RTU 292 Radio-Telephone Interconnection Unit

General Information

The RTU-292 is an automatic telephone interconnect unit for the connection of one tele- phone line with one radio. It offers the flexibility of several modes for manned or unmanned station operation.

When used in manual mode, first a radio-to- radio link is established. Then, using the telephone in the RTU-292, the operator places a call to the distant telephone that will be patched into the radio link. Once the distant telephone party is on the line, the opera- tor pushes a front-panel button to complete the patch to the radio link. The operator may communicate with either party using the unit’s handset, and may monitor both sides of the conversation with the speaker.

The RTU-292 contains auto-dial/auto-answer capability. This feature enables users to dial from any phone system through unmanned radio stations into other phone systems.


Technical Specification

Telephone Line Interface

Output Level to Phone Line

Nominally -9 dBm (adjustable -12 to -6 dBm in 3 dB steps).

Input Level from Phone Line

Nominally -9 dBm (adjustable -12 to -6 dBm in 3 dB steps).

Frequency Response

300 Hz to 3200 kHz + 2dB.

Output Impedance to Phone Line

600 Ohms.

VOX Sensitivity

16 ± 2dB below input level setting (-25dBm @ -9dBm level setting for example).

VOX Hang Time

11 second or 1.5 seconds, internally adjustable.

Hybrid Balance/Adaptation Speed (into 600 Ohms)

-30 dB over 300 to 3200 Hz bandwidth within 1.25 seconds; measured witha white noise source.

Ultimate Hybrid Balance (into 600 Ohms)

-50 dB typical over 300 to 3200 Hz bandwidth; measured with a single tone.

Hybrid Impedance Matching Capability

0 to infinity Ohms complex impedance.

Phone Line Connections

RJ-11C connector (J1) and screw terminals.

Radio Interface (P1, DB-9 Male)

Input Impedance

Balanced or unbalanced 600 or 56k Ohms.

Input Level

-20 to -10 dBm, internally adjustable.

Output Impedance

600 Ohms, balanced.

Output Level

-20 to -10 dBm, internally adjustable.

Frequency Response

300 to 3200 Hz ± 2 dB.

Key Relay Output

Low level relay contacts, 60 VA max. Switching speed 5 msec.


Handset (RJ-12C Jack)

Electret microphone, dynamic receiver.

Dialing Modes

DTMF, pulse at 10 or 20 pps.

Pulse Dial Make/Break Ratio


Dialing Keypad

3 x 4, standard telephone layout.


Microphone Interface

ALC (Automatic Level Control) having 30 dB dynamic range.

Headphone Interface (Monaural Phone Jack)

Drives high, medium, or low impedance headphones. Delivers not less than 10mW into 600 Ohm headphones.

Speaker Driver Power

4 W min. @ 10% distortion.

Internal Speaker

3 inch square, 3.2 Ohms.


Indicators for each push button, plus peak level and keypad LEDs.

Front Panel Controls

Power on/off switch, Dialing keypad, Speaker volume control, Phones volume control. Pushbuttons: Tel-Line-Phone. Tel-Line-Radio, Handset-Phone, Handset- Radio, Speaker-Phone, Speaker-Radio, Tel-VOX, Manual Key, Auto Ans., Auto Ring.

DC Input Power

+11 to +15 VDC or +22 to +30 VDC, 1A maximum.

AC Input Power

115 or 230 VAC ± 15%, 47-63 Hz, 20 VA typical, 50 VA maximum.


3.5”H x 19”W x 10”D (6.9 x 48.3 x 25.4 cm).


12 lbs. (5.5 kg).

Operating Temperature

-25 degrees C to +55 degrees C.

Storage Temperature

-40 degrees C to +85 degrees C.


Up to 95% @ 55 degrees C.


MIL-STD-810D, method 516.3 procedure VI.


Radio remote control, VMR/noise reduction, Local phone, ALE control, Voice prompts, DTMF telephone.


MIL-STD-810D, method 514.3 category I.



-Command and Control Vehicles

-Tactical Site Communication

-Transportable Communication Platforms

-Command and Control Centers

-Emergency COmmunication Centers

-Desert Communication Solution




 RTU-292 brochure