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RT UHF Transmitter

RT_logosilver finalThe new RT UHF is a higher power transmitter running on the frequencies of 433-434 MHz. These frequencies require a receiver to match, which are also now available from Marshall Radio. Key advantages are that the antennas are much shorter while the interference and static caused by Commercial interference is almost non-existent.

 Built around the reliable 1/3N lithium battery, the RT UHF is the ideal shape and size for leg mounting. With the new bullet lid and tailspring added, it becomes a great TrackPack mount.

Please call for special pricing and lic. requirments.

Key Features


Current technology LED's are extremely efficient and require very little power.

Multi-color allows the LED to indicate more than just operation:

- GREEN = regular power and operation

- YELLOW = Low Battery Mode, time to change the battery

- RED = Bad battery, do not use


“All other features come second to reliability” For the RT UHF, it’s at the top of our list. Everything from the 54 components selected and used in this stable new circuit (some parts have an average rated life of 300 years!), to the processes used in the manufacture (surface mount technology) to the mechanical design makes it the most rugged design possible.


The crystal-based oscillators of the past have always been vulnerable to failure through crystal breakage when used as a leg mount on hard-hitting birds. Using new generation surface-mounted high-shock oscillators, the risk of having your transmitter fail from a fractured crystal has been reduced to near zero.


Tune in once and the signal is always there, same pitch, same sound. This transmitter circuit automatically adjusts to changes in its environment. In addition, temperature and voltage compensation handled by the circuit guarantee you always hear the same tone in extreme environmental changes.


Operating at the UHF frequencies requires only six inches to be full length and therefore, full power.


With the Magnetic On/Off switch, batteries can be left inside the transmitters, until they need to be changed. To turn it on, you simply hold the magnet to the lid or body of the transmitter until you hear three rapid beeps, which tells you the transmitter is on and running. You do the same thing again to turn it back off. This means transmitter can be left on the bird, such as a bird touchy to tail mounts, and then be turned on again just prior to the flight with the tap of the magnet. Tap-on just before flight; tap-off after picking bird up again. This new convenience does not add any risk to the reliability of the design, as it’s fault positive, meaning, if it should fail for any reason, the transmitter is left on. Also, if the magnet is lost, the transmitter can still be turned on and off manually as before.


No more having to ‘test batteries’ with a battery-tester before each flight to see if they are nearing the end of their useful life. The transmitter does all this for you: you get a double-beep on every fifth pulse indicating it’s time to change. And, when you first hear the low battery warning, you still have a 3-4 day reserve to look for a lost hawk.


We’ve found a way to again improve on the efficiency of the circuit, giving the most power output while barely sipping power from the battery thus extending it’s life as long as possible. Using the latest generation of field effect transistors and dynamic resonance circuitry, this new design pumps more energy into the antenna without wasting as much power through internal resistance. The result is the highest efficiency ciruit available anywhere.

Intended Use

This transmitter is best used as the rugged tarsus mounted transmitter in combination with a PowerMax or Micro on the tail or BackPack Harness. When ordered as a lag mount, the Bewit slot lid is standard.

Using the wire-clip design, and combined with the new Bullet Lid shown in the image, the RT UHF can be mounted to one of the deck feathers of a large falcon or hawk, or to the TrackPack on birds the size of a tiercel peregrine as seen uunder the Gallery Tab.



Q & A

Why do you use a metal case for your transmitters?
The machined aluminum casing provides superior protection. The strength to weight ratio of aircraft aluminum is just better than anything else, and the internal components are shielded from outside RF interferences as well. The screw on lid was designed to let you avoid having to handle the battery every time you turned it on or off and to keep water away from the battery and battery contacts. It also eliminates the risk of a lost hawk tearing off plastic tubing or electrical tape used on the older designs and removing the batteries.

I've heard of people having their transmitters come unscrewed during flight with a canister designs used as a leg mount. How have you solved this on the RT?
This can certainly happen if the the lid is not screwed down completely. Some people have been told by other companies not to screw down the lids too tight on other canister designs or they would void the warranty. This, and their incomplete lid assemblies, has led to a more than a few birds coming back with only the lids attached.

With the RT, this will not happen. Our internal gold washer spring has six small prongs that provide very strong back pressure for a lock-washer effect. The RT body and lid are machined so that you cannot over-tighten it. There is no flex or damage to the circuit board by screwing it down too tight. Simply screw it down 'till it stops, then push the lid and body together and tighten some more. It will then not come unscrewed on its own, through normal use on a bird even if it was left out for 100 years.

Another key mechanical improvement: our gold springs are made from beryllium copper that is chemically etched (not stamped) to very tight tolerances of a thousandths of an inch. These are then precision formed into the right spring shape here by us, heated-treated at very high temps for 4 hours, and then gold-plated for best possible conductivity and corrosion resistance. Also new for the RT is the direct battery connection through just the spring (not the lid). And the spring is now surfaced-mounted (machine-soldered) for maximum reliability.

Is the magnetic switch reliable?
Yes. We use a solid state Hall effect switch (a quantum magnetic device) that allows you to just hold the magnet to the transmitter for a second to turn it on and off. We've also perfected a way to use this neat little switch without an appreciable increase in battery drain, even if left in (and turned off) for months.

What are the best ways to mount the RT?
For those still using leg (tarsus) mounts on medium to larger sized birds, the RT is the ideal shape and choice. Built around the venerable 1/3N lithium battery, it provides a highly reliable secondary or backup transmitter. However, with the addition of the magnetic tap on switch, and the new Bullet Lid, it also works well with the TrackPack as shown in the Image Gallery.

What kind of range might I expect from the RT?
We've hung these transmitters up out in Wendover Nevada and received a good signal line-of-sight back in Utah at the top of Francis Peak, some 115 miles away. But the important measurements are on the ground and in actual hunting terrain where there are obstructions and other conditions that adversely affect the signal. And in every situation that you'll encounter, the RT will readily and clearly outperform other transmitters in the US market, excepting of course, the PowerMax.



For American (US/Canada/Mexico) Customers who have a HAM License, we can make sure you comply with the requirements of using this band by programming your Call Sign into the transmitter. Your Call Sign will be broadcast in Morse Code at startup and once every ten minutes as required by Law.

If you do not have an Amateur Radio License, you might be surprised how easy it is to obtain one. Pass a simple test, for which you can study all the answers in advance, pay ten dollars and with and 80% passing grade, you have a ten-year license, new knowledge about Radio Telemetry and the authorization to use the non-commercial bands (such as 433-434) not only for tracking but communication and emergencies.

For those wanting to find out what's required to get a HAM License, here's a great place to start: How to get your Amateur Radio License

Configure Your Product
Mounting Method Frequency Band if you need a specific channel, please specify during checkout Custom Engraving Text
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i.e. "Reward 555-555-5555"
Price with discount $350.00
Sales price $350.00
Sales price without tax $350.00