Yaesu Rotors

[Chris Pedder]

Don Moman wrote:
> 
> The KLM log is rated at 12 sq ft and weighs 100 lbs (7.2-10-30version).
> 
> A friend here locally had a similar problem with his G1000 rotor on a
> Sommer beam( quite large, has coverage from 7 to 30 mhz) and it failed
> very soon in its' career. Well within the wind spec too, but possibly not
> within the "flywheel" spec. Why bother to specify a wind area when it's
> such a vague spec anyway?  Anyway it was full of parts that rattled -
> gear parts not ball bearings.  He replaced it with a Emotator (not sure
> of the number) and it has behaved fine since.
> 

As I remember, and unfortunately I do not have the relevant document to hand, Emoto 
are one of the few (only?) rotor manufacturers who, in addition to specifying wind 
area for their products, also specify 'Gd^2'. I take this to be moment of inertia and 
this would be what I would wish to consider, rather than the product of mass and 
boom-length.

I should perhaps relate my experiences with a Daiwa MR750PE, which was the 
'four-motor' rotor from that company. I used it to turn a 20m PV-4 which in addition 
to having a 42 foot boom was not of lightweight construction. I had made no attempt to 
balance the antenna dynamically as suggested later, in his book, by W6QHS. Initially 
the clamps (surprise) slipped so I tightened them. When they slipped again I drilled a 
pin through, albeit a small one. When the pin broke I put a couple of 8mm stainless 
steel machine screws through. When, shortly after the antenna would not turn, I took 
the rotor out and as I opened it up, large pieces of metal started falling out. The 
(cast?) frame around which the rotor was built had been destroyed. What a heap of junk 
that rotator was.

It seems to me that in a well designed amateur station the weakest link is going to be 
the rotor. What a pity it is that the supply of Prop-pitch motors is not sufficient to 
go around.

73,

Chris
---------------------------------------
Chris Pedder	G3VBL/8P9EM
E-mail		g3vbl@netcomuk.co.uk
AX25-mail	g3vbl@gb7bnm.#45.gbr.eu
DX-Cluster	g3vbl > gb7dxd
---------------------------------------