[TowerTalk] Homebrew Yeasu SDX Rotator Computer Interface?

Mon, 28 Feb 2000 12:18:11 -0500

I designed my own interface.  Here is how it works.

I use an MC14469 ic and the heart of the controller.  It is a microprocessor
that accepts serial imput at 4800 baud and responds with two bytes of data.
The data to the mc14469 is done serially via a RS485 port over a twisted
pair between the control box and the computer.  I use this same twisted pair
to control remote coax switches, a tuner and an az/el setup remotely from
the shack.  I can control up to 128 different devices over this twisted pair
from my computer.  The RS485 protocol should operate will up to several
thousand feet over small guage twisted pair.  Currently, I use #22 guage
twisted pair with a shield...

The interface I designed has a a-d converter and a d-a converter.  This way,
I can sense the azimuth and also command the rotational speed.  My software
reads the present azimuth and compares it to the commanded azimuth.  Then
based upon the difference between the two, it commands a rotational speed.
My software initiates the rotation at the slowest speed and then slowly
accelerates the rotor to a maximum of the highest rotational speed.  When
the antenna is within 30 degrees of the commanded heading, the software
begins the decelerate the rotor.  When within 10 degrees the rotor is
operated at the slowest speed.  The software stops the rotor when within 2
degrees of the desired heading.  The interface hardware is mounted on
perfboard inside the control box.  The control box will supply all the
voltages you will need.  One of the pins in the interface connector is also
the analog "speed" input. 

I have a lot of antenna on that rotor and don't want to stress it too much.

By the way, you can easily increase the braking torque of the 800SDX rotor
to equal that of the 1000SDX rotor by adding another set of "sandwich gears"
to the 800 series rotors.  I have done this and it works great.  Call Yaesu
parts and you can order them real cheap...

>From all I can determine, the only difference between the 1000 series and
800 series rotors is the absense of the additional sandwich gear in the 800
series rotor.  Everything else is there in the rotor, including the axle for
the extra sandwich gear.  Take a close look at the back of your owners
manual and you can see what I mean...  Then check the specs and you will see
that only real difference is braking torque and a very slight (several
ounce) difference in weight between the 800 and 1000 series rotor.  I had to
rebuilt the stock 800 rotor after a severe storm broke two axles and the
upper and lower gearbox plates (it also took out half-dozen trees).  

Good luck...

73 de ki6sz

-----Original Message-----
From: Pete Smith [mailto:n4zr@contesting.com]
Sent: Monday, February 28, 2000 11:59 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Homebrew Yeasu SDX Rotator Computer Interface?

At 08:51 AM 2/28/2000 -0800, you wrote:
>
>Just wondering if anyone has done any work on homebrewing a computer
interface
>for the Yeasu SDX rotators.
>
>The interface is right there on a connector in the rotator. There is a
logic
>lead to make it go CW and one to make it go CCW and an analog buffered
output
>for direction readout. A Stamp board would do this level of thing without
much
>effort.
>
>I'm all for Yeasu making money and staying in business but their computer
>interface costs as much as the rotator. It probabily cost them more to put
the
>connector on the board to allow for the interface add on than it would have
>cost them to finish the job and put in the computer interface. <sigh>

The SARTEK controller is probably the best currently available solution --
it has the advantage that it can be moved to your next rotator, since it
uses relays on a daughterboard that lives inside the rotator control box.
See www.hosenose.com for more info.

73,  Pete N4ZR

Don't forget to update your entry in the World Contest Station Database
http://206.102.70.3/search.htm

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