RADIO MODEMS AND SOFTWARE
RTTY on your Atari
by BILL MARQUARDT (N6CBT)
I have been using my Atari 800 as a radio teletype (RTTY) terminal for well over two years with very good results. RTTY is the ham (amateur) radio equivalent of telecommunications networking.
My home is about 50 miles north-east of San Francisco. Several times a week I broadcast back and forth with Larry Johnson (WB6SVS) an Atari ham who lives just south of SF. The farthest I've ever reached directly with my Atari radio system was San Jose, a distance of over 100 miles. And of course there are no phone bills for RTTY. . .
Once you own a well-shielded Atari and a ham radio, your most important piece of equipment is an interface, a sort of "radio modem."
Radio signals are converted by your receiver into audio signals (tones) and fed by cable into the radio modem. The modem translates these tones into data signals that your Atari can understand, and sends it over another cable into the computer. From there, the data can be displayed on the monitor, sent to a printer or saved to a disk or cassette. When you transmit, your keyboard input goes by cable to the interface and is translated into audio tones for the radio.
Antic invited me to review some recent Atari-compatible radio interfaces and software from Kantronics, a Kansas manufacturer that also publishes a $6-yearly newsletter, "Computers and Amateur Radio." Kantronics is at 1202 E. 23rd Street, Lawrence, KS 66044. (913) 842-7745.
The Kantronics Interface II comes with adequate documentation, plus all the cable and connectors you will ever need. It's easy enough to hook up to your Atari and radio, provided that:
1. You can solder well enough to attach the plugs to the cables--or buy the Kantronics software that comes with completed cables.
2. You can understand the meaning of radio jargon such as PTT (Push to Talk).
Like all the other radio modems discussed here, the Interface II requires you to connect a small power supply (that's not included). You can buy an unassembled power pack kit for about $10.
The Interface II performed flawlessly. Its most unusual feature is a pair of switch-selectable input channels. This option lets you choose between VHF and HF wavelengths by flipping a single switch. The Interface II can be tuned with a built-in set of LEDs, or you can plug in an oscilloscope unit.
ADVANCED HAMS ONLY
The Kantronics UTU ($199.95) seemed to be as reliable as the Interface II. But it requires an RS-232 serial port--which means you can only use this model with an Atari if you have the 850 Interface Module (See Antic, August 1985, page 16.)
The UTU (Universal Terminal Unit) has a built-in ROM that must be accessed with a BASIC program which you'll have to write yourself. The manual offers only a sample program written in IBM BASIC. This is not an interface you can just plug in, it will require some experimentation.
However, the UTU might be the best choice for hams interested in writing their own software, particularly since the built-in ROM allows you to access this device in BASIC. Thus the need for packaged softwareis eliminated.
Antic also sent me the RM 1000 by Macrotronics, which is a fantastic piece of hardware. Unfortunately, when I tried to phone some questions to the Turlock, CA manufacturer, I discovered they were now out of business.
Still, if you ever find an RM 1000 for sale someplace you ought to consider it. It features two LED bar-graphs for tuning both Morse code and radio transmissions, and it excels at rejecting background noise. List price used to be $239, with 32K disk software for $59 or cartridge for $99.
I should mention that my own personal radio modem is the MFJ RTTY/CW Computer Interface, Model MFJ-1224. ($99.95). I have been using this LED-tuned unit for some time and am completely satisfied. I was also pleased to find that it works fine with all the Kantronics software I was testing.
Documentation for my MFJ was a scant few pages, but it was adequate to get me hooked up and running without too much trouble. MFJ Enterprises can be reached at P.O. Box 494, Missisippi State, MS 39762. (601) 323-5869.
Just as you need special software to use your Atari with a telecommunications modem, you also need software for your ham radio modem.
Kantronics has three software cartridges that work with any 8-bit Atari. Each package includes a completed cable for connecting the computer and the modem, so you won't need to do any soldering.
Hamsoft ($49.95) is the no-frills package. However, current revision AH 2.2 is much improved over the ancient version I have been using in my shack. This software doesn't work with a disk drive. But you can load from cassette as many as 10 frequently used messages (such as your call sign), and then "autodial" them with a single keystroke.
The program is menu-oriented and very easy to use. Morse code can be copied at up to 99 words per minute, and all standard RTTY speeds are supported.
Hamsoft/AMTOR ($79.95) adds to the basic package the capability to use AMTOR. This is a recent ham mode that contains an error checking protocol resembling XMODEM, but it is only allowed on the high frequency (HF) bands. If you will regularly be using your rig on HF bands, then you probably would like this feature.
AMTOR can't be used by a VHF nut like me. I work exclusively in the "two-meter band" which covers the frequencies from l44 to 148 megahertz (MHz). This is a band of frequencies somewhat above the standard FM broadcast stations, which use 88 to 108 MHz. One MHz is one million cycles-per-second.
Hamtext ($99.95) is the no-holds-barred version of Kantronics software. I'm so spoiled by testing it for this review that it's hard for me to return it to Antic for shipment back to the manufacturer.
The main advantage of Hamtext is that it can handle a disk drive. And it also includes more options than Hamsoft.
Hams can establish their own size limitations on the transmission buffer. Message ports (buffers) use only the amount of memory that the messages actually occupy. This frees the remainder of memory for use as a holding buffer. The buffer can be edited, saved to printer or disk, or viewed onscreen. The operator is thereby free from needing to monitor constantly. I have no hesitation in recommending Hamtext software to anyone who can live without AMTOR.
Bill Marquardt commutes from Fairfield, California to San Francisco for his job with the U.S. Postal Service. He is a member of ABACUS, The San Francisco Atari users group.