John,
I can only guess from your comment that you have not had any experience with
a prop pitch motor used as a rotator. There are several reasons that one
would use a prop pitch motor.
One was cost, as surplus motors were available at very reasonable prices.
They bring some premium now do to limited availability.
Another reason was power, or Torque. They can handle very heavy loads.
Another reason is size and shape. They fit inside relatively small tower
cross sections, with no projections beyond the tower sides as some of the new
models do. This makes them very ideal for crank-up towers as all is within
the tower envelope.
The electric motors (nom. 24vdc) are held in place with a large castle ring
nut, spin that off and the motor unplugs for easy maintenance. The gear box
removal is on a par with most rotator types.
One of the drawbacks however is direction sensing. That has to be added.
Historically that was done by use of Selsyn tx/rx coupled to the mast. Today
both M2 and Green Heron Engineering provide controllers with pulse counting
direction indication.(K7NV design used with GHE, check out his web site). The
GHE controller has many features and provides ramp up and down which is
useful with large arrays.
I have had the same prop pitch motor in service for nearly 40 years, trouble
free.
summarizing - Power (torque) and Size.
Norm W4QN
==============================================================
Message: 3
From: John Cowan <w0tmm@yahoo.com>
Subject: [TowerTalk] Prop Pitch Motor
To: towertalk@contesting.com
Why would you use a prop pitch motor as opposed to a regular rotor?
John W0TMM
-----------------------------
Message: 4
Subject: Re: [TowerTalk] Prop Pitch Motor
To: w0tmm@yahoo.com, towertalk@contesting.com
wasnt he going to turn some serious snort? After making about 6 trips
up the tower to work on rotors this last year Ive wondered why I didnt
go to them in the first place. A new spid is working great for me know
though.
73 Mark W0NCL
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|