[PVRCNC] [smithchart] Rotator Repairs

[N4CW at aol.com]

Yesterday, Bill, K4CIA, and I went to KD4NMI's place with a Ham-III  
rotator that I'd salvaged from a ham's estate. We knew he did rotator repairs  
after a tip from Bob, K4HA (and a 'tip o' the hat to you, sir!').
It didn't work when I tested it, and the Ohmmeter test of the terminals  
indicated a bad limit switch...plus, the rotator hummed real loud when the 
brake  release was enabled...I mean REAL loud!
 
I had called Richard earlier and he said to come over, that his "shop" was  
open 9AM to 9PM. So we went.
His place is just off I-540 and Rte 64 in Knightdale, on the south side of  
the intersection -- real easy to get to. Anyway, he put the rotator on a  
home-made jig on his bench and took the housing (and bearings) off to expose 
the  "innards". While doing that, he discovered the ring gear was 
cracked/broken --  no problem, he had spares! He had a control box set up with various 
plugs to  accomodate the type associated with any particular HAM-series 
roatator. He  plugged it in and confirmed the loud humming of the brake and 
that it would turn  in only one direction. It was a smoky exploration!!! That 
led to the discovery  that one of the leads to the brake was chafed and 
shorting to the frame due to  improper lead dressing by somebody who'd previously 
had the rotator apart. (It  was also noted that a nylon spacer had been 
omitted when the rotator was  reassembled.)
That was repaired in short order, but we had another problem, this time  
with direction indication. That problem's solution was a bit involved and  
eventually resolved. Meanwhile, the rheostat/direction indicator pot was tes
ted,  cleaned, lubricated with graphite, re-soldered, and tested again. The 
limit  switches were checked and one needed to be "formed" so it would make a 
good  wiping contact when closed.
 
It was ready to reassemble. But first, the two housing bells and bearings  
were cleaned, the bearing raceways polished, the motor gears cleaned, then, 
as  the unit was reassembled, the gears were lubricated (lithium grease), 
the  raceways greased prior to the bearings being installed, the bearings 
installed,  then lightly greased on top, and the two halves expertly joined, 
centered  mid-scale/North on the direction meter, and all the bolts put back 
into place.  After a final test to both CW and CCW limits, where the quiet and 
smooth turning  was noted, as well as no "spikes" in the meter reading as 
it traversed from one  direction to the other, it was set back on North and 
ready to go.
 
Same day service, with me watching all the way, and a really reasonable  
cost for parts and labor. Outstanding! That's the Ham-III rotator I'll be  
bringing to the hamfest to sell on Saturday (the other rotator I'm bringing is 
a  Ham-IV...I had thought it was another Ham-III, but closer inspection 
showed  "HAM-4" stamped on the bottom!.
 
Anyway, I thought I'd share my experience with the group. It would have  
cost me at least $30 to ship out-of-state for repairs...plus those other  guys 
are more expensive! 
 
73,
Bert, N4CW
 
 
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