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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