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[TowerTalk] OLD Hy-Gain Rotator (long!)

To: <>
Subject: [TowerTalk] OLD Hy-Gain Rotator (long!)
From: (Steve Maki)
Date: Sat, 14 Apr 2001 01:20:14 -0400
<> wrote:

>I have an older Hy-Gain antenna rotator that I bought used
>from AES back in 1988. It's a model "RBX-5" and I was
>wondering if anyone else is using one of these and has any
>information on them?
>I'm guessing that the unit was a commercial-type rotator
>and it is very large & heavy. It's about 18" x 24" x 14"
>high and weighs around 250 lbs, I'm guessing. It uses a
>1/3 HP motor which is connected to a worm-type gear
>box, the output of which is further reduced in speed via a
>couple of sprockets connected w/ 50 pitch chain. The
>output shaft is about 1-1/4" dia. solid steel and I use 50
>pitch chain to connect it to the antenna mast.
>The unit originally came with selsyn motors for use as a
>direction-indicating system. My particular unit had a pair
>of 115 volt, 400 Hz. selsyn motors. The distance from
>the rotator to the control box in the shack is about 250'
>and because of that, I was never able to keep the selsyns
>in calibration. I tried using larger-gauge but that didn't do
>any good. I was told that the reason why they wouldn't
>stay in calibration was because they were 400 Hz units
>and I was trying to operate them on 60 Hz power.
>I had originally used the rotator to turn a KLM 40M-4
>with the H.D. boom and also a Hy-Gain 204BA, which
>was mounted about 8-1/2' above it on the same mast. I
>put a long piece of reflective tape on the boom of the KLM
>antenna in front of the boom to mast plate. I would then
>get a spot light and shine it up at the antenna at night, to
>see where the antennas were pointed!
>This got very tiring, to say the least. At my former job, I
>noticed that there were a number of NAMCO brand pro-
>grammable limit switches that were used for indicating the
>position of the 7th axis of robots that moved along a gantry.
>These units had a 3-digit readout and I thought that maybe
>I could use convert one of them for use as a really precise
>system of direction indication for my big Hy-Gain rotator.
>I found that these Namco units employed a gear box with
>a reduction ratio of something like 29:1 to operate a small
>resolver motor, which was used to provide input to the
>controller box. I knew that this 29:1 ratio would be of no
>use to me, as I needed a 1:1 ratio for my application. I
>took the gear box apart and hooked the resolver up to
>the Namco unit.
>I discovered that one revolution of the resolver motor would allow the Namco
>unit to count  from zero through whatever number was chosen for the range that
>it was to count through. I then set the "scale" (the number range from 0 to
>the highest number that would be indicated) to 359 and
>the unit counted up from 0 to 359 with one full revolution
>of the resolver motor!
>So I went up the tower and removed the 400 Hz selsyn
>motor and removed the small bevel gear from it. I then
>mounted the bevel gear on the shaft of the resolver mo-
>tor and bought some special 3-pair individually-shielded
>wire to connect it to the controller box. It worked very
>nicely. I finally had a nice digital read-out of the antenna
>direction. But my new system caused another problem.
>The original Hy-Gain control box used a 3-pole double
>throw toggle switch for the CW - CCW movement and
>I no longer needed the control box but I needed a way of
>moving the antenna CW & CCW.  So I bought some
>small Grayhill pushbutton switches and mounted them and
>a spst toggle switch to a small piece of circuit board mater-
>ial and mounted it alongside my antenna tuner. I used the
>toggle switch to turn the AC power on & off to the Namco
>controller box and also used it to energize a control relay
>down in my basement, where the 110 VAC supply wires
>went out to the rotator (I had a relay box up by the rotator with 2 - 3 pole,
>double throw relays, for CW & CCW rotation).
>I was wondering if anyone else is using one of these old
>Hy-Gain rotators, when they were made and what the
>original cost of them was? I tried to find out from Telex
>Hy-Gain right after I acquired the unit in 1988 but the
>person I spoke with told me that the unit was so old,
>they didn't have any information on it at all. They sent me
>some information on their model "3501DA" rotator, which
>looks just like mine, except that they had equipped it with
>a fancy control box, complete with a digital read-out and
>all the solid-state electronics that went with it. The picture
>of the rotator itself looked exactly the same as my unit.
>Anyway, if anyone has any info on the Hy-Gain RBX-5
>and would like to share it with me, I'd appreciate it!  Good
>DX & 73 de Brad

This rotator sounds suspiciously like the old Telrex
models - basically a reversable AC motor driving a
double worm gear reduction unit with chain drive to
the mast.

I also junked the 400 hz selsyns and limit switches
on mine, but took a different approach for the indicator.

After noting the pile of old Ham-4 rotators in my garage,
I decided to make use of one of them for my indicator.

It is a simple job to remove the Ham-4 gears, mount the
shell below the final chain sprocket, extend the mast down
to the Ham-4, and then use a modified Ham-4 control box to
control the whole mess.

The Telrex (or Hygain in your case) is then used only
for brute rotating duty, and the Ham-4 shell is used for
position feedback and limit switch duty.

Steve Maki

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