Eico 667
The Eico 667 is a dynamic mutual conductance tube tester, sold during the 1950s and 1960s as an inexpensive alternative to the commercial Hickok 539 series, which cost over $200 at the time. Eico marketed it to hobbyists and technicians. It came as a kit and, per at least one source, in wired form as well.
It's a compact, self-contained unit that tests tubes for shorts, leakage, and quality. A built-in roll chart covers 3,400 tube types, and that chart is a big reason the unit is still useful today. The tester gives actual transconductance readings with separately adjustable screen voltage. It also has low-voltage tube tests for both filament and plate currents, a leakage test applied across all tube elements, a shorts test using a neon lamp, and a direct-reading grid emission test. A 1959 issue of HiFI-Stereo (February 1959, p.41) compared the Eico HF-851 stereo preamplifier against other models and listed its price at $64.95. Filament voltage is continuously variable from 0.5 to 75 volts. Screen and plate voltage are each adjustable from 25 to 300 volts. The meter is a 4½-inch, 200-microamp movement, and the unit runs on 105-125 volts AC, 50-60 cycles, drawing 30 watts. One source describes a 100-microamp meter movement instead. Sockets include 9-pin miniature, octal, loctal, and a 7-pin socket covering sub-miniature types. It also has facilities for testing "magic eye" tuning indicators. The circuit uses a 6AV6 as rectifier/regulator and a 6V6 as voltage regulator, with a built-in voltage regulator and a continuously variable filament supply.
The record on price is muddled. One source lists a kit price of $59.95, while another gives an original retail price of $69.95. The 667 is described as a precision instrument, quite accurate and easy to use for its price point, and it remains a favorite among collectors. No production years, dimensions, or weight are documented, and no current market prices are recorded in the archive's sources.
- Tests shorts, leakage, and quality; mutual conductance readings
- Built-in roll chart covering 3,400 tube types
- Filament: 0.5–75V continuous; screen/plate: 25–300V adjustable
- Meter: 4½", 200 µA movement
- Operates on 105–125V AC, 50–60 cycles; 30W
- Sockets: 9-pin miniature, octal, loctal, 7-pin sub-miniature
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