Yaesu G-450XL Rotator Azimuth Indicator Problem -- W3DHJ

From: Jonesy W3DHJ
Subject: Re: YAESU G-450XL rotator problem
Newsgroups: rec.radio.amateur.antenna
Date: 1999/07/11

>Further up the thread, Jonesy <W3DHJ@the.keyboard> wrote:

>>Back at the end of the June ARRL June VHF contest
>>my YAESU G-450XL rotator went kah-kah.

>>It still rotates ok -- it just doesn't "read out" anymore...

Most of the early-on postings in this thread have fallen off the back of my ng server. But, I wanted to follow up and report back the outcome of my little problem.
It was a 'free spinning' nylon gear on the 1/4" indicator pot shaft.

It was also a wee bit of poor engineering.

I physically parked the beam(s) at due North (which is the halfway swing point in my installation (-- vs. the usual "Point it South" install.)
I scribed/scratched the case and rotator head to provide re-assembly 'guidance'.
I raised and supported the mast, removed the rotator, and brought it down.
On my workbench, on a 'clean' white towel, I disassembled the unit. I could see no 'obvious' problem with the indicator pot and its associated drive gears -- soooo, I attempted to rotate the indicator pot's 1/4" shaft with needle nose pliers.
BINGO! The shaft happily, easily turned -- whilst the gear remained motionless.

Analysis: The pot has a polished shaft with a wee little screwdriver slot in the end.
The "attached" (nylon?) gear merely slips over the shaft and engages a wee little nylon bridge that (at one time) existed across the face of the gear in the shaft slot.
I surmise that either manual or automatic assembly of this gear onto the shaft forced the gear on too far and too hard. It resulted in the wee little nylon bridge getting bungered up to some extent.
In time it simply broke at both ends -- remaining in the unmoving pot shaft's screwdriver slot -- while the nylon gear happily rotated with no effect.

I pulled the gear off the shaft.
Being an AMATEUR RADIO OPERATOR, and a sometimes clever feller, I c a r e f u l l y knurled (gnarled?) the polished shaft with the 'teeth' of an 8" Vise Grip (tm).
Then, I very thoroughly cleaned the shaft and the gear, and applied a little automotive "plastic emblem contact cement" to the shaft and the inside of the gear.
Then I tapped the gear back on.

<addendum -- relying on memory> If I remember, the pot has no mechanical stop. I was Very Wary about rotating it more than one time, either CW or CCW, because I did not know if it was using a brass-to-brass wiper or a flexible wire connection to the movable contact. I believe I guessed (correctly) that the point where I felt what I thought to be the pot wiper running off the end of one arm of the pot resistance and up onto the end of the other arm of the pot resistance was 180 degrees away from "top dead center". So, having already 'locked down' the gearing at due North, I set the pot at 180 degrees from where I "detected" the end of the pot. That-a-way, I was praying that the gears AND the pot were pointing North. Subsequent bench test with the controller confirmed that I had it all figgered out correctly.
</addendum>

I reassembled the housing.
I used jumper wires to lash-up a connection to the control unit and verify full rotation and 'proper' pointing (by the indicator.)

Then it was back up the tower to install it.

I C A N N O T believe that I really did this with only two trips up the tower. There wasn't even a trip down and back up to retrieve a dropped tool or bolt! THAT was a first for me!!

If you have this rotator, you will do this someday, too -- no doubt.

73 es "gud dx"
Jonesy W3DHJ
--
Marvin L. Jones jonz<AT>config.com
Gunnison, Colorado
173 days to go until the Year 2000 -- So what!
539 days to go until the 3rd Millennium of the C.E.