Eico Model 3200 Cortina (1967)
A budget FM stereo tuner that arrived with its hard parts already built, and measured better than its own maker claimed.
Overview
The Model 3200 was Eico's entry in the "Cortina" series, a line of all-solid-state stereo components. The company pitched the line on one idea: near-perfect stereo could be had at moderate manufacturing cost, and anything above that price was "marginal and probably inaudible." Eico's advertising called the Cortina components "100% professional" and compact, with a "low silhouette" the company found aesthetically striking. The 3200 was the tuner of the family, a solid-state FM/MPX automatic stereo unit. The 1967 launch advertising priced it at $89.95 as a kit or $119.95 factory wired. Prices drifted over the run. By 1968 a period writeup listed the kit at $99.95 and the wired version at $139.95, and one 1967 ad placed the wired figure at $129.95. The exact price depends on the catalog and year.
Very little of the 3200 was left for the builder. The RF, IF, and multiplex circuitry came completely assembled and pre-aligned on printed circuit boards. The builder wired only the non-critical power supply and the interconnections between the boards. A period review put a novice on the job and reported roughly ten hours of careful work, with the caveat that a normal builder should finish in about half that. The alignment-sensitive front end, where most tuner kits go wrong, was done at the factory.
The front panel is sparse, with four controls: a tuning knob, a Mono-Auto/Stereo switch, an AFC rocker, and power. There's a D'Arsonval signal-strength tuning meter and a stereo indicator lamp. The tuner is self-switching. Leave it in Auto-Stereo and a stereo station feeds left and right outputs, while a mono station's signal goes to both jacks automatically. Flip to Mono and even a stereo broadcast is summed to both outputs. The stereo lamp lights whenever a stereo signal is present, regardless of mode.
On paper the numbers were respectable for the money: 2.4 microvolts for 30 dB quieting IHF sensitivity, 40 dB channel separation at 1,000 Hz, a 60 dB signal-to-noise ratio, 4.5 capture ratio, and audio frequency response of 2 to 15 kHz ±1 dB. The independent measurements came out better in places. A period review measured frequency response within ±2 dB from 30 to 12,000 cps in both mono and stereo. It found mono noise better than 70 dB down with a standard 1,000-microvolt input, a full 10 dB better than Eico's own claim. Stereo noise came in at 60 dB down on both channels. Channel separation measured 28 dB at 1 kHz and 12 dB at 12 kHz. Instrument-aligning the multiplex circuit pushed that to 35 dB at 1 kHz and better than 14 dB at 12 kHz. Instructions were included, but you need test gear.
There were flaws. The same review noted that from 106 to 108 mc the AFC tended to pull tuning off center. Distortion was actually lower when tuning for a peak meter indication than when relying on AFC pull-in. The tuner drifted so little that the AFC was nearly unnecessary anyway, and the reviewer's advice was to leave it off and tune by the meter. A later Audio (June 1969, p.40) profile compared a factory-wired unit against one built by a relatively inexperienced do-it-yourselfer and called the 3200's circuit "quite basic": only bi-polar transistors, no FETs, with three in the RF section and four in the IF. Audio (August 1968, p.84) also used the 3200's oscillator section as a teaching example in its "ABZs of FM" column, walking readers through how AFC works using the tuner's own schematic.
For collectors, the 3200 is a sensible way into the Cortina line and into Eico kit tuners generally. The pre-aligned boards mean a used example is less likely to have been mangled by a previous owner's soldering iron than a full-kit tuner would be. The simple bi-polar circuit is straightforward to service. The usual cautions apply to any 1960s solid-state tuner: check the power supply, clean the controls, and don't assume the multiplex alignment is still where it left the factory. The AFC-off-center quirk is a design characteristic, not a fault, so don't chase it as a repair. The wired version ran roughly a third higher than the kit when new. A clean factory-wired unit is the more desirable find, but a well-built kit is no lesser performer.
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