[TowerTalk] Telrex rotator

[Patrick Greenlee]

Steve, I went to a USAF 8 month electronics school 1963-64 for a Link 
C-11 c instrument flying trainer and we spent plenty of time on 
autosyns, selsyns and their kin. What is amazing is that after over 50 
years I remember that stuff.

Carry on, gentleman.

Patrick        NJ5G

On 11/16/2018 6:41 AM, Steve Lott wrote:
> Yes as Patrick pointed out I meant AC
>
> not enough Coffee before getting on the computer :)
>
> cheers!
> Steve
> KG5VK
>
> http://sdxa.blogspot.com/
> KG5VK Blog
>
> http://www.KG5VK.com
> My Ham Radio Friends
>
>
>
> On Fri, Nov 16, 2018 at 6:34 AM john at kk9a.com <john at kk9a.com> wrote:
>
>> I had one of these rotators and I never had an issue which was a big step
>> up from the Hy-Gain HDR-300 that it replaced. Sadly the resale value is
>> poor and I almost gave it away when I switched to using prop pitch
>> rotators.
>>
>> If it were me, I would replace the selsyn with a potentiometer and then
>> almost any control box would read the direction, especially a Green Heron
>> where you could calibrate the indication. The remaining issue would be
>> supplying 120v to the motor. This could be done with relays activated by
>> the low voltage control box or perhaps W2FU has a better solution.
>>
>> John KK9A
>>
>>
>>
>> From:   Martin Sole hs0zed
>> Date:   Fri, 16 Nov 2018 12:04:18 +0700
>>
>>
>> Hi,
>>
>> I'm restoring a Telrex A3695RISX rotator. It's quite a monster but if I
>> can figure out a way to use it I think it's unlikely I would ever need
>> anything bigger, 1/3hp reversible AC motor, dual worm reduction gearbox,
>> chain drive to 3" output shaft and it weighs about 125 lbs, around 57kg.
>>
>> I have no control box which poses a small problem. Wiring to the motor is
>> straightforward enough though I think the limit switch arrangement could
>> be handled better.
>>
>> It uses a selsyn for position indicating. In this case actually a General
>> Electric Selsyn Control Transformer 2J161. This is marked 57.5-57.5 V
>> 400CY. The device is working in that I can get the three outputs from the
>> stator winding when I excite the rotor winding, all three stator outputs
>> rise and fall with rotation so I'm pretty sure its good.
>>
>> The problem is what to do at the other end. Without a matching selsyn, not
>> something I expect to ever turn up around here, I am wondering how I might
>> be able to take the selsyn outputs and interpret them by some other means.
>> My understanding is the 3 stator outputs are AC voltages varying in
>> amplitude and with a fixed phase relationship in order to produce an
>> unambiguous value related to absolute position. I'm not 100% on this yet
>> though. They are in a delta configuration though so I'm thinking anything
>> I do first needs to make them Y configured
>>
>> What are my options?
>>
>> I had thought about an I2C compass module but that will entail placing
>> some other conversion hardware at the rotator to convert to something like
>> RS422. Any other thoughts. Just looking for ideas to think of what might
>> work well enough. Ideally keeping the selsyn as it's all purpose built
>> around that.
>>
>> Martin, HS0ZED
>>
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