Holy Cow, Jim,
Who would ever use a Ham-M, Ham-4, etc. with a 2 inch mast without shimming it
1/32 from the two sides of the fixed bell housing? I thought we learned this
in first term Tower Construction 101 . . .
Stan w7ni@teleport.com
Jim White, K4OJ wrote:
> K9OFG asks:
>
> "So, how about locating the open side of the rotor bell such that the
> set-bolt is opposite, and loosening the u-bolts a bit at a time while
> tightening the set bolt till the set bolt has the mast clamped solidly?
> Seems that would avoid any centering problem"
>
> .......close, but no cigar, as they say here in Tampa........
>
> Especially if you are using a Telex ham series rotor which has built into
> its design, the anticipation of a 2 1/16" (did I get that right, Barry)
> diameter mast. (As opposed to the rotors which use split brackets on the
> top like Create, etc.)
>
> ONLY if the mast is this diameter will the mast NOT rotate eccentrically
> around the center of the rotor housing....in other words...almost never do
> you exactly have this...especially if you use plumbing pipe (a definite no
> no) instead of 2" OD mast.
>
> Why? Since one side which is holding the mast is fixed (the bell housing)
> its position relative to the center rotational axis of the rotor is
> constant.....it is FIXED, the u-bolts only serve to pull the must up
> against it.......and in reality, it does NOT center the mast unless the
> mast is the 2 1/16 OD, ever!
>
> Unfortunately this was learned from the ole school of hard knocks
> /////REALITY//////
>
> Draw yourself a sketch as viewed from above, the housing bell always is in
> the same position relative to the axis of rotation....taking it to the
> extreme, if you were to put in shall we say a 1" OD pipe it would align way
> too far into the vee of the bell.....if you used a 3" pipe it would not go
> far enough into the vee.......either way the end result is a mast which
> rotates eccentrically.
>
> NOW, couple that with the bolt coming in FROM ONE SIDE ONLY on your pointy
> top (part your hair to the side, to make it less noticeable) and at one
> point of the rotor's rotational cycle you are at the "low spot" where the
> mast is the furthest in one direction off center...lets call it
> North....you then tighten your pointy top bolt.
>
> When the rotor turns 180 degrees to the South, the mast will still continue
> to be rotating eccentrically and now it is eccentric favoring the "high
> spot" - and your pointy top bolt is causing all kinds of havoc at rotor
> level because the mast is being forced sideways by the bolt, putting
> leverage on the rotor bell......
>
> Not a pretty sight......
>
> QSL?
>
> 73,
>
> Jim, K4OJ
> k4oj@ij.net
>
> Less than 2 months until Sweepstakes CW, make sure you work me so you will
> not miss the elusive South Floirda multiplier!
>
> Proud member of the Florida Contest Group - visit our website at:
> http://www.4w.com/deemer/fcg.htm
>
> The Florida Contest Group sponsors the Florida QSO Party, check out the FQP
> website@:
> http://home1.gte.net/wd4ahz/fcg/ssqp.htm
>
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