allow two resets in a 10 minute period.  If more than two 
occur, it requires a manual reset.  I have found that usually two 
resets won't damage a TX and keeps nuisance calls to a minimum. If 
the fault is that severe, the TX will self protect and survive the 
lone remaining reset. The problems occur when the TX's fault 
protection circuits are disabled and no reset limit employed.

I concur with checking the ball gaps and setting them to the point 
where they don't arc with peak modulation, plus 1/8".  If the towers 
are low impedance, you can get the balls to within 1/8" and still run 
3+ KW.  That should calm down the trips significantly in all but the 
most intense part of the storm.

I would however have the lightning protection aspect of the ground 
system checked by a consultant specializing in ground systems.  While 
you might have the greatest RF ground system, the deeper electrodes 
and associated components driven in 1947 might have issues with 
accumulated electroplating or marginal mechanical connections 
limiting the effectiveness of the overall dissipation network.  I 
have seen sites where ground rods had eroded in a similar manner to 
guy line anchors eroding due to electrolysis.  Those sites were all 
built pre-1960 in good soil and the surface appearance was noted as 
normal/nominal.

Additionally, very old electrodes can also be sitting within a column 
of insulating materials from years of current conduction turning the 
soil into something other than soil.  I recall a story from a phone 
CO which started having increased reports of damage from storms and 
unexplainable issues with hum, DC offset, and a plethora of other 
phenomena. They unearthed the ground system and found it surrounded 
by 6" of crystalline powder.  All the current flow from the CO 
altered the PH of the soil so much that there wasn't anything left to 
give and the ground simply crystallized towards a sand 
composition.  The same was true of the electrical service ground as 
well.  They replaced the system and all was well again.

MM