This is part 3 of the description of my hex beam and accessible rotor. As I
said at the end of part 2, I already had a Ham IV rotor from the 1980s. At
that time, I had a custom synthetic speech board that spoke a three digit
number to indicate the beam heading. A push button was added on the front of
the control box just under the brake button. That button can be pushed with
the thumb while other fingers operate the brake and clockwise or counter
clockwise buttons. But, unfortunately, the external aluminum box with the
speech circuit was lost in one of my many moves.
Prior to the Ham IV, I had a few CDR rotors and before that an Alliance
Tenna-rotor. These were very light duty rotors designed for TV antennas but
work quite well for VHF and UHF beams. Both had either a large knob with a
tactile line on it or had a large arrow for the knob. Spin the knob to the
desired heading and he indicator moved in discrete "ker-chunks" until the
antenna heading matched the direction of the knob. These were great for
blind operators.
With all that as background and also considering that I had not used any
kind of rotor at all since 1990, I set out to see what was new for those of
us who can't see the rotor indicator. I found some references to rotors for
blind hams in Norm's Rotor Service and on Handi-hams. I also read about
several list members taking the glass cover off the indicator on Yeasu
rotors and using them successfully. But, I also found a lot of references to
computer control and driving the rotor control from logging programs. Since
I was trying to catch up on 25 years of missed experience with the technical
progress of accessible rotors, and rotors in general for that matter, I
became very interested in the PC control.
I found Easy-Rotor-Control at http://easy-rotor-control.com/ in Germany.
They have computer interface boards for over 90 rotors, including my old Ham
IV. The rotor control is available in RS232 or USB. Some rotors require
additional interface boards but they are available on the same website. The
Easy Rotor Control, called ERC, is only available in kit form. The USB
version I bought cost 79 Euros. It can be installed inside the rotor control
box or in an external box if there isn't enough room inside the rotor box.
The kit building isn't very complicated. It's 3 relays, some integrated
circuit chips, and a few discrete components. Although I built many kits
before losing my sight, I am not a printed circuit kit builder any more. I
had help from a local ham who built the kit and installed it in my rotor
control box. He said it only took a couple of hours and most of that was
drilling holes in the Ham IV control box to mount the ERC and allow access
to the USB and power connectors. The ERC does require a source of 12 VDC
which isn't available in my rotor so I connect it to my shack 12 Volt
supply. Basically, except for the mounting screws, the only connection to
the rotor controls are wires to the brake, clockwise, and counter-clockwise
buttons and to the feedback wires from the rotor that indicate its
direction.
With the ERC installed and connected by USB to a PC, the next step was
calibration. Again, sighted help was necessary for this part. Calibration
involves moving the rotor to certain headings as requested by the software.
It records the rotor feedback value for every 30 degrees of rotation. Once
calibrated, the rotor can then be controlled from the PC. Using
Easy-Rotor-Control's "Rotor-Control" software, the user can enter an antenna
heading in an edit box and press enter on the "go" button and the rotor will
move to that heading. There is also a place on the screen where it displays
the current heading. It requires using the Jaws curser to find it or reading
the entire screen but a Jaws script could be written to read that screen
area. I didn't do so because I don't use the ERC software, only the
hardware.
I wanted more than manual rotor control from my PC. I wanted an automatic
interface with my logging software. I use ACLog. It was already interfaced
with my Elecraft KX3 for reading band, mode, and frequency and placing that
in the log. It also runs a DX spotting window with voice announcement of any
needed countries that are spotted. after moving to the DX spot window and
arrowing down to the station I want to work, pressing enter will place that
station's call sign in the log and will move the KX3 to the band, mode, and
frequency where the station was spotted. This is all very helpful in chasing
that needed DX entity. But, the beam still needs to be moved to point to the
correct heading. By the way, ACLog does calculate the beam heading and
display it in the DX spot window, along with the distance to that station.
However, the formatting is inconvenient for reading by Jaws and the miles
and beam heading are read as a single string of numbers.
So going back to more internet research, I found "PST Rotator software for
antenna rotators" at http://www.qsl.net/yo3dmu/index_Page346.htm
This software costs 20 Euros to license. It creates a bridge between logging
programs and computerized rotor controls. If your rotor already has a PC
interface, all you really need is this package to interface your logging
software with your rotor. In my case, I first had to add PC control to the
old Ham IV but many newer rotors already have a computer interface. The PST
Rotator software interfaces with many, many logging packages, including
ACLog which, as stated earlier, is what I use. Once PST Rotator is
configured to know what logger and what rotor interface is being used,
everything becomes automatic. When a call sign is entered in the logging
package (either manually or because it was selected in the DX spot window,
PST Rotator calculates the antenna heading and moves the antenna to that
heading. Although you seldom need to go to it, if you switch over to the PST
Rotator window, you can select short path or long path and you can enter
headings manually in an edit box. Also, the author has a feature for blind
operators. If you press control+b, the current beam heading is read aloud
through Microsoft SAPI speech. This is helpful if you want to "watch" the
beam turn by repeated pressing of control+b.
PST Rotator is even further automated if you wish to take advantage of the
features. It can be configured to automatically start the program when your
logging software is started and to exit when your logging software is
closed.
So far, I'm very pleased with the combination of ACLog, the old Ham IV,
Easy-Rotor-Control, and PST Rotator. The only issue I have is that I haven't
managed to calibrate the counterclockwise end stop correctly. I can't turn
the beam further North than 5 degrees and if something between 0 and 5 is
requested from the software, the rotor continues to try to turn past it's
endpoint. This could cause damage so I have to be careful and listen to the
ERC relays. If they don't drop out, I have to override any software
requested heading between 0 and 5 with something 6 or higher. I'm sure this
can be resolved. I just haven't found the magic incantation yet.
Finally, there are probably way easier ways of doing what I did but, for me,
figuring something like this out is a big part of the fun of ham radio.
Integration of Hardware systems with software systems and seeking
accessibility can be really fun. In cases like this, Google is your friend.
There's an amazing amount of information on the internet if one just takes
the time to look and to sort out the junk from the treasures.
Have fun and good DX.
73, Jim, KY2D
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