7.3 mm ID tags

The Thelma Biotel 7.3 mm Acoustic Transmitter was originally designed for use with salmon smolt and is perfectly suited for small species where size is a limiting factor. The transmitter is suited for both manual tracking and automatic monitoring. The 7.3 mm transmitter has enabled researchers to study migration of wild Atlantic salmon smolt down to 13.5 cm in length and for periods in some cases up to one year of tag lifetime. It can be delivered both as Continuous Pingers and as ID Transmitters. The customer specifies pulse delay or coded ID, type of encoding, transmitting frequency and the average delay for ID transmitters. The tags are not just compatible with our own receivers (TBR 700), but can operate on standard code-sets (69 kHz) used by other equipment producers. 

Contact Thelma Biotel for help or questions regarding specifications.


Physical properties of 7.3 mm Acoustic Transmitter
Diameter [mm] 7.3
Length [mm] 18
Power output [dB re 1 uPa at 1m] 139
Weight in air  [g] 1.9
Weight in water  [g] 1.1



Battery Lifetime for Coded Transmitters

Avg. transmit



6 pulse code

battery life

7 pulse code

battery life

8 pulse code

battery life

Est (norm). Guar.* Est (norm). Guar.* Est (norm). Guar.*
120 282 169 261 157 243 146
90 243 146 222 133 205 123
60 190 114 171 103 156 94
30 115 69 101 61 91 55

 *As batteries will vary in capacity with temperature etc, the lifetime is guaranteed to a minimum of 60% of the normal average operating time. 

Battery life for Continous Pingers

Pulse delay 


1000 2000 4000
 Est.  Guar.  Est. Guar.   Est. Guar.
 Life [days]  57  33  77  45  124  75