Classic Computer Magazine Archive COMPUTE! ISSUE 47 / APRIL 1984 / PAGE 100

Radiotap For VIC And 64

Dan Carmichael, Assistant Editor

The Radiotap by Kantronics is an impressive package that allows you to interface your Commodore 64 or VIC to a shortwave or ham radio receiver. It will automatically interpret communications such as Morse code and radioteletype (RTTY) and display them on your monitor. RTTY is used by various services, from foreign embassies to news wire services. The Radiotap can interpret both standard RTTY and the newer ASCII RTTY.

Several Modes Are Available

In the Morse code mode, the Radiotap reads the incoming signals, and automatically adjusts the receiving speed of the computer. It has the ability to adjust to speeds ranging from 0 to 99 words per minute. All you have to do is turn on the Radiotap, tune in your radio, sit back, and "read the mail."

In the RTTY and ASCII modes, you also have the ability to decipher coded or scrambled messages. These options include bit switching, inverting bit patterns, and the ability to vary the baud rate (receiving speed) to nonstandard settings. In these modes, however, receiving speeds must be set manually.

The Radiotap also has a scope feature. It is very useful when analyzing RTTY signals coming in at nonstandard baud rates or which are encoded. You can display the incoming signals on your screen in graphics form, which allows you to measure the timing of the incoming signals (bits) and helps you determine which ciphering techniques, if any, are being used.

Another nice feature is the printer option. By pressing a single key, you can produce a printout in addition to the monitor display. This feature, however, has hardware limitations. It is designed for the Commodore 1525 printer, and may not work with other printer/interface combinations. It did not work with the Epson printer interfaced to a 64 with a Micro-Electronix serial interface. However, it is reported to work with the Cardco interface. For more information, con-tact Kantronics at the address below.

The Radiotap also has a 24-hour clock, set by the user, that is always displayed at the top of the screen.

Small Inconveniences

There were a few small inconveniences encountered while setting up the Radiotap. First, you must construct the patch cord to connect the Radiotap interface to the shortwave receiver. This requires a little light soldering to attach two plugs to the cord. Second, the dual voltage power supply included with the Radiotap is switch-selectable to either six or nine volts. However, no mention was made of this in the instruction manual. After experimenting for some time with both voltages, we selected nine volts, the correct setting.

The Radiotap comes with the radio-to-computer interface, software in cartridge form, and all the necessary wiring and plugs to connect it up (except the cord to the radio).

Also included is a complimentary copy of the book Confidential Frequency List published by Gilfer Associates in Parkridge, New Jersey. But because this book deals largely with items that are not related to either Morse code or RTTY, a better choice might have been RTTY Frequencies, also published by Gilfer Associates.

All in all, the Radiotap is a fine product, and you can spend many enjoyable hours reading foreign embassy and wire service messages. The Radiotap is for receiving only; there are no transmit options.

1202 East 23rd St.
Lawrence, KS 66044
(913) 842-7745 $199.95