I've posted this before but if you have the "small" prop pitch motor and
it's bevel gear output, I found a good commercial gear that fits exactly. It
says "Martin 35-36" on it. A good industrial supply house should be able to
get it for you.Very reasonable price - $10-15. The only problem with it is
that it comes bored for a 1/2 " shaft - much too large for most selsyns. A
local machine shop guy agreed to plug the hole and mount the gear on my
selsyn shaft for bottle of Royal Crown- fair enough and he did a great job
(before he got to the bottle).
Gene / W2LU
----- Original Message -----
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
To: <towertalk@contesting.com>
Sent: Friday, September 03, 2010 1:07 PM
Subject: Re: [TowerTalk] Antenna Rotor Speed
>
>
> On 9/3/2010 11:25 AM, Jim Hargrave wrote:
>> Hi Peter,
>>
>> Looking at your pictures, it seems that you should be able to add a
>> sprocket
>> to the chain drive in your limit switch area.
>> I had to do a similar thing to mine a few years back.
>>
>> My original controller used selsyns until one was creamed by a voltage
>> surge
>> caused by a huge static burst in a storm.
>> I could not find a matching selsyn at the time so I went to the
>> conventional
>> controller approach. I now use a modified CDE controller with a RotorEZ
>> controller interface to control relays mounted at the base of the tower.
>> The
>> RotorEZ controller module provides excellent interface to my Logger32
>> logging program.
>>
>> My Prop Pitch still has the taper gear attached to the top of the
>> gearbox. I
>> hand cut a matching gear to drive a 500 ohm potentiometer. I made this
>> from
>> 1/4 in. phenolic flat stock. I had an aluminum gear (Home brewed) that
>> had
>> the same number of teeth as the prop pitch Gearbox to drive the selsyn,
>> but
>> when I cut the phenolic gear I increased the size so I could get a
>> rotation
>> of 330 degrees on the potentiometer to 360 degrees on the rotor. I then
>> mounted the pot to the gear using a spring arm in case of overrun or
>> limit
>> switch failure. This has worked for several years without any problems.
> Just as a suggestion, if using a pot like this, why not use a 3 turn or
> even 10- turn and calibrate a section to use for the 1 or 1 1/2 turns
> made by the rotator. The old Prosistel PST-61 used this scheme and it
> works very well. With the rotator only able to make 1 to 1 1/2 turns and
> using 1 to 1 1/2 turns on a 3 turn or 10 turn pot gives a bit of safety
> margin.
>
> For gears in the past I've used bicycle racing gears (Chain Ring) and SS
> chain
> Matter a fact I have several spare chin rings and SS chains.
>
>
> 73
>
> Roger (K8RI)
>> Attached is a photo of the Rotor showing the added gear. The Rotor is
>> mounted near the bottom of the tower for easy maintenance. It is the
>> small
>> prop pitch with 24 vdc motor. It rotates a HyGain TH6 (@ 50ft.) and a 14
>> el
>> 2M beam (@ 60ft). This is topped off by a lightening arrester which is a
>> grounded tri-band VHF/UHF Home brewed J-Pole using 1/2& 1 in. copper
>> tubing. The complete antenna cluster rotates.
>>
>> 73's Jim (another one)
>> W5IFP
>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com]On Behalf Of DF3KV
>>> Sent: Friday, September 03, 2010 7:59 AM
>>> To: towertalk@contesting.com
>>> Subject: Re: [TowerTalk] Antenna Rotor Speed
>>>
>>>
>>> Hi Jim,
>>>
>>> My drive motors usually are 3-phase 400V, so I have no problem to use
>>> automated ramping with a cycle inverter now.
>>> But first I need to add an additional position indicator to supply
>>> information to my electronic for that reason and to add point and shoot
>>> features.
>>> At present I only drive a selsyn together with the limit switches.
>>>
>>> http://ic2.pbase.com/g4/91/283791/2/64082622.IWWhlXiA.jpg
>>>
>>> http://ic2.pbase.com/g4/91/283791/2/64082562.ehwDr8mw.jpg
>>>
>>> http://ic2.pbase.com/g6/91/283791/2/68997594.xSfo0AWi.jpg
>>>
>>> 73
>>> Peter, DJ7WW
>>>
>>> -----Original Message-----
>>> From: towertalk-bounces@contesting.com
>>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Thomson
>>> Sent: Freitag, 3. September 2010 13:47
>>> To: towertalk@contesting.com
>>> Subject: [TowerTalk] Antenna Rotor Speed
>>>
>>> Date: Thu, 2 Sep 2010 20:10:38 +0200
>>> From: "DF3KV"<df3kv@t-online.de>
>>> Subject: Re: [TowerTalk] Antenna Rotor Speed
>>>
>>>
>>> I found 40 seconds for one rotation real nice for contesting after I
>>> built
>>> my own rotator.
>>> I turned a christmas tree of 5 element yagis 20-10m + 3L FS on 40m
>>> without
>>> problems, but the stress on the double worm gearbox is quite heavy.
>>> I used finally a 50mm drive shaft to flange to the rotating mast, 25mm
>>> sheared off immediately the first time the rotation stopped.
>>> On my present installation with slew ring drive it takes 90 seconds to
>>> travel 360? which I find a bit too slow.
>>> Higher speeds are no problem for antennas built to survive storms.
>>>
>>> 73
>>> Peter, DJ7WW
>>>
>>> ## PWM is cheap. I bought a small pre-assembled PWM on a PC
>>> board... and it's rated for a max of 30 Vdc @ 50 A CCS. The pot on
>>> the board is removed... and replaced with 1-3 pots..and a switch.
>>> Then you
>>> can switch from slo-med-fast.... and back down again.
>>>
>>> ## The GH box is superb.. with it's ramp up/down and point
>>> and shoot feature.
>>>
>>> later... Jim VE7RF
>>>
>>> _______________________________________________
>>>
>>>
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