On the unit I had years ago,
The selsyn on the tower
was driven by a small chain from a gear sprocket
on the rotor assembly
That selsyn drove another selsyn that is in the shack on the control box
basically the selsyn are dc motors
the one in the shack has a pointer on it
that is on a dial face showing headings (bearings of the compass)
The unit on the tower drives the one in the shack
(the unit on the tower becomes a small generator)
The down side was chain slippage
I would recommend a more modern approach
either a wireless GPS Compass module around an Ardunio or Rasperry Pi box
with wifi transmitter/receiver
Which is available off the shelf from a place called Ham Station if my
memory on it is any good
I once built a ring of very small relays
and placed a very small but powerful button magnet on the mast
when the magnet was perpendicular to the relay it closed the normally open
contacts
and the relay contacts were wired to the shack panel to illuminate a small
LED
on a rose Compass diagram showing my present beam heading
It was visually appealing in the shack
Cheers!
Steve
KG5VK
http://sdxa.blogspot.com/
KG5VK Blog
http://www.KG5VK.com
My Ham Radio Friends
On Thu, Nov 15, 2018 at 11:04 PM Martin Sole <hs0zed@gmail.com> wrote:
> 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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