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[Towertalk] HAM-M rotator info

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Subject: [Towertalk] HAM-M rotator info
From: (Bill Coleman)
Date: Fri, 12 Jul 2002 16:04:20 -0400
On 7/12/02 10:26 AM, Rick Stoneking at wrote:

>First, does anybody have the manual/schematics that they could 
>scan/email/mail a copy to me (or know if they are online someplace)?

I have a PDF file of the manual that I obtained on-line. I can no longer 
find the original archive, but send me a private e-mail, and I'll send it 
to you.

>Second, I hooked it up and confirmed that it works, but because it had been 
>up for a while I decided to open it up.  The bearings are dirty and the 
>grease is old and 'gunky' so I want to clean up the bearings and the 
>plastic bearing retainer and put in new grease.  Does anybody have a 
>recommendation on what to use to clean up / remove the old grease form the 
>bearing retainer?  Is there any particular type of grease I should use?

When I restored a Ham-M last year, I just used a small-bladed screwdriver 
to scrape off the old stuff. 

I think what is recommended is a small amount of lithium grease. I 
understand it is easy to use too much grease. Since I'm cheap, I ended up 
using a general purpose grease on mine, and probably used too much as 

>Last, is it possible to use one of the new (newer?) style control boxes ( 
>brake release switch in between the CCW and CW buttons) instead of the 
>small rotator with the switch on the bottom that you move left/right to 

Yes. Note that the Ham-M went through five different versions. Series 1 
and 2 are wired a little differently. Series 3-5 rotators are similar to 
the Ham-II. Note that the Ham-II and Ham-M Series 5 rotators are 
identical, just the control box is different. Seems to me there's a code 
number on the base of the rotator near the terminal strip where you can 
tell which rotator you have.

Ah, here's how you can tell. See: 

One modification I made to my Ham-M (series 5) is to add a break delay. 
There's all kinds of fancy boards you can buy for this, even on the 
Ham-II,etc style boxes.

Mine was simpler. I have a sensitive DPDT DC relay, A couple of diodes, a 
large electrolytic capacitor, and a couple of resistors.

The diodes go from each motor winding to the capacitor. Basically, this 
forms a DC supply whenever the motor is engaged in either direction. The 
resistors and relay are place across the capacitor. So, whenever you move 
the rotator, the relay immediately closes, and it take several seconds to 
discharge the capacitor and the relay to open when motion stops.

The relay contacts are set up across the AC switches for the 
instrumentation and brake/motor supplies. So, you close these switches 
with the left/right lever, but they only open when the relay opens. This 
gives more than enough time for the antenna to coast to a stop before 
engaging the brake.

>Thanks to all who respond.

Bill Coleman, AA4LR, PP-ASEL        Mail:
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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