Note
The HD-4040 was Heath’s first packet product. It has most of the features one would expect in a TNC, including a mailbox, a beacon mode, and a repeater mode.
Front panel indicators include:
PTT: lights when the transmitter is being keyed.
SPARE: lights when the power switch is on.
CWID: lights when CW identification is being send, otherwise is randomly on or off.
TXD: lights when packets are being transmitted, otherwise is randomly on or off.
DCD: light when packets are being received.
RESET: lights during normal operation.
REC AUDIO: these should barely flicker when your radio’s volume control is set properly.
Features include the use of a 6809 CPU, 32K of ROM (as 4 x 2764) and 8K of RAM (as 1 x 6264) expandable from 2K to 16K RAM or ROM and RS-232C interface baud rates from 50 to 4800 (optional to 19,200).
A parallel port provides controller channel and command channel, diagnostic signal port, and a PROM programmer port. The modem input is filtered prior to demodulation and the filter constant can be changed by a plug-in header. Modulator is 1200 baud. An external modem can plug in to completely bypass the internal modem for faster baud rates.
Operating commands can be stored in non-volatile RAM —128 4-bit locations. The HD-4040 came with both an assembly manual and a user manual. Having both would be essential. Requires and AC voltmeter or oscilloscope for calibration.
References:
Review. QST. Nov 1985, p. 54.
Using with a RTTY terminal unit. Aug 1986, p. 59.
Upgrade. 73 Amateur Radio. Nov 1990, p. 19.
Clock: 7.3728 MHz crystal oscillator for UART, switched-capacitor filter and E&Q systems
Serial port: RS-232C interface to terminal or computer; 50 to 4800 baud (19,200 optional)
Parallel port: controller status and command channel, diagnostic signal port, and PROM programmer port
Protocols: AX.25 and VADCG.
Operating modes: command, conversation, and transparent.
Operating temperature: 32 F to 104 F
Power requirements: 120 VAC, 60 Hz, 15 watts
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
