[TowerTalk] Rotator Question - Repair or Replace

[Grant Saviers]

John,

I agree that SS is further apart from Al than carbon steel on the 
galvanic potentials chart.  That can lead to galvanic corrosion.

However, on several in salt water boats I owned this wa minor on masts 
and fittings always exposed to salt water.  I think using passivated SS 
(most 18-8 fasteners now come that way) and surface prep treatment of 
the aluminum dramatically reduces the problem.

The Yaesu and HyGain housing designs have mostly full coverage over the 
races which should exclude a lot of water. The worst case I've seen was 
a tower layed down which resulted in a lot of water intrusion inside the 
rotator.

Another corrosion preventive is to use grease that has good corrosion 
inhibitors.  Rheolube (forget which) was the original Hygain lube, 
pretty expensive stuff. No now "not necessary" by the current Hygain 
proprietors.  I've been unable to source it in sensible sizes. Rust 
inhibiting greases make great sense in rotators.  Further, a full 
synthetic grease won't separate and dry out as standard oil + filler 
greases do in 5 to 10 years.

Keeping the grease film established between the ball and race is also 
important.  Rotators that aren't moved for long periods end up with ball 
metal on race metal which is when galvanic corrosion and probably worse 
fretting happens.  Regular (weekly?) motion of at least 90 degrees is a 
good idea.  Small oscillations are killers of bearings if they don't get 
a full rotation of the balls regularly to replenish the lubrication film.

It's amazing how long rotators "work" for most hams.  Just don't look 
inside ;) .

Grant KZ1W

On 8/27/2021 04:35, john at kk9a.com wrote:
> Great advice Grant!
> 
> I would just like to add that if you are in a corrosive environment,
> stainless steel and aluminum do not get along.
> 
> John KK9A
> 
> Grant KZ1W wrote:
> 
> My rebuild Yaesu process:
> 
> Clean the races thoroughly. If there are some ball divots in the
> aluminum, use some 180 grit sandpaper to reduce them, perfection isn't
> needed. Replace the bearing balls with stainless ones from McMaster.
> Lubricate with full synthetic TFE loaded SuperLube.  Lightly lube the
> gears also.
> 
> Getting the "timing" correct of the potentiometer vs the gears is
> important.  Hopefully, you marked the cases before separating and didn't
> move the pot.  It's confusing to get aligned if off.
> 
> If the controller pointer o-ring "drive belts" are flabbed out
> (sticky/nfg pointer), my solution was to toss it into the nearest trash
> and buy an RT21 from Green Heron.  Fixing a Yaesu once was enough.
> 
> Yaesu mechanics are worth fixing.
> 
> Grant KZ1W
> 
> 
> 
> 
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