´╗┐Thanks Jim and Frank.  Yes, bonding not grounding. Thanks for the correction. 
I know better but got lazy with the terminology!

73, Bob K6ZZ

Sent from my iPhone

>> On Mar 25, 2020, at 7:44 PM, donov...@starpower.net wrote:
> ´╗┐
> Hi Bob,
> Bonding (not grounding...) coax to the bottom of a tower helps to
> divert lightning currents from the coax shield to the ground system
> at the base of the tower
> Bonding coax to the top of the tower helps to equalize the voltage
> between the coax and the tower face.   This helps to avoid pin holes
> in the coax during a lightning strike.
> Bonding all coax,  control cables and all other external wiring to the
> a ground system  at the entry to your shack forces the voltages on all
> of those those cables to be equal.
> None of this is related to common mode suppression.   That is best
> accomplished by a choke near the feed point of the antenna.
> 73
> Frank
> From: "Bob K6ZZ" <bob.selbr...@gmail.com>
> To: "topband" <topband@contesting.com>
> Sent: Wednesday, March 25, 2020 10:24:11 PM
> Subject: Topband: Feedline Grounding and Feedline Chokes
> Folks,
> I see a lot of references to grounding coaxial feedlines at the top of
> towers, bottom of towers, and at house entry points.  Is this purely for
> static and lightening protection purposes or does it also help mitigate
> Common Mode problems as well?
> If feedlines are well grounded, are chokes still useful for controlling
> Common Modes problems?  I suspect that both can be used, and should be
> used, in a well designed station.
> Are there specific recommendations on the use of chokes on grounded
> feedlines?  Does placement matter?
> Thanks, Bob K6ZZ
> _________________
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