FM "Relay" Receiver

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Inovonics' Model 630 is a frequency-agile, digitally tuned receiver for FM translator and other critical off-air reception applications. A switchable IF bandwidth helps solve difficult adjacent-signal problems, and readouts of signal strength and multipath distortion aid antenna alignment. Selectable options and alarms may be remotely controlled or monitored. The front-panel bargraph display gives accurate indication of MPX and stereo audio levels.


  • A professional FM receiver for translator service

  • Composite/MPX and demodulated stereo outputs

  • Dual IF bandwidth; built-in squelch and alarms



Tuning Range

DIP-switch programmable; 87.9MHz to 108.1MHz in 100kHz increments.

Antenna Input

75-ohm “F” connector.

Receiver Sensitivity

1OuV for 50dB mono SNR with Wide IF.

Receiver Selectivity

Wide IF: -6dB at +-150kHz Narrow IF: -6dB at +-75kHz

Stereo Separation

Wide IF: >45dB (typically 50dB), 20Hz-15kHz. Narrow IF: typically 20dB, 20Hz-15kHz.

Distortion (in MPX or demodulated audio)

Wide IF: <0.3% THD. Narrow IF: <3% THD.

Composite Baseband (MPX) Output

Unbalanced output with 75-ohm source impedance IS adjustable between 2V p-p and 5V p-p at +-75kHz carrier deviation.

Output Mute Function (defeatable)

MPX and program audio outputs are muted when the incoming RF carrier level falls below 10uV

Stereo “Blend” Feature (defeatable)

Circuitry integral to the stereo decoder monitors noise in the upper baseband spectrum. Stereo program audio is proportionally blended to mono, minimizing noise in the demodulated left/right program audio output. (Does not affect the composite MPX output signal.)

Overdeviation Limiter

An internal clipping circuit limits the MPX output to a maximum level equivalent to +-100kHz carrier deviation.

Program Line Outputs

Left and right channel active-balanced outputs deliver OdBm into 600 ohms at +-75kHz carrier deviation

Frequency Response (program audio output)

+-0.5dB, 20Hz-15kHz. De-emphasis may be jumpered for 75uS or 50uS characteristic.

Noise (program audio output)

Better than 60dB below +-75kHz deviation with 1mV or greater RF input.

Remote Control Logic

Independent contact closures to ground will initiate forced-mono reception, select the narrow IF bandwidth, defeat the output muting feature, and defeat the “blend” function.

Fault Indicators

Front-panel indication of a low signal (mute level) condition, loss of program audio, and excessive multipath distortion in the received signal.

Remote Alarm Provision

Open-collector NPN transistor switches saturate to ground for a low signal condition and for loss of program audio.

Power Requirement

105-130VA C or 210-255VAC, 50/60Hz; 20W.

Size and Weight

1 3/4”H x 19”W x 6”D (1U): 7 Ibs.