Crown FM TWO FM-2 Vintage Tuner, Rackmount Silver Face

Crown FM TWO FM-2 Vintage Tuner, Rackmount Silver Face. WORKING. The Crown FM Two is an FM tuner of advanced design whose compact dimensions and appearance complement those of the company’s Straight Line Two preamplifier and Power Line Two power amplifier. Because of their unified design, the three components can be “stacked” in a single optional walnut cabinet to form a “receiver” of outstanding quality. The FM Two is only 1-3/4 inches high, with a satin-finish silver-color front panel fitted with handles. The panel is 19 inches wide and the tuner is 13-3/4 inches deep; it weighs approximately 9-1/2 pounds. Price: $599. The Crown FM Two is a digital-synthesis tuner whose reception frequency is shown on a large fluorescent digital display in the center of the panel. The bright 1/2-inch-high numerals are readable from a considerable distance and can be dimmed by a front-pan-el switch if desired. To the right of the display are two flat momentary-contact scan/ tune buttons and a scan lock button. With the latter out, holding either scan/ tune button down causes the tuner to scan in the selected direction (up or down in frequency) in steps of 200 kHz, corresponding to North American channel assignments for FM. Export versions are set up at the factory for the channel spacings (such as 50 kHz) used in other parts of the world. A momentary touch on a scan/tune button will cause the frequency to step by one channel width. If the scan lock is engaged, a single touch on a scan/tune button will cause the tuner to scan until it acquires a signal above the muting threshold, where the tuning stops and the FM Two unmutes. At the right side of the panel are a memory button and six preset buttons. A station frequency can be stored in any of the memory locations by pressing memory (which lights an amber indicator above that button) and then, within five seconds, pressing the desired preset button. The station can be recalled instantly at any later time by touching that button. A constantly energized separate power supply in the tuner keeps the memories “alive” when it is not in use, and a very large internal capacitor (0.47 farad) retains sufficient charge to support the memories for at least five days with no power available to the tuner. To the left of the frequency-readout window (which also reveals a five-segment signal-strength readout and a stereo indicator) there are six round pushbutton switches. In addition to the power switch (with an adjacent red light), these include an FM de-emphasis switch (75- or 25-microsecond characteristics), a stereo-noise filter that blends high frequencies to reduce hiss on weak signals, a mute switch, a stereo/mono switch, and the fluorescent-display dim switch. With all the buttons in their “out” positions, the tuner is set up for normal operation. The rear of the Crown FM Two contains the audio-output jacks, each with its own level control, and a coaxial connector for the 75-ohm antenna input. For installations using a 300-ohm antenna system, a 300- to 75-ohm balun matching transformer is supplied with the tuner. There is also a small remote connector whose function is not mentioned in the otherwise complete instruction manual. The circuitry of the Crown FM Two is unusual in several respects. The “front end” has three cascode J-FET r.f. amplifiers whose seven tuned circuits give the tuner exceptional immunity to overloading by strong signals plus excellent image rejection. The first i.f. is at 10.7 MHz, with lin-ear-phase (constant group-delay) ceramic filters that make possible the tuner’s very low distortion rating of less than 0.05 per cent for both stereo and mono. There is a second conversion to 1.96 MHz, the operating frequency of the pulse-counting digital detector, which not only eliminates any alignment or drift problems in that part of the tuner but has an inherently wide bandwidth that accommodates excessive transmitter deviation without a significant increase in distortion. Although crystal-con-trolled frequency synthesizers are no longer a novelty in consumer-oriented tuners, the circuit in the FM Two operates rapidly and smoothly, and with no idiosyncrasies. Laboratory Measurements The 75-ohm antenna input of the Crown FM Two was driven through a resistive network that matched it to the 50-ohm output impedance of our Sound Technology 1000A signal generator. The “dBf ” notation of the tuner test standard makes sensitivity ratings independent of the impedance level. If one were to rate the tuner sensitivity in terms of microvolts, the numbers would be half as much as for a 300-ohm antenna input, and this might give a misleading impression of the tuner’s actual sensitivity. In mono, the usable sensitivity was 11.6 dBf and the 50-dB quieting sensitivity was an almost identical 12 dBf. The stereo-switching threshold was 25 dBf, and the distortion was already under 1 per cent at that input level. In other words, clean and undistorted reception can be expected from an