Eico HFT-92
Eico took its HFT-90 FM tuner, bolted a ferrite-rod AM section onto the same chassis, and called it the HFT-92.
Overview
The HFT-92 is the Eico HFT-90 high-fidelity FM tuner with AM tuning added to the same chassis. Eico's own documentation describes it that way and treats the FM side as unchanged. Only the AM specifications are broken out separately. The FM specs are simply listed as "same as HF90A." A listener who wanted both broadcast bands in one box didn't have to buy two tuners or accept a compromised front end.
On the AM side, Eico rated sensitivity at 20 microvolts for 0.8 volts of output at a 15 dB signal-to-noise ratio. IF bandwidth was 8 kc at 6 dB, and image rejection was 40 dB. Total harmonic distortion was specified below 2% up to 70% modulation. The antenna is the detail that dates it: a built-in ferrite rod, plus terminals for an external antenna if the rod wasn't enough. Frequency response on AM was quoted at 20-500 cps ±3 dB. That's narrow, but it's the AM broadcast band's limitation, not the tuner's. Hum sat 60 dB below 1 volt, and minimum output was 0.8 volt into a 20-microvolt input at 30% modulation. Controls were kept to four: tuning, volume, power on-off, and an FM-AM selector.
The FM half is an HFT-90, and the HFT-90 is the reason Eico's tuner line has a following. The unit carries an output intended for Eico's MX-99 FM-Multiplex Adaptor, which is how owners got stereo out of it. Eico designed the MX-99 to work with the HFT-90, HFT-92, and ST-96 tuners. Eico's literature describes the adaptor's ten-stage "zero phase shift" circuit as delivering 35 dB of channel separation. It suppresses the SCA background music carrier at 67 kc, the reinserted 38 kc subcarrier, and the 19 kc pilot carrier and its harmonics. Eico flagged these as a problem for tape recording, where they could beat against a recorder's bias oscillator and produce audible tones. The MX-99 was self-powered, switched automatically between stereo and mono, and used low-impedance cathode follower outputs so long cable runs wouldn't degrade the signal.
In 1964 the tuner was mono, and the stereo came from a separate box. HiFI-Stereo (1964, p.53) listed the factory-wired HFT-92 at $119.95, with a metal cover at $7.50 and a walnut case at $19.95. Eico's own kit pricing for the tuner ran $59.95 in kit form and $94.95 wired, and the company offered a W-70 walnut cabinet for the HFT-92 and HFT-94 at $12.50. The MX-99 adaptor was priced at $39.95 as a kit and $64.95 wired in Eico's early-1960s catalogs. A later listing showed $36.95 kit and $59.95 wired. A buyer was looking at a two-box stereo front end for roughly the price of a single mid-range receiver.
The HFT-92 is a metal-case bookshelf unit, and Eico's documentation notes the kit included the metal cover and an FET. The MX-99 used two 12AU7s, one 12AT7, one 6AU6, one 6D10, one 6X4, and six diodes. It drew 37 watts at 117 volts and weighed 7 lbs in a chassis measuring 3½ by 6½ by 9½ inches. None of that is exotic. The schematic exists, the tubes are common, and the circuit is straightforward enough that a patient hobbyist can keep one running.
The HFT-92 sits in Eico's Standard Series alongside the tuners and amplifiers that made the company's reputation in the late 1950s and early 1960s, before the pivot to solid-state Cortina gear and eventual retreat from audio. Collectors usually chase the FM-only HFT-90 harder. The HFT-92 is the more useful one if AM matters to you, and it's priced accordingly. The MX-99 adaptor shows up on the used market often enough to be findable.
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Related Models
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- Eico 3570 (1972)
- Eico HF-65A (1958)
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- Eico MX-99 (1961–1962, possibly 1963)
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- Braun AUDIO-250 (1965)
- Magnavox Component Systems (1972)
- Acoustic Research AR (1967-1976)
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