Wednesday, October 5, 2016

Rebuilding a CDR Ham Rotator Model HAM - M

Well I tested the two Ham IV rotators and one definitely works and the other I will use for spares, but I was told by the seller that both were working. One of these rotators I plan to use for my main HF antenna system when I get it up and running. All I'm going to do now is buy some cable and get things ready.

The only problem I came across with the Ham IV rotators were there size and weight they were just too big for my simple scaffold pole with my VHF set up. What I needed was a smaller style TV antenna that would be light enough for the scaffold pole or up in the attic.

The same chap who I had originally bought the rotators off also had a lighter CDR Ham Rotor rotator. He wanted £40 for it and would also supply a spare AR-40 and the control box, the problem was they were not in pristine condition and needed a good service, I'd never attempted servicing a rotator before, but I had the manual and Utube so I thought what the hell , let's give it a go.

Looking at the two rotators I had previously bought, one was just filthy and full of grease and opened up ( by the previous owner) but the bits were all there in a box. The other was together but the cable connections and terminal strip were shot and stuck with rust from being in the outdoors, they needed a good soak in penetration fluid to free them up. The idea being to then test it to see if anything major was needed to be done.

In the meantime I would start on the dismantled AR- 40 rotator and start cleaning it, degreasing and see if I could put it together. Cleaning took me a day of just removing the old grease and polishing it up. The two ball bearing holders were cleaned but it was obvious I would need 50 new ball bearings as the old were pitted and badly rusted.

I decided the terminal strip had really seen better days. I'd tried to fix it with a simple choc block but there was no way the choc bloc was going to sit where the strip was. So I've went on line and found a UK supplier of rotator parts and ordered a new strip which should be with me in the next few days.

You can see in the pictures how bad it is and no wonder some of the screws were not moving, they were so rusted up! But apart from that, everything else just needed a good clean and degrease and I don't think I'll need to replace anything else. The new ball bearings arrived the other day so I've fitted them in their collar and they are sitting ready to be refitted, typically I needed a further 50 ball bearings for the other collar so I had to re-order and am still awaiting there arrival.
The only other problem I have thinking forward is which way up do I fit the collars with the ball bearings, smooth or the marked side? I think the smooth side should be facing up when located back in the bell end of the rotator like this picture which I found on the web, and if logic dictates this feels right.
Which would then mean they end up like the next picture and although it isn't a CDR Ham, I think most designs would be similar. So the higher facing part of the bearings in the collar actually face downwards.
Until I get the rest of the parts I can't really continue with the restoration so for the moment I'll just have to wait till all parts have arrived. Further updates in my next post!


  1. I am after a new rotary resistor for AR40 at the head end,you mention spares suppliers in UK details would be

  2. Hi John,
    Apologies for the delay in getting back to you. Try I'll also put this in an email to you.