[OKDXA] Lightning Protection For Thrust Bearing

[Mark Beckwith]

I had not heard of bypassing the thrust bearing as a lightning damage 
abatement technique.  I believe this kit is sold to solve the common 
problem many hams have where a dirty connection between the mast and the 
tower is a source of rectification/mixing/intermod that makes it hard to 
copy DX stations.  I think what really matters is shorting across any 
pseudo-diode that might be present (i.e. dirt, grease, corrosion).  I 
don't think it matters how you do it as long as one end is attached to 
the mast and the other end is attached to the tower.  I'm guessing that 
would also short out static buildup. If it was me (I have done this once 
or twice by making my own) I would go from the mast close to the top of 
the tower to the tower close to the top of the tower, and do it in a way 
where it didn't mess up when you turned the antenna.  I can see from the 
DX Engineering listing 
<https://www.dxengineering.com/parts/dxe-bbgk-2-25-p>, their design does 
not rely on having this conductor be "as short as possible" since they 
appear to provide enough conductor to go parallel to your coax feedline 
loop.



I think I made mine with muffler clamps and battery cables.  I'm sure 
the DX Engineering one is better.

Come to think of it, a lightning strike would probably also fix any 
rectification/mixing/intermod issue  ;-)

73 - Mark N5OT



On 2021-10-04 6:29 PM, D C _Mac_ Macdonald wrote:
> DX Engineering has a by-pass kit to direct
> a lightning strike from the mast above the
> tower top to a location on a tower leg.  This
> kit shows the thrust bearing on a flat plate
> at the top of the tower.  I have my thrust
> bearing mounted down inside the tower about
> 6 feet to carry the load of the mast & antennas
> with the rotator another 6 feet below that which
> carries no dead weight load at all.  This allows
> for the removal and reinstallation of the rotator
> without disturbing the rest of the antenna systems.
>
> Do I need to have a similar system with a shorter
> cable to tie the mast down to a spot on a tower leg?
> The mast has no direct solid connection to the tower
> other than the tube in which the mast rotates.
>
> I believe I could (if necessary) replace the bearing
> by removing the rotator, detaching the bearing from
> its mounting plate, moving that mount plate down
> through the now free mast bottom, and then the
> thrust bearing itself.
>
> Ideas/suggestions welcome.
>
> 73 - Mac, K2GKK/5
> Since 30 Nov 1953
> Oklahoma City, OK
> USAF (Retired) 61-81
> FAA (Retired) 94-10
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