These transmitters are designed to be mounted in the ear of large mammals such as bears, deer, bison or hippopotamus.


Model Weight Standard Life Lifespan range Dimensions: L x W x H (mm)
EI-2 30g 12 months 6-18 months 44 x 44 x 18
EI-2A 55g 24 months 24-60 months 61 x 47 x 27

Frequency Range: 138 – 235 MHz.

Transmitter: Crystal controlled two-stage design pulsed by a CMOS multivibrator.

Pulse Width (standard): 24 milliseconds.

Pulse Rate (standard): 40 pulses per minute (ppm). Available from 20-120ppm.

Power Output: Set to use available battery power over the required transmitter life.

Activation: Removing an external magnet starts the transmitter. Replacing the magnet stops the transmitter.

Attachment: The transmitter is placed in the cup of the ear. The 1/4″ x 20 threaded nylon stud is passed through a hole in the ear and secured with a fabric washer and nylon nut.

Housing: The battery and transmitter are encapsulated in an inert waterproof epoxy.

Antenna: A loop within the epoxy encapsulation.


Mortality (suffix “M”): EI-2A only. The available delays are 4 or 12 hours. The 4 hour delay circuit indicates its activation by a double pulse. The 12 hour delay circuit indicates its activation by increasing the pulse rate from a nominal ~42 ppm to ~75 ppm. After the mortality mode has been triggered, any motion resets the transmitter to the normal pulse rate. This option adds ~0.5g to the finished weight of each transmitter.