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Catering to the long felt need of the railways for a handheld portable emergency telephone we have developed a handy, light weight telephone for use of field staff on the emergency circuit to communicate with the controller at the head quarter in both 4 wire and 2 wire areas. Being lightweight and handy it can easily be made part of the fixed equipment of the locomotive. The telephone is housed in a sleek metal case for rugged operation and is provided with a convenient carry case with a shoulder strap. It uses dynamic capsules for the Transmitter and Receiver. Care has been taken to minimize the size and weight of the phone for ease of operation.
The telephone can work from 2AA size (pen cell) batteries and has amplifiers on both the trans and receive lines to achieve optimal speech and low insertion losses. Use of dynamic capsules enhances the speech quality and also increases the operational life. To minimize the drain on the batteries a push button type POWER ON switch is used. The switch is to be pressed whenever the telephone is in use. As soon as the switch is released the power to the telephone is cut off to prevent any battery drain during storage/transit.
The trans and receive lines are brought out through a 1.5 meter 4 way flexible PVC cord which can be terminated on a suitable plug to connect to a way side emergency telephone socket. The 2 wire lines can be connected to the telephone by means of 2 binding terminals on the telephone. A slide switch is provided at the bottom of the telephone to switch the telephone between 2 wire / 4 wire operation.
| Tummala Product Code: | TEL/PET/2W-4W |
| Frequency Response: | ± 3dB from 300Hz to 3Khz |
| Power supply Voltage: | 3V DC (2 AA size cells) |
| Current Drain: | < 10 mA (Max) |
| Size: | 205 x 60 x 55 mm |
| Weight: | 700 grams (including batteries) |
4 Wire Mode:
| Trans O/P with 5mV input: | > 0dB @ 1120 Ohms |
| Side Tone: | --- |
| Receive O/P: | > 100 mV (193mV I/P) |
| Insertion Loss: |
Transmit: < 1dB Receive: < 0.2dB |
2 Wire Mode:
| Trans O/P with 5mV input: | > 0dB @ 600 Ohms |
| Side Tone: | < 100mV |
| Receive O/P: | > 100 mV (193mV I/P) |
| Insertion Loss: |
Transmit: < 0.8dB Receive: < 0.2dB |