This transmitter was designed for tail mount attachment on raptors and other birds with robust tails. It can also be configured for backpack attachment to birds, herptiles and small mammals.


Model Weight Standard Life Lifespan range Dimensions: Diameter x L (mm)
RI-2C 6.0g 12 months 6-18 months 10 x 32
RI-2C 7.5g 18 months 12-18 months 10 x 39
RI-2C 9.0g 24 months 12-24 months 10 x 49
RI-2C 15g 30 months 18-36 months 14 x 43
RI-2C 21g 36 months 24-48 months 16 x 46

Frequency Range: 138 to 235 MHz.

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

Pulse Width (standard): 24 milliseconds (ms). Available from 22-30ms.

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.

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

Attachment: Small tubes are incorporated for passage of material to tie the unit to one or two tail feathers. Larger tubes are used for backpack attachment.

Antenna: Stranded stainless steel cable covered with a black nylon coating. Two layers of shrinkable tubing reinforce the antenna at its base.

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


Mortality (suffix “M”): The available delay is 12 hours. 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.

Activity (suffix “A”): Every motion event exceeding a preset range of angles generates one extra pulse between the normal pulses. This activity pulse is distinctively shorter (~12 ms) than the normal pulses. This option adds ~0.5g to the finished weight of each transmitter.

Temperature (suffix “T”): An increase or decrease in temperature results in a corresponding increase or decrease in pulse rate. At the standard settings, the pulse rate changes from ~15 ppm at 0°C to ~50 ppm at 40°C. Each transmitter is supplied with a plotted calibration curve. This option adds ~0.05g to the finished weight of each transmitter.

Position (suffix “P”): The pulse rate switches from ~24 ppm to ~50 ppm when the animal changes body position, pivoting the transmitter 10° or more from a preset orientation. This option adds ~0.5g to the finished weight of each transmitter.




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