Note
The HD-1530 connects between a receiver audio output and a speaker. It keeps the speaker muted until it hears the correct Touch-Tone code—your basic tone-calling scheme. It also provides a contact closure for control of a repeater or autopatch (or anything else for that matter) upon receipt of the right code.
The only front panel control is the on/off push button. Three front panel LEDs indicate power on/off, tone valid, and device on/off. A user programmable three- or four-digit Touch-Tone sequence operates an external device for a spoof length of time, or toggles the device on and off.
Rear panel terminals include receiver audio in, audio out, relay in, relay out, mute and three grounds. RELAY IN and RELAY OUT represent a pair of relay contacts that may be wired as normally open or normally closed. The contacts are rated for 24 VDC, 1 amp, resistive. MUTE is a logic output. When a valid code is detected, MUTE is low. In the absence of a valid code, MUTE is high.
The decoder must be programmed or for several options. These involve various combinations of wires, jumpers and DIP switches, and the adjustment of some controls. Wire connections use push-on terminals and are easy to reconfigure.
The decoder is designed specifically to accept audio from a speaker output and has a protective 11Ω load, in the form of two 22Ω, 1-watt resistors (R116 and R117), located near the relay. If you want to feed tones to the decoder from a high impedance device, the 11Ω load may safely be removed.
Full decoding of all 16 DTMF codes: 1 through 9, 0, *, #, A, B, C, D
Input combination code: programmable, any series of three or four tones
Three-digit combinations: jumpered for an input combination of 3
Sequential memory: after first digit, each 3 or 4 digit code must appear in sequence or decoder will reset
Wrong number reset: after first digit entered, circuit detects incorrect input codes and decoder will reset
Timed entry: adjustable from 3 to 25 seconds, starts on second digit entry
Time out: adjustable from 25 seconds to 8 minutes, remotely resettable
Sensitivity: < 30 mV @ 11Ω with sensitivity control at maximum
Response time to input signal: < 160 mS
Relay terminal rating: 24 VDC @ 1 amp, resistive
Impedance: 11Ω when in monitoring mode
Operating temperature range: 0 F to 140 F
Power requirements: 7.5 to 11 VAC, or 11 to 16 VDC; 175 mA maximum, polarity not critical
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
