Note
The MR-1 and MT-1 are matching rigs designed primarily for mobile operation, although fixed-station use is possible. A QST review marveled at that fact the space occupied by both units was “a mere cubic foot.”
The MR-1 receiver is an 8 tube, single-conversion superheterodyne design covering 80-10 meters and will receive AM, CW, and SSB signals. No PC boards are used—all wiring is point to point. It uses a crystal lattice filter and has a 3000 kHz IF. Sensitivity was advertised as better than 1 µV on all bands. Selectivity is 3 kHz at 6 dB down, 10 kHz at 60 dB down. Two different detectors are used—a conventional diode type for AM and a product detector for CW and SSB.
The receiver can be used as a mobile or fixed-station radio with the appropriate power supply and is designed for use with either the MP-1 or the HP-10 (for mobile use) or the HP-20 (for 120 VAC use).
Features include a noise limiter, AVC, voltage regulation, and an illuminated S-meter, but no built-in speaker. Additional features include a built-in series ANL, front panel selection of fast and slow AVC action, and outputs for an 8Ω speaker and 500Ω headphones.
The MR-1 uses the same gear and pulley tuning mechanism and the same rotating dial drum as are used in the MT-1 (see comments under MT-1) and is as difficult to fix. Check the dial drum for cracks before you buy.
Front panel controls include mode selector, RF gain, AF gain/power on/off, noise limiter on/off, AVC on/off selector, main tuning, band switch, BFO tune, and antenna trimmer.
Rear panel connections include an SO-239 for a 50Ω antenna, an RCA jack for an 8Ω speaker (there are no provisions for headphones), and a 6 pin power connector. If desired, power for the MR-1 can be taken from a loop-through mating connector on the MT-1.
In 1962 the MR-1 was redesigned to better accommodate SSB operation. The new rig was designated the HR-20 (no Indian name used), but is almost identical in outward appearance. Take care not to confuse them. Refer to the MT-1 for additional discussion and information.
The MR-1’s paint color is Heath’s standard two-tone green. The AK-6 mobile mounting bracket is almost always missing.
References:
Review. CQ. Oct 1959, p. 52.
Review. QST. Apr 1960, p. 41.
Power supply for. CQ. Jan 1961, p. 67.
Tips. CQ. Oct 1961, p. 83.
Upgrading. CQ. Jun 1964, p. 55.
Intermittent BFO (brief). CQ. Mar 1965, p. 67.
Drift problems. CQ. Apr 1967, p. 86.
Frequency coverage (MHz): 3.5 to 4.0, 7.0 to 7.3, 14.0 to 14.35, 21.0 to 21.5 , 28.0 to 29.7
IF frequency: 3000 kHz
IF crystal filter:
center frequency: 3000 kHz
bandwidth at 6 db down: 3 kHz
bandwidth at 60 db down: 10 kHz maximum
Sensitivity: better than 1.0 µV on all bands
Signal to noise ratio: more than 10 db at 1.0 µV input
Power requirements:
6 volts at 3.3 amps or 12 volts at 1.65 amps AC or DC
250 VDC at 125 mA
Tubes: (1) 0A2, (1) 6AQ5, (1) 6BE6, (2) 6BZ6, (2) 6EA8, (1) 6T8
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
