Note
The GR-81 is a simple 3-tube regenerative unit covering from 140 kHz to 18 MHz in 4 bands. It had a place in the catalog for 11 years and was an inexpensive, easy project designed for beginners. The receiver's selectivity, sensitivity, and stability are awful, but as long as you keep your expectations down you won’t be disappointed with its performance. To make sure customers knew it was not some cheap AD/DC set (so common of the era) Heath advertised the GR-81 as having a “shock free” transformer power supply. The GR-81 includes a built-in speaker and comes equipped with a headphone jack and provisions for both long and short antennas.
Heath notes that on bands A and B, the LONG antenna input will provide better results. The company goes on to say that on bands C and D, a relatively short antenna (less than 50 feet) will work better. It should also be noted that using the SHORT antenna input will disturb the dial calibration and frequency range, and that it may be necessary to set the main tuning dial to a slightly higher frequency to receive the same station. A good ground is essential for satisfactory operation of the receiver. Refer to Figure 1 for antenna connections.
The pilot light comes on only after the rig has warmed up—be patient. The cabinet is beige and the front panel is green with white dial markings.
Detailed specifications not provided.
References:
Brief description. Popular Electronics, Mar 1962, p. 94.
Review. Electric Radio. Jun 1997
Frequency coverage: 140 kHz to 18 MHz in four bands
Audio output: 1 watt
Power requirements: 120 VAC, 50/60 Hz, 30 watts
Tubes: (1) 12AT7, (1) 50C5, (1) 35W4
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
