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Re: [TowerTalk] Prop Pitch Motor

To: Tower and HF antenna construction topics. <>
Subject: Re: [TowerTalk] Prop Pitch Motor
From: "Dubovsky, George" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Mon, 15 Mar 2010 08:51:06 -0500
List-post: <">>
It's worth noting that these "modified" pp gearboxes are no longer capable of 
doing the antenna rotation tasks usually asked of prop pitches. They trade off 
torque and braking capability (holding in the wind) for an increase in 
rotational speed. Please don't do this to a pp.


geo - n4ua

-----Original Message-----
[] On Behalf Of
Sent: Monday, March 15, 2010 9:42 AM
Subject: Re: [TowerTalk] Prop Pitch Motor

One of the fellows here mentioned a speed of 20 or 30 seconds for one rev.  
An unmodified prop pitch motor takes almost 2 minutes per rev.
There was a mod published in CQ Magazine back in the 50;s showing how to  
pin one of the planetary stages in the gear box to speed it up. Many users 
did  the mod and as a result, usually ran the motor on less than the rated 
28vdc to  reduce the speed to more like one rpm.
Before you commit to the voltage you might want to see if your unit is  
stock or modified.
Gerald K5GW
In a message dated 3/14/2010 10:20:32 P.M. Central Daylight Time, writes:

Gene, the current draw at startup is a bunch higher than the  running  
current. Sorry, don't know how much higher.

You are  probably ok with the 3 #12 wires but you might want to test it on  
the ground before a final commitment.

As long as the motor starts,  you will be in good shape and the extra  
voltage drop will only help  slow down the start up.

The prop pitch motors were designed for 28VDC  so that is probably a good  
voltage to use. The speed will be  proportional to the voltage so lower 
28  volts will slow them  down a bit. They are already a tad on the slow 
so use  your own  judgement.

Gerald K5GW

In a message dated 3/14/2010  9:58:38 P.M. Central Daylight Time,  writes:

What is  the maximum DC voltage used  successfully/recommended for one of 
the  "small"  PPM's ?   What speed was accomplished and how was the brush  
at that  voltage ?
I 'm building a power supply to put at the base of  the  tower and can 
change the voltage from about 30 to 48 volts in 6 volt   steps. Cable to 
PPM will 
be 100 feet of 3-#12's. I'm figuring about 0.5  ohms  and about a ten amp 
demand  i.e. a 5 volt drop.
Any  suggestions will  be greatly appreciated.
Gene /   W2LU

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