Note
Released in time for Christmas in 1972. This very successful radio was Heath’s first venture into scanners. It is a crystal-controlled 8 channel unit, using 30 transistors, 8 ICs, and 17 diodes.
The GR-110 covers any 9 MHz band segment between 146 and 174 MHz and scans at 17 channels per second. Sensitivity is rated at better than 0.5 µV (1.0 µV for 20 db of quieting). The 10.7 MHz IF employs crystal filters.
Features include a priority channel (channel 0), a 4-second scan resume delay (not adjustable or defeatable), a manual override channel step switch, and 8 pushbuttons to select or de-select each channel.
A unique feature is the single digit channel readout—an incandescent, seven-segment device, type 8015A. Downside: If a segment of this readout burns out, the entire device must be replaced, and the part may be very hard to find. It is important to note that the radio will continue to function normally even with burned out readout segments. The technically inclined user could replace this device with a seven-segment LED.
One of two modes of operation could be chosen during assembly. In one mode, the channel readout runs continuously. In the other mode, the channel indicator lights only when the squelch opens. The choice involves a green wire that comes from the underside of the chassis. Refer to photo for configuration options.
The GR-110 comes with a built-in speaker, mounting bracket, external speaker jack, and two power cables—one for 120 VAC, 50/60 Hz operation, and one for 12 VDC operation. The unit has an RCA jack for a 50Ω antenna—there is no built-in telescoping antenna.
Some units may make a faint ticking sound while scanning, and some units may make a distinct “pop” each time the priority channel is sampled. The popping sound is a little irritating but can be eliminated by turning off the priority channel.
The GR-110 has a black and gray front panel with chrome trim and a wrinkle black case, though some may have been supplied with light green cases. Heath sold a ton of these scanners. They were popular for monitoring local repeaters and law enforcement, etc. In the end, the GR-110 proved too expensive and was replaced with a more conventional-looking scanner—the GR-1130 series.
The scanner can be aligned with or without instruments, but do not attempt to align the GR-110 without the book.
CRYSTAL FREQUENCY CALCULATION
Crystal frequency = (operating frequency in MHz - 10.7) / 3.
References:
Review. QST. Aug 1973, p. 58.
Review. 73 Amateur Radio. Nov 1973, p. 39.
Review. Popular Electronics, Dec 1973, p. 68.
Frequency range: 146 to 174 MHz
Scanning range: any 9 MHz segment within frequency range
Sensitivity: less than 0.1 µV for 20 db quieting
Usable sensitivity: less than 0.5 µV
Adjacent channel rejection: –40 db (±30 kHz spacing)
IF: 10.7 MHz
IF rejection: greater than –80 db
Image rejection: greater than –40 db
Modulation acceptance: ±7.5 kHz
Input impedance: 50Ω
Scan rate: approximately 17 channel per second
Audio output: 2 watts into a 4Ω load, with less than 10% distortion
Power requirements:
120 VAC, 50/60 Hz, 13 watts OR
13.8 VDC, 275 mA squelched, 800 mA full audio
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
