My K2 adventure with antenna static discharge

[N9AUP]

My recently completed K2, #7235, worked FB for two weeks.  One evening, while listening around the bands, I stepped over to my balanced feed tuner to change taps.  What I didn't realize was that a healthy static charge had built up on my vertical linear-loaded dipole.  When I reached for a tap I drew a healthy spark.  That was nearly as unsettling as the snap that erupted from my K2 as one of the PA transistors let go.

With excellent support from Elecraft and the advice of others on this forum, I was able to repair the damage and get my K2 back in order.  In the process, I did hear from a number of people on the forum that it was not uncommon for K2's to be damaged by static discharge.  

Each leg of my balanced feed now sports a 15 Megohm 1 watt carbon resistor anchored to a grounded braid strap.  I haven't noticed any change in performance and there is absolutely no evidence of a static build-up.

For whatever it's worth. . .

George
N9AUP

[picmaster]

George,

Thanks for reminding that we should keep those sweet K2s alive and in good
health. Typically, if you have your antenna attached to the K2 ANT connector,
the DC path through R67 & R68 (RF Board) won't allow a static built-up. But as
you already shared, the question is what happens when the antenna is
reconnected (via feeders, tuners, switches) - your solution is good enough.
Also miniature neon lamps could be used for the same purpose - I think there
are models that have breakdown voltage less than 90V...

Btw, you don't have to use such a big resistor for static discharge - any value
that's at least 10 times bigger than the system impedance will work
(e.g. 500+ ohms).

73,
Nikolay (LZ1NRD)

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[N9AUP]

For reasons of convenience, the resistors are mounted on the antenna side of the tuner.  Since I'm tuning from 3.5 mHz through 15 mHz into a roughly 10.5 meter linear loaded dipole, the impedance in some instances is quite high, thus the large value of resistors.

regards,

George