[TowerTalk] Fwd: TIC-Ring Question

[Grant Saviers]

Resent w/o pictures per K7LXC request, contact me off list if wanted.


-------- Forwarded Message --------
Subject: Re: [TowerTalk] TIC-Ring Question
Date: Fri, 11 Nov 2022 11:10:15 -0800
From: Grant Saviers <grants2 at pacbell.net>
To: towertalk at contesting.com

Hi Dave,

Re limit switches, I had to fabricate limit switches for the K0XG rings 
on my Rohn 65 tower.  7 rings.  The mount has the switches on the tower 
leg, and the ring uses a 3x3x1/8 6061 angle plate and a delrin block to 
actuate the IP65 Honeywell microswitches.  I don't recall why I used 
IP65 vs IP67.

I was willing to sacrifice about 30 degrees of due south pointing to not 
have to have overtravel in the switch assembly, since each switch has 
some deadband.  That simplified things a bit, with hardly any DX (except 
HC8!) in due south from WWA.

It took a bit of cut and try to get the distance from switch roller to 
actuator plate trip point correct by modifying the thickness of the 
plastic block or the offset from the tower leg (I think what is shown in 
the pictures).  One constraint is the actuating block has to rotate 
without interference.

The switches are Honeywell IP65 from the picture.  They are on the 
underside of the mounting plate.  I think I replaced one (of 14) in the 
past 6 years, but it measured ok.  The switches go to a j-box with 
diodes so the ring can be reversed off limit.  One diode failure also. 
My plan is limit switches are last resort if the RT21 programmed limits 
are off.

I did have to change the ring centering cam rollers from factory to get 
the ring and pinion gears to fully engage and haven't observed any 
jumps, but that is not proof it hasn't happened a small amount.  The top 
ring @140ft is 3L 48ft boom 40m full size.

What I learned:

Use much larger diodes - the K0XG motors are 180v DC PWM driven and it 
is difficult to find 1kv 10a diodes that are not stud mounted so I did 
the best I could.  Also, use TVS protection since it might be full motor 
voltage/current being interrupted.

Put a high value resistor across the switch contacts so bad switch, 
wiring, or bad diode can be analyzed from the shack, if one can't 
reverse out of a limit.

Clearly mark the inside of the j-box with wiring and part orientation 
and photograph it.  Most tower climbers aren't EE's.

Waterproof plastic j-boxes aren't, so always have a smaller than bug 
size drain hole at the low point.  Maybe 50" of rain here per year. ;( 
Use 6x6 rather than 4x4 j-boxes.

I like the idea of a back-up magnetic azimuth sensor, looked a bit at 
them but wondered how they would work among all the steel and RF.

73,

Grant KZ1W



On 11/11/2022 10:11, Leeson wrote:
> I've been using a TIC ring rotator here on a big 7el 10m Yagi for the 
> past 20 years with good success, but it has a couple of well-known 
> unresolved problems: In the high winds we have on our hilltop (147 mi/h 
> 3s gust measured), it can jump a tooth on the motor or pot gear, which 
> eventually makes the direction indicator pot totally out of sync, or 
> even damages it. Since the ring rotor doesn't have physical limit 
> switches, that has permitted over-rotation that parts the coax.
> 
> Re direction indication, has anyone had any success with alternatives 
> such as magnetic or microswitch gear tooth counters? Or a simple compass 
> module with output that a Green Heron RT-21 can read (0-5 volts)? See 
> G6EJD, KJ4JJH, K3NG. I'd like to have direction indication that mounts 
> directly at the ring or antenna boom itself, rather than through a 
> coupled gear. and it should work at zero speed.
> 
> Second, has anyone had success with adding waterproof (IP67) limit 
> switches? Honeywell, Omron, IP67 microswitches or cheaper imports? If a 
> magnetic gear tooth sensor is used, what kind of spacing precision is 
> required? With 360 teeth, the 1° precision should be plenty for HF.
> 
> I am aware of modifications and updates (e.g., N1CX) that may help 
> prevent gear tooth skipping, but I want something bullet-proof that 
> really gives me full confidence. Even a partial failure in a contest can 
> compromise an otherwise winning effort; in our big HC8 station, we gave 
> up on rotators and went with multiple antennas per band. But for my less 
> complex setup here at home, I intend to try to resolve both of these 
> problems when the weather permits, and am interested in hearing the 
> experiences of list folks.
> 
> BTW, I resolved the climb-over issue with a small 3-rung steel ladder 
> mounted below it on the tower face. And if the limit switches work out, 
> I'll add them to my prop pitches, as well.
> 
> Thanks, Dave W6NL/HC8L
> _______________________________________________
> 
> 
> 
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk