[TowerTalk] RE : Mast for rotator at bottom of tower?

K8RI on Tower talk k8ri-tower at charter.net
Mon Jun 12 20:56:18 EDT 2006

> Jos,
> I used a brand new GS-065 bearing on top of a small tower to hold the 6m
> long steel mast and a 5-element 20m yagi at 12m, I used the rotator 
> sitting
> at the 6m level for rotation only.
> Weight of mast, antenna and cable was about 90kg.
> After about a year I took the whole system down as I built a bigger tower.
> When I turned the thrust bearing by hand it was a different feel of 
> turning
> then on the beginning, a bit sticky.
> When I dismantled it I found no grease at all anymore and already heavy 
> worn
> racings by the balls.
> On the new tower I use a TB3 bearing, much better, also using a 
> lubrication

After 4 to 5 years the TB-3 at the top of my tower is worn so badly the top 
race sets down flat against the bolt flange. OTOH that bearing was badly 
overloaded for side thrust. This has bound the system up to the point where 
I'm afraid the rotator has failed.  I won't know until I get it down.  I 
already have the tribander setting on top of the tower and held in place 
with "C-clamps".  Now I have to lower the rest so I can work on the 6-meter 
beam and remove the 144/440 arrays.  When back up I'll only have the 
tribander at the top of the tower and the 28'10" long 7L 6-meter beam 15 
feet above that. I figure removing the 144 and 440 arrays will cut that side 
forces on that TB-3 about in half.  (I do have one spare that I can install)

Now all I need to do is get one of my neighbors to pull on the rope to the 
gin pole.

> fitting with it which was already prepared for.

> Perhaps your system is not that heavy, but check the presence of grease
> regularly!

Make sure the beraring is designed to be lubricated.  Some are supposed to 
be left dry.

Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
> 73
> Peter, DF3KV
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of hermans
> Sent: Dienstag, 13. Juni 2006 00:18
> To: 'marc wullaert'; towertalk at contesting.com; 'Bill Turner'
> Subject: [TowerTalk] RE : Mast for rotator at bottom of tower?
> Bill Marc,
> I dont agree completely Marc, as far as I can admit that the Yeasu 2800 
> has
> been constructed the same way as the G-2000RC who is an older version with
> AC motor.
> My rotor is bolted on a removeable and calibrated platform at a hight of 5
> meter. ( Tell you why later ).
> I agree that a steel mast is quite heavy to be supported continously by 
> the
> sole motor ( Max dead weight 250 Kg or 550 lbs max momentary vertical 
> weight
> 800 Kg or 1760 lbs).
> But one can, as I, use a thrust bearing near the top. ( Yeasu GS-065 ) max
> diameter 65 mm and clamped with 8 bolts. I inserted even steel straps as 
> not
> to tighten de bolts on the mast itself.
> Further I dont use a steel mast, but aluminium, 50 mm diam. The first and
> the last section are 5 mm thick, the others only 3 mm thick.
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