Note
Introduced in the fall of 1955. Unlike the AR-1 and AR-2, the AR-3 uses only five tubes, though advertising was sometimes unclear or inaccurate on this point. The 12BA6 BFO was removed and the circuit redesigned so that the 12AV6 (2nd detector, AVC, and first audio amp) could also act as the BFO.
The front panel layout changed a bit, now including an antenna trimmer control and a band switch with a larger knob located in the middle of the unit. Also, the frequency coverage differed slightly—550 kHz to 30 MHz in four bands, with a 455 kHz IF. Civil defense frequencies and Amateur radio bands are marked on the dial.
The selectivity was improved with the use of new slug-tuned high Q coils and better IF transformers. These changes did nothing to improve the unit’s stability, which was still poor.
The AR-3 also includes an octal accessory socket to supply power for a Q multiplier, which could considerably improve the AR-3’s selectivity, although Heath’s QF-1 Q multiplier didn’t arrive until 1959. An IF input jack on the rear panel permits connection to the QF-1.
The AR-3 uses a transformer power supply and features an electrical band-spread, separate RF and AF gain controls, an AGC and BFO, noise limiter, headphone jack, and an internal 5.5 inch speaker. Unlike the AR-1 and AR-2, the AR-3 features a lighted dial. The gray fabric-covered plywood cabinet was still an extra $4.50.
Caution: The receiver is not fuse protected, and the power supply does not include bleeder resistors.
References:
Review. Popular Electronics, Feb 1956, p. 64.
Doublet antenna. Popular Electronics, Jan 1959, p. 66.
Stabilizing. CQ, Jan 1960, p. 47.
Improvements. CQ. Jun 1961, p. 41.
Improvements (correction). CQ. Jul 1961, p. 20.
Bandspread improvement. CQ. May 1962, p. 76.
Overview. Electric Radio. Oct 2018
Frequency range: 550 kHz to 30 MHz in four bands
Power requirements: 120 VAC, 50/60 Hz, 40 watts
Tubes: (1) 5Y3, (1) 12V6, (1) 12BE6, (1) 12BA6, (1) 12AV6
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
