Model 251 DC Remote Base Station Adapter

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Model 251 DC Remote Base Station Adapter

DC Remote Base Station Adapter

Zetron’s Model 251 adapts most E&M/Local control devices, such as consoles or desktop remotes, to convert them to 2 or 4-wire DC Remote Control to control a DC remote fixed radio station. When used with the Zetron Model 250 Tone Remote Adapter, the combination may be used to convert tone remote control devices to DC remote control. The Model 251 supports up to 15 binary I/O or serial controlled DC currents in the range of +/- 0 to 15 mA.

Product Features and Configuration 

  • E&M/Local to DC remote control conversion
  • Tone remote to DC remote conversion when used with the Model 250
  • Up to 15 programmable currents in the range of 0 to +/- 15 mA
  • Supplies up to 125 V circuit voltage for up to 8000 ohm loops


Power: 10.8 to 16 Vdc, 520 mA max (250 mA typical idle)
Temperature: 32°F to 140°F (0°C to 60°C), operational
Size: 5.5” (140 mm) W x 8.25” (210 mm) D x 1.75” (45 mm) H
Weight: 1.4 lb (0.63 kg)
Control Circuits
Input voltage: 500 ohms or less to ground or +12 Vdc
will activate. Input range is 0 to +15 Vdc.
+5 Vdc open circuit voltage.
Input current: < 1 mA is inactive. > 3 mA is active. 40 mA max.
Busy Output: Contact closure to ground, +5 Vdc or +12 Vdc, jumper selectable
Alarm Output: Contact closure to ground
Serial Ports: EIA/TIA-574 9-pin female connector with
RS-232 signals used for configuration.
A second serial port may be used for real-
time control by an attached console
Audio Circuits
Isolation: Adapter logic/ground-to-Base station line - 2500 Vrms.
Console Tx line-to-Base station Tx line - 1200 Vrms
Console Rx line-to-Base station Rx line – no isolation.
Impedance: 600 ohms nominal
Insertion Loss: 2-wire/4-wire Tx – 2 dB max.
4-wire Rx – 0.2 dB max.
200 to 4000 Hz, -30 to + 10 dBm
Distortion: 0.5% maximum, 300 to 3000 Hz, 0 to 15 mA
DC Loop
0 to 8000 ohms
DC Loop
current range:
0 to +/- 15.5 mA in 0.5 mA steps
DC Loop
current accuracy:
3% or better
DC Line voltage: As required to maintain programmed current, up to 150 Vdc max
DC voltage input – approx 9.7 Vdc. Internal DC voltage output –
approx 116 Vdc


Model 251 - DC Remote Base Station Adapter - Remote Control