[TowerTalk] Prop Pitch Indicator

[Stan Stockton]

Roger,

Selsyns work well if they are mounted with a positive connection to 
matching 1-1 gears.  I know that W3LPL has had a bunch of them in 
operation that have worked well for him.  Some have had success with a 
pulley on the selsyn shaft the same diameter as the mast and clamping a 
small aircraft cable around the mast.

Other alternatives include setting up a 10 turn low resistance pot with 
a 8-1 ratio between the pot and the mast so you have an extra turn on 
either end.  Then you can have the same kind of setup you would see on a 
Ham M type rotator using a meter.

I have had both and have had some problems with both - not because of 
the technology but the implementation.  Currently have two of them that 
need attention.

I believe the best solution is to buy a Green Heron Engineering/K7NV 
control box.  Their indicator system uses a stationary reed switch and a 
magnet that is on a piece that is mounted to the bottom of the motor 
shaft.  You set the gear reduction ratio in the rotator box - 9576-1 for 
a small prop pitch - and as it spins it will count turns and give you a 
very accurate digital readout.  The point and shoot knob and electronic 
limiting of rotation are other desirable features.  If you have a big 
antenna you can also ramp up the motor, ramp it down, and run it full 
out in between.  The control box is not cheap but in my opinion most 
antennas that are big enough to require a prop pitch are worth spending 
the extra money on that control box if you can afford it.  I have one 
and wish I had two more.

Stan, K5GO


----- Original Message ----- 
From: "Ro Grrr" <rogrrr at hotmail.com>
To: <towertalk at contesting.com>
Sent: Thursday, November 11, 2010 4:55 PM
Subject: [TowerTalk] Prop Pitch Indicator







I have a prop pitch rotor I got from another ham but has no
provisions for direction indication.


I’ve heard about selsyns but I believe they require gearing to couple
to the mast. His setup didn’t have anything like that and I don’t want 
to go
that route, anyway.


How do I sense the direction ? I have thought about wrapping the mast 
with
something like a bar-code indicator as they do for digital readouts for 
CNC
machines but am in the dark there.


Any suggestions ?




Roger


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