631 Second Generation FM Receiver

List: $1,800.00


SKU: INO-63100 Category:


631 – Professional FM Relay Receiver


Inovonics’ Model 631 is our second generation of frequency-agile, digitally tuned receivers for FM translator and other critical off-air reception applications. Featuring menu-driven access of display and function selections, the 631 provides a switchable IF bandwidth to help solve difficult adjacent-signal problems and readouts of signal strength and multipath distortion to aid antenna alignment. Selectable options and alarms may be remotely controlled or monitored, and high-resolution bargraph readouts give accurate indications of incoming RF and MPX/stereo audio levels.



  • Easy to set-up and use
  • Selectable wide/narrow IF bandwidth
  • Composite/MPX and balanced L/R stereo outputs
  • LCD Display
  • Menu-driven selection of functions and readouts
  • High-resolution bargraph displays indicate: ◦MPX and audio levels ◦Total carrier modulation ◦Left/Right audio levels ◦Incoming RF ◦Multipath distortion
  • Digitally-tuned
  • Carrier-loss and audio-loss alarms


Tuning Range
87.5 –108.1MHz in 100kHz steps.

Antenna Input
75-ohm, ‘F’ connector (50-ohm option with ‘N’ connector available).

Receiver Sensitivity

  • MONO: 10µV for 60dB S/N
  • STEREO: 150µV for 60dB S/N


Receiver Selectivity

  • WIDE: –6dB at ±140kHz
  • NARROW: –6dB at ±80kHz


Distortion (in MPX or L/R audio)

  • WIDE: <0.2% THD
  • NARROW: <0.6% THD


Stereo Separation

  • WIDE: typ. >40dB
  • NARROW: typ. >20dB


Composite/MPX Output
Unbalanced, 75-ohm BNC; adjustable between 2V p-p and 6V p-p at ±75kHz carrier deviation.

Over Deviation Limiter
An internal clipping circuit limits the MPX output to a maximum level equivalent to ±100kHz carrier deviation.

Program Line Outputs

  • Left/Right active-balanced XLR outputs deliver +4dBm at ±75kHz deviation.
  • Frequency response ±0.5dB, 20Hz–15kHz
  • de-emphasis set by internal jumpers to 75μs or 50μs.


Low-Signal Muting
Composite/MPX and L/R audio muted when incoming RF falls below the user-programmed LOW-SIG level.

Audio Loss Alarm
Responds to loss of either stereo channel; alarm delay is user-programmable between 5 seconds and 4 minutes.

Fault Indicators
Front-panel LCD indication of low incoming RF or loss of program audio. Open-collector NPN transistor switches enable remote alarm indication via rear-panel terminal strip.

Power Requirements
105-130VAC and 210-260VAC; 50/60Hz; 20W

Size and Weight

  • 23” x 16” x 2” (2U); 8 lbs
  • 584mm x 406mm x 51mm ; 3.6 kg