VHF Systems for Reptiles and Amphibians

MOD-125, LB-60, LB-65 as designed for attachment to turtle or tortoise shell, and CHP-8P as could be implanted in a snake.

Reptiles and amphibians are a broad category of species that vary widely in size, form factor, behavior, telemetry attachment methods, and habitats used. This section addresses various VHF options. Satellite-linked units are also used for larger species, and they can offer tremendous advantages for tracking wide-ranging species such as marine turtles or for animals in remote areas where VHF tracking is difficult. If you have questions, please ask.

Turtles and tortoises usually have transmitters glued (or sometimes otherwise attached) to their shells, but implantable transmitters have also been used. These animals can vary greatly in size, so appropriate models depend on the species and size of animal being studied as well as study objectives. Various CHP, LB and MOD models as noted below have been used on turtles and tortoise. Satellite-linked systems are extensively used on marine turtles, and also have application on large tortoises (e.g. Sea-tracker GPS/Iridium, Argos/GPS, and Argos-only models).

Snakes are usually instrumented with implantable transmitters, which are either surgically implanted or fed to the snake. Telonics offers a range of implantable transmitters as appropriate for different sizes of snakes and other species. Alternatively, transmitters are sometimes taped externally. Taping and ingestion typically provide for shorter tracking times, with the animal self-ridding itself of the transmitter. Various CHP configurations (as described below or under implantable transmitters) are used on snakes both as implants and external taping. For large snakes other VHF transmitters such as the LB-60, LB-65, or MOD-050 (described below) or other models can be taped externally.

Lizards are instrumented with implantable transmitters, harnesses, and gluing. CHP models such as those listed below or under implantable transmitters are most appropriate for most species because of their size, though larger species can also use other models.

Toads and frogs have been instrumented using ingestible transmitters, surgical implants, and a variety of belts and harnesses. CHP models such as those listed below or under implantable transmitters are most appropriate for most species because of their size.

Crocodilians typically have transmitters screwed or otherwise attached to the back of the neck, though implantable transmitters have also been used. Models typically used on crocodilians are described in a separate section (VHF Systems for Crocodilians). GPS/Argos satellite-linked units have also been used on crocodiles, and the new SeaTrkr GPS/Iridium model would offer advantages for many applications.


CHP Models

The CHP series is designed primarily for small size and light weight. This entails compromises, and CHP transmitters have lower output power, performance more impacted at temperatures below ~0°C, and fewer sensor options compared to other Telonics VHF transmitters. Because of the type of batteries used to power these units, long-term storage (more than several months) should be avoided, particularly with the smallest models.

Model Dimensions
L x W x H (in, cm)
Unit Weight (g) Life @ 60BPM (months) Life @ 30BPM (months)
CHP-4P 1.0 x 0.8 x 0.6
2.5 x 2.0 x 1.5
13.5 19 28
CHP-5P 1.35 x 0.5 x 0.3
3.4 x 1.35 x 0.7
6.8 7.4 13.4
CHP-6P 0.9 x 0.5 x 0.3
2.3 x 1.3 x 0.7
3.7 3.7 6.7
CHP-7P 0.8 x 0.35 x 0.3
2.1 x 0.9 x 0.7
2.2 1.5 2.8
CHP-8P 0.8 x 0.3 x 0.15
2.05 x 0.8 x 0.4
1.2 0.5 1.0

Operational lives for listed for CHP models reflect operation 24-hours/day at 60 and 30 beats per minute at 20°C. Dimensions and weights indicated are for the transmitter electronics, power supply, packaging, and a lightweight ~6" whip antenna. Specialized attachments or alternate antennas might increase weights.

MOD Hermetically-Sealed Models

MOD series models are fully-hermetically sealed for maximum reliability, with the transmitter, battery, and interconnects sealed into a single metal housing. This is the same technology used by NASA for maintaining high performance electronics in harsh environments. With hermetic packaging, there is no problem with moisture penetration even after years of deployment, except in cases of severe physical damage to the canister. No polymeric packaging offers this level of reliability. These configurations are typically provided with the MK-12 transmitter electronics, but the MK-11 can alternatively be used (see below).

Model Dimensions
L x W x H (in, cm)
Weight (g) Transmitter Electronics Life @60BPM Standard Power (months) Life @60BPM Low Power (months)
MOD-050-2 2.2 x 0.7
5.6 x 1.8
30 MK-12 8.3 19.4
MOD-073* 1.3 x 1.1 x 0.4
3.5 x 2.6 x 1.0
22 uMK7 4.1 10.5
MOD-080-2 1.3 x 0.7 x 0.9
3.3 x 1.8 x 2.3
36 MK-12 9.1 21.2
MOD-105-2 1.6 x 0.9 x 0.8
4.1 x 2.3 x 2.0
45 MK-12 9.1 21.2
MOD-125-2 1.6 x 0.9 x 0.8
4.1 x 2.3 x 2.0
53 MK-12 13.5 31.3
MOD-210-2 1.7 x 1.3 x 0.7
4.3 x 3.3 x 1.8
75 MK-12 18.0 41.0
MOD-225-2 1.8 x 1.3 x 0.7
4.6 x 3.3 x 1.8
85 MK-12 22.3 50.5
MOD-335-2 1.4 x 1.4 x 1.1
3.6 x 3.6 x 2.8
105 MK-12 26.6 59.6

LB Models

LB models use the same electronics (typically MK-12, but alternatively MK-11) and batteries as the MOD series; however, the packaging is polymeric. These units still provide excellent water resistance, such that water penetration is not an issue within the expected battery life of these configurations. LB configurations typically offer an improved operational life to weight ratio as compared to MOD configurations.

Model Dimensions
L x W x H (in, cm)
~Weight (g) Transmitter Electronics Life @60BPM Standard Power (months) Life @60BPM Low Power (months)
LB-35-2 1.6 x 0.8 x 0.6
4.2 x 2.0 x 1.4
14.5 MK-12 4.6 10.8
LB-37-2 1.6 x 0.8 x 0.5
4.2 x 2.0 x 1.3
15 MK-12 4.6 10.8
LB-38-2 1.6 x 0.8 x 0.5
4.2 x 2.0 x 1.3
14.5 MK-12 4.6 10.8
LB-60-2 1.5 x 0.8 x 0.4
3.8 x 2.0 x 0.9
10.5 MK-12 1.9 4.5
LB-65-2 1.8 x 0.75 x 0.4
4.7 x 1.9 x 0.9
13 MK-12 4.6 10.8
LB-81-2 1.5 x 0.8 x 0.8
3.9 x 2.0 x 2.0
30 MK-12 9.1 21.2
LB-420-2 2.7 x 1.4 x 1.4
6.9 x 3.4 x 3.4
135 MK-12 35 76

Operational lives listed above for MOD and LB models are calculated using Telonics Product Programmer (TPP), with assumptions of 60 beats per minute and operation 24-hours per day at 10°C. Duty cycling can extend operational life, e.g. operation for an average of 12-hours/day can increase lives by ~90%. Reduced pulse rates can also extend operational life; e.g. use of 30 beats per minute rather than 60 bpm can increase life by ~90%. Operation for extended periods at lower temperatures will decrease operational life. The MK-11 electronics are also available in smaller configurations; however, such use would decrease estimates of operational life by ~10-15% with standard power and temperatures above ~0°C, and up to about 45% with low power options and lower temperatures (the MK-11 is not an option in the MOD-040 and MOD-050).

Key Features of MOD and LB series

  • MOD and LB models use either Telonics MK-11 or MK-12, both of which are microprocessor controlled transmitters which can be programmed using Telonics Product Programmer (TPP). The MK-11 has synthesized frequencies programmed through TPP; the MK-12 is crystal controlled. The MK-12 is most frequently used in smaller configurations because it provides longer life particularly at temperatures of ~0°C or below.
  • Customized transmission duty cycling (on/off periods) is available, including seasonal cycles which can vary throughout the life of the transmitter.
  • All timing is controlled by a Real-Time-Clock, which allows seasons to start and end on any desired calendar date and time and sensor data to be accurately time stamped.
  • MS6 mortality-motion option available at no additional charge.
  • Other sensor options are available, including the MA activity option, MS4 temperature option, and MS5 temperature-triggered mortality option (sensor descriptions are provided below). Data collection from these sensors is user programmable with Telonics Product Programmer (TPP).
  • Data Logging Option 350 is available to store mortality, activity, and/or temperature data in transmitter memory for download if the transmitter can be recovered.
  • Transmission power levels are selectable to accommodate either greater range or greater life (4 levels with MK-12 electronics, and 3 with MK-11).
  • The uMK7 transmitter electronics are a previous generation of Telonics electronics that have generally been replaced by MK-11 and MK-12 circuitry. The uMK7 continues to be used in the MOD-073 because of its specific dimensions. The uMK7 does not provide for on-board data logging, and some sensing options work somewhat differently as compared to the MK-11 and MK-12 electronics.

Key Features of CHP transmitters

  • These models use the µCHP transmitter.
  • The S2 Temperature Sensing Option is available with CHPs. This sensor provides a variable pulse rate dependent on temperature within the transmitter package. The user specifies a desired pulse rate at an anticipated median temperature and the approximate range of temperatures to be monitored. Pulse rate increases at higher temperatures and decreases at lower temperatures.

Data Logging Option (Option 350) for VHF Transmitters using MK-11 or MK-12 Electronics

The Data Logging Option for MK-11 and MK-12 transmitters (Option 350) allows sensor data from the MS6 mortality-motion sensor, MA activity sensor, and/or the MS4 temperature sensor to be stored in transmitter memory and made available for download if the transmitter is able to be retrieved at the end of a study. Additional information regarding how these sensors work is provided in the Sensor Options section below. This option requires use of Telonics Data Converter to download the stored data.

For the MS6 motion-mortality sensor, the data logging records each date and time the sensor switches from active/alive to inactive/mortality or back. Assuming that no other sensor measurements are being stored, the data log can accommodate about 0.5 million transitions. Note that smaller units may not have sufficient battery capacity to fill the memory. The most recent 9-16 such transitions are recorded even without this option, but this option stores all such transitions.

For the MA activity sensor, the data logging option stores accelerometer data at user-defined intervals. These intervals may be the same throughout the anticipated life of the transmitter or they may change "seasonally". The activity data recorded is the number of active seconds (or other defined classification interval) during a defined collection interval. For example the number of active seconds in a one hour collection interval would be saved as a number between 0-3600. Assuming that no other sensor measurements are being stored, the data log can accommodate about 2.0 million measurements based on 30sec, 1 minute, or 5 minute intervals or about 1.3 million based on longer intervals. The activity collection schedule for data logging is independent of any activity schedule selected to control pulse rate.

For the MS4 temperature sensor, the data logging option stores temperature data at user-defined intervals (in 0.16°C increments). These intervals may be the same throughout the anticipated life of the transmitter or they may change "seasonally". The data log can store an estimated 1.3 million measurements if no other sensor data are stored. The temperature collection schedule for data logging is independent of any temperature schedule selected to control pulse rate.

Specifications for Transmitter Electronics

MK11/12 Transmitter General Specifications

MK-11 and MK-12 beacons are microprocessor controlled pulsed-CW transmitters, designed for operation within the 137 - 225 MHz frequency range. Each MK-11 beacon transmits on a single, field-programmable frequency (within the frequency range that is ordered). MK-11 beacons also support 3 field-programmable power levels. The MK-12 beacon is crystal based, and therefore each beacon is built to operate on a specific frequency and with a specific power output (four power levels to choose from when ordering).

Frequency Range MK11:
137 - 143 MHz (option 700),
143 - 156 MHz (option 710),
154 - 164 MHz (option 720),
162 - 174 MHz (option 730),
164 - 182 MHz (option 740),
182 - 201 MHz (option 750),
201 - 222 MHz (option 760)

140 - 225 MHz
Frequency Tolerance MK11:
Calibration: ±3 ppm max at room temperature / ±5 ppm from -40° to +70°C
Aging: <1ppm/yr
Shock: <1ppm 3000g x 0.2ms x ½ sine x 3 directions

Calibration: ±17 ppm at room temperature / ±25 ppm from -40° to +70°C
Load: <7ppm typical for VSWR < 6:1
Supply Voltage: <3ppm typical over supply voltage range at 25°C
Aging: <1ppm/yr
Shock: <1ppm 3000g x 0.2ms x ½ sine x 3 directions
VSWR Stability MK11: RF output stable to 10:1 VSWR, all phases.
Radiated harmonic levels are degraded with poor load VSWR.
Spurious emission specification maintained for > 10:1 VSWR.

MK12: RF output stable to 5:1 VSWR, all phases.
Radiated harmonic levels are degraded with poor load VSWR.
Spurious emission specification maintained for > 5:1 VSWR.
Output Power
MK11: Field Programmable using TPP
Transmit Power Peak Power Output
Relative to Medium Power
Low 0.5 * Medium Power
High 2.0 * Medium Power

MK12: Ordering Options for Power Level
Option Transmit Power Peak Power Output Levels
Relative to Standard Power
200 Low (Temperature > -20°C) 0.5 * Medium Power (Higher efficiency)
202 Low 0.5 * Medium Power
204 Medium  
206 High 2.0 * Medium Power

Output power is measured into 50 Ω load. Effective Isotropic Radiated Power (EIRP) varies, depending on packaging, antenna configuration, and immediate environmental conditions.
Emission Designator MK11: 2k00P0N -
California users: These transmitters meet the California requirement of EIRP < 0.0009W for all conditions.
MK12: 1k00P0N -
California users: These transmitters exceed the emission designator requirement of 2k00P0N for operation in California. The 1k00P0N emission designator is identical to the 2k00P0N except that it occupies only half of the 2 kHz bandwidth allowed by the State of California for wildlife tracking.
Harmonic and Coherent Spurious Suppression MK11: <-30 dBc into 50Ω load
MK12: Coherent Spurious <-10 dBc
Spurious Suppression MK11: <-35dBc typical at > 10kHz offset from carrier
MK12: Non-Coherent Spurious <-50 dBc
RF Pulse Width 15 msec standard
Can optionally be configured from 10 - 250 msec
Pulse Period Configurable from 250 - 5000 msec (12-240 Bpm)
RTC Accuracy / Seasonal Timing Temperature Compensated:
± 12min/yr max
Temperature Range -40°C to +70°C (Note: Temperature range is for the transmitter only. The power supply must provide the required peak current and voltage requirements for the transmitter over the expected temperature range.)
Shutdown Component Externally shutdown by presence of a small magnet
Available Sensors
MS6 Mortality - Motion Sensor
MA Activity Sensor
MS4 Temperature Sensor
MS5 Temperature-triggered Mortality Sensor
Sensor descriptions available separately

µCHP Transmitter General Specifications

Frequency Range 140 - 220MHz (w/ 3rd Overtone micro-miniature shock crystal)
Frequency Tolerance ±7ppm max @ 25°C
±25ppm max -0 < Temp < +60°C
(<15ppm typical w/ 6:1VSWR variation - CHP-5P through -9P)
(Optional: <7ppm typical w/ 6:1VSWR variation - available only w/ CHP-4P)
(<5ppm typical over supply voltage range)
Temperature Range -20° to +60° for the electronics1
Power Control Component Externally controllable by presence of a small magnet.
Current Requirement 3.0mA typ peak ('on' state, during RF pulse
5µA typ quiescent current ('on state', between RF pulses)
<2µA typ with magnet in place ('off' state)
RF Pulse Width 15msec ±3msec typical at +25°C / 1.5V
(18msec±4msec typical at 1.1V)
(13msec±2msec typical at 1.8V)
Pulse Rate Configurable from 20 to 300 beats per minute (Pulse Period 200 - 3000msec)
Spurious Output Coherent Spurs <-10dBc
Non-coherent Spurs <-40dBc
Available Sensor Temperature (Thermistor): ~ 0.1°C resolution with calibration
Dimensions (bare board) Crystal Piggyback: 0.25 x 0.30 x 0.22in
Crystal End-Mounted: 0.25 x 0.49 x 0.09in
Packaging Application Dependent - typically polymeric

1. The defined temperature range is for the transmitter electronics only. Most small batteries used with the CHP cannot provide the required peak current and voltage below ~0°C. The battery used with the CHP-4P is suitable to -20°C.

Sensor Options for VHF Transmitters using the MK-11 or MK-12 Electronics

MK-11 or MK-12 Sensor Options

Related Products

Satellite-linked systems are frequently used on marine turtles, including:

Implantable transmitters are frequently used on snakes and lizards.

Lithium Battery Shipping Regulations

Telonics Inc. ships all systems containing lithium batteries in accordance with the US Department of Transportation rules for hazardous materials set forth in 49CFR and the IATA Dangerous Goods Regulations.

Shipping dangerous goods can be complicated and confusing, consult a dangerous goods specialist if needed. The general requirements for shipping lithium batteries according to 49CFR are located in Part 173, Subpart 173.185 in the link below.

Service Commitment

Since 1970, Telonics has built a reputation based on product quality, product support, service, and customer satisfaction. Telonics strives to produce the highest quality products, and to support those products accordingly.

Because of extreme conditions and the unpredictable nature associated with most telemetry applications, problems occasionally arise. Most problems can be resolved quickly. In all cases, we hope to be able to work in partnership with users to resolve problems to the user's satisfaction and to uphold our demonstrated commitment to excellence. If problems should arise, all products must be returned to our factory for failure analysis.

Warranty: VHF Transmitting Subsystems

The VHF Transmitting Subsystem includes the following main components: internal digital and radio frequency electronics comprising the transmitter, power supply (battery), exterior packaging, transmitting antenna and attachment. A refurbished Subsystem is warranted as if the Subsystem was purchased new, unless otherwise stated.

Telonics warranties only the following with respect to the Subsystem:
1.1 The internal electronics (excluding batteries) are warranted to be free from defects in materials and workmanship and to perform to the operational specifications over the specified operating temperature range as published by Telonics for the rated operational life of the Subsystem (as recorded on the final test data sheet accompanying the unit), up to a maximum of three (3) years from the date of initial shipment of the Subsystem by Telonics.
1.2 The exterior packaging integrity of hermetically sealed subsystems are warranted for the full operational life of the Subsystem, up to a maximum of three (3) years from the date of initial shipment of the Subsystem by Telonics.
1.3 The exterior packaging integrity of polymerically sealed subsystems are warranted for the operational life of the Subsystem, up to a maximum of one (1) year from the date of initial shipment of the Subsystem by Telonics.

Although each Subsystem is supplied with a power supply in the form of a battery, Telonics does not manufacture batteries (electrochemical cells), and therefore cannot warranty the battery lifespan, mechanical integrity or other battery performance issues. However, Telonics conducts extensive testing of all types of electro-chemical subsystems to determine suitability to the application. Once an electrochemical system is chosen for a configuration, testing procedures are employed at Telonics to evaluate every individual battery that is installed in each transmitting subsystem. Even using these advanced testing procedures it is not possible to determine a specific battery's lifespan or mechanical integrity.

Telonics conducts tests to assure that each unit is transmitting at the power level selected by the user. Actual range performance is a system characteristic dependent upon numerous conditions including receiver sensitivity and noise figure, receiving antenna tuning and pattern, transmitter antenna integrity, line of sight conditions in the field, and vegetation and habitat conditions and other factors specific to individual study sites. Therefore it is not possible to warranty a minimum range that will be achieved for units deployed in the field.

"Packaging integrity" as applicable to 1.2 and 1.3 above, is limited to normal wear as encountered on the animal.

It is the purchaser's obligation to make certain that it orders the correct size and type of Subsystem for the particular type and size of animal that the Subsystem will be applied to, and no warranty is expressed or implied for any failure to meet operational specifications due in whole or in part to use of an incorrect size or type of Subsystem.

No warranty is expressed or implied with regard to abnormal events or damage due to human actions such as gunshot damage, vehicle encounters, etc. Further, no warranty is expressed or implied with regard to damage resulting from misuse, accidents, unauthorized service, extreme conditions, or other causes not specifically enumerated herein.

The entire risk, as to the results and performance of the Subsystem, is assumed by the customer. Neither Telonics, nor its suppliers, shall have any liability to the customer or any other person or entity for any indirect, incidental, special, or consequential damage whatsoever, regardless whether Telonics has been told of the possibility of such damages or that such damages might be foreseeable. Telonics has no responsibility or liability for the claims of any third party. Telonics' and its suppliers' maximum aggregate liability shall not exceed the amount paid by the customer for the Subsystem.

Exercising the Warranty
If a defect occurs, return the Subsystem to Telonics within the applicable time frame noted above at the following address: TELONICS, 932 E. IMPALA AVENUE, MESA AZ USA 85204-6699. Telonics does not assume responsibility for loss or damage to equipment during shipment. Telonics does not assume responsibility for delays resulting from shipment on commercial or private carriers. We insure all equipment shipped from our facility and suggest that shipments to Telonics also be insured. Customer shall arrange for and pay all shipping, insurance and related charges incurred in the shipment of Subsystems to and from Telonics under this warranty.

Upon the timely return to our facility within the applicable time frame noted above, if the exterior packaging integrity and/or internal electronics (excluding batteries) are defective, the Subsystem will be replaced or repaired, at Telonics' sole discretion, at no cost to the customer, other than shipping charges. This remedy is the exclusive remedy. This product is supplied without any further warranties or conditions, expressed or implied, including warranties of merchantability, quality or fitness for particular reason or those arising by laws, statutes or trade usage or course of dealing.

The above warranty extends only to the original purchaser and does not cover any Subsystem which is resold or otherwise transferred from the original purchaser to another party. The warranty will be extended to customers who purchase the Subsystem directly from a Telonics-authorized distributor.