51S1

Collins 51S1 General Coverage Receiver
Description and Specs

Collins 51S1 Receiver Summary

General Coverage Receiver
Manufactured by Collins Radio
Introduced in 1959
New Price from 1959 thru 1963: $1828
Tubes/Stages: 17/ 1-RF, 3-IF
Audio Output: 6BF5/1.0W
Product Detector: Yes
Filter: Mech
Size: 7.75"x14.75"x14.0"
Approx. Weight: 28 lbs

Tube List: 5670 (1), 6AK6 (1), 6AU6 / 7543 (2), 6BA6 (4), 6BF5 (1), 6DC6 (1), 6EA8 (5), 12AX7 (2).
Semiconductor List: 1N1492 (3), 2N388 (1), 2N6373 (4), 1N34A (4).

Collins 51S-1 Receiver Specifications

The 51S-1 receives USB, LSB, AM, and CW signals in the range of 0.2 to 30.0 MHz. Coverage is continuous in thirty 1-megahertz bands. It is mounted in a perforated wrap-around cabinet similar to and compatible with the 75S3 and 32S3. It is equipped with an AC power supply capable of 115- or 230-volt, single- phase, 50- to 400-Hz operation. The 51S-1A is similar, except that it is fitted with a 28-volt DC transistorized power supply. The rack-mounted AC version is designated as model 51S-1F. The rack-mounted DC version is designated as model 51S-1AF. The 51S-1B is similar to the 51S-1, but it has a rear-mounted junction box that provides military-type connectors for power, control, audio, and antenna lines.

Frequency range:    0.2 to 30.0 megahertz in thirty 1-megahertz bands continuous coverage.

Modes:   Upper sideband, lower sideband, AM or CW.

Power consumption:    125 watts.

Type of service:    Fixed station attended with provision for remote control of rf gain.

Rf input impedance:    50 ohms, unbalanced.

500-kHz if. output at J9:    50 mv minimum into 50-ohm load with 5-uv input signal.

Matching speaker impedance:    4 or 600 ohms.

Balanced line out impedance:   600 ohms balanced, center-tap ground reference or floating. (For 51S-1B, 150 ohms floating.)

Matching phone patch impedance (local):   500 to 600 ohms.

Frequency stability:   During temperature change from 0 to +50 øC, after 20 minutes warmup, audio
    output frequency will not vary more than +/-885 Hz for carrier frequencies from 2 to 7 MHz. From
    7 MHz to 30 MHz, stability varies from 36 PPM +/-400 Hz at 7.00 MHz (652 Hz) to 27 PPM +/-400
    Hz at 30 MHz (1210 Hz). For +/-10% line voltage variation, frequency varies not more than + 100 Hz.

Calibration accuracy:.   When zeroed to nearest 100 kHz calibration point, the frequency will be within +400 Hz.

Dial backlash:.   Not more than 150 Hz.

Audio-frequency response:

    AM.   100 to 2500 Hz +/-6 db (line channel). 200 to 2500 Hz +/-6 db (local channel).
    SSB (high-frequency limit determined by filter bandwidth) 350 to 3050 Hz +/-3.5 db (line channel),
    350 to 3050 Hz +/-3.5 db (local channel).

Audio output distortion (SSB test signal 100-microvolt input, 1.0-watt local output, 1-mv (0 dbm) line output)
     Local:   Not more than 10 percent.
     Line:   Not more than 1.2 percent.

Q-multiplier rejection notch depth:   Not less than 40 db.

Receiver sensitivity (nominal)
     AM....3.0 microvolts for not less than 10-db signal + noise/noise (2 to 30 MHz).
               15.0 microvolts for not less than 10-db signal + noise/noise (0.5 to 2 MHz).
                20.0 microvolts for not less than 10-db signal + noise/noise (0.2 to 0.5 MHz).
                With 55G-1 Preselector, 5.0 microvolts for not less than 10-db signal + noise/noise (0.2 to 2.0 MHz).

    SSB and CW:   0.6 microvolt for not less than 10-db carrier on carrier off (2 to 30 MHz).
                 3.0 microvolts for not less than 10-db carrier on carrier off (0.5 to 2.0 MHz).
                 4.0 microvolts for not less than 10-db carrier on carrier off (0.2 to 0,5 MHz),
                 With 55G-1 Preselector, 1,0 microvolt for not less than 10-db carrier on carrier off (0.2 to 2,0 MHz).

Selectivity:
                CW (at 6 db points):.   800 hertz bandwidth, nominal. (650 Hz minimum, 950 Hz maximum,
                        300-Hz maximum bandwidth optional),
                SSB (at 3.5db points):   2.75 kilohertz bandwidth (2.4 kHz bandwidth optional),
                AM (at 6 db points):   5.0 kilohertz bandwidth minimum, (at 60 db points), 22,0 kilohertz bandwidth maximum.

Spurious responses (above 2 MHz)
        Internal spurious signals:   Less than one microvolt equivalent signal.
        Other spurious signals:.   Not less than 70 db down, except from 4.8 to 5.2 MHz, not less than 40 db down.
        Image response:.   Not less than 50 db down from 2 to 25 MHz; not less than 40 db down from 25 to 30 MHz;
        referenced to midband.

Size:   Cabinet version: 7-3/4 in. high by 14-3/4 in. wide by 14 in. deep
          Rack-mounted version: 8-3/4 in. high by 19 in. wide by 15 in. deep.

Weight:   28 pounds

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