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The units shown here:
AN/URT-33 (1983*)
AN/URT-33A (1982*)
AN/URT-33C (1984*)
AN/URT-33C/M (1987*)
AN/URT-33B-1
are Emergency Locator Transmitter (ELT), or "radio beacon"
Here you see five different versions of AN/URT-33.
The device normally is activated at bailout and sends a signal for quick location of the pilot.
A tone oscillating between 300 and 1000 hertz is sent two times a second.
AN/URT-33 is used for locating the pilot, the pilot talks to the rescue team by help of his SAR radio.
There are two disadvantages:
The constantly sweeping tone jammes the frequency;
The beacon can be pinpointed by the ennemy.
The picture gallery shows the development up to integrated circuits.
The year of issue is not known to me, the (*) refers to labels "replace battery".
The aging ELT or radio beacon are replaced by:
Emergency Locator Transmitter (ELT) with three frequencies:
(121.5; 243; 406 MHz).
The aging SAR- radios (like PRC-90) are replaced by:
Personal Locator Beacon & Voice Transceiver (PLBVT), with the same
three frequencies as ELT.
Technical Data:
- Frequency:
- 243 MHz, crystal controlled
- Output power:
- Continuous operation for 3 hrs : 150 mW
- Controlled operation for 15 hrs : 200 mW
- Range:
- 180 Miles, the SAR aircraft at 10.000 ft
- Modulation:
- Pulse carrier
- Frequency sweeping from 1000 to 300 Hz 2 times a second
- Activation:
- automatic, manual override
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AN/URT-27
MR-506