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PowerMax Transmitter


The PowerMax is the ideal transmitter for the backpack mounting method using the TrackPack. Its exceptional power output makes it the right choice as a primary transmitter while the flat coin-shaped case keeps a very low profile on the back. Mounted up higher on the bird, the nine-inch long antenna does not extend past the tail. Furthermore, it's been designed to be easily left on at all times and easily turned on or off with the tap of a magnet for daily use.

The PowerMax incorporates a low-battery indicator, you might think of as a fuel guage, that uses both a timer and internal voltage sensor to warn you in advance when it's time to change the battery. Accumulated run-time is approximately 60 hours with another five days left to search after the double-beep.

Combining a Powermax as your primary transmitter, with a small Micro transmitter on the tail as the backup, provides you with two dorsal mounts that are up high, flat and aerodynamic, and out of the way. It takes a matter of seconds to Tap both transmitters to life with the Mag Switches and be ready to fly.

Each unit is burned-in, tested for power and Enviro-tested tested from +150F down to -40F prior to shipping.

Available frequencies: 173, 216, 218.

Key Features


The PowerMax has about double the range and distance of the RT+. Like any transmitter, the range varies with terrain, but tests have given distances of 10 to 80 miles in the open deserts of the western United States.

This makes it the right choice for your primary transmitter used to track down a bird in adverse situations. Our engineers also implemented a unique design into the circuit that maintains high power levels even as the battery drains, or as the temperature drops and the battery current follows suit. You can count on the PowerMax signal all the way through the life of the battery.

Signal range will depend on the height of the transmitter, the height of the receiver as well as the type of terrain and obstructions.


Designed to hug close to the body, the PowerMax often dissapears below the large body contour feathers on the back of the bird after a vogorous rouse. Approach a bird that's been sitting comfortably on the block and it's likely you will not see it at all. The importance of a low profile design is serious at the high speeds experienced by most longwings, but just as important is for the bird moving through deep undergrowth or thick cover during a chase.


Over ten years ago, Marshall Radio pioneered the implementation of the Tap-On/Tap-Off magnetic switch. Magnetic switches at that time, where they existed, still required the transmitter to be removed and a large magnet held against the transmitter while stored away to keep it shut off. This saved the user having to untape and remove the battery every day just to turn the transmitter off each time, which was a step forward for the old brass battery contact designs back then.

The Tap-On was the logical next step forward in convenience, and together with the aluminum case designs and screw-on lids of today where the batteries are protected, it's now become a standard option on all Marshall transmitters. Many falconers just leave the transmitter mounted on their bird at all times, since there's no tape or rubber sleeve for a bored falcon to tear off, and then "tap" it on just before the flight. No fight getting the transmitter mounted, no conflicts or battles just before turning a bird loose. You only need to remove the transmitter once a month, or less, to change the battery.


After accumulating approximately 60 hours of actual run time, the normal single beep of the transmitter changes to a double beep every tenth pulse, letting you know that it's time to change the battery. Even though a transmitter switches to Low Battery Mode,  there's still five days of back-up time left to look for a lost bird. The transmitter runs at the same power levels but it simply warning you to change the battery.

You should get into the habit of changing the battery every time you hear the double-beep. If you were to fly your bird right before the double beep warning began, and the bird became lost, you would have about five days or so to search for it. If you continue using the transmitter into the Low Battery Mode, you will have an uncertain amount of time (much less) to look for it and will be at risk of not knowing, guessing at the amount of run-time left as with older designs still in use.

In addition to the 60 hour timer, the PowerMax monitors battery voltage, and will warn you with a double beep if you put in a weak battery.


This unique feature gives you the most time to find a lost bird. If the PowerMax is not turned off for 16 continuous hours, it figures your bird is probably lost and takes actions to conserve battery life with shorter and less frequent pulses. Under normal use at high power and regular duty cycles, a new battery should provide about 7-9 days total time. If you lose your bird with a fresh battery, the Apollo 13 Mode will double the normal life of the battery.

Intended Use

The PowerMax is the ideal transmitter for the backpack mounting method using the TrackPack because of it's shape and size. Its exceptional power output makes it the right choice as a primary transmitter while the flat coin-shaped case keeps a very low profile on the back of the bird. The nine-inch long antenna does not extend past the tail.

The BackPack method allows a bird to carry a large transmitter than would be reasonable on the lag or tail, yet the PowerMax weighs the same as the RT+ legmount. But even a light transmitter should not sit high or extend high above the back for obvious saftey reasons.

Furthermore, it's been designed to be easily left on the bird and easily turned on or off with the tap of a magnet for daily use, and the placement up high between the shoulders makes an easy target for the falconer to tap with the magnet. The backpack mounting method is now widely used by thousands of falconers through the US and Europe as well as South Africa. Reasons for this are: safety for the bird, best performance for the transmitter and ease of use for the falconer.

(see the "BackPack" Tab under Mounting Methods near the top of the Transmitters Page)

The PowerMax is also well designed to be a flat, tail hugging tail mount where a nine-inch long antenna will not extend more than a few inches beyond the deck feathers. With a total weight of 8.9 grams (including battery), it would be recommended for the larger birds  (female peregrine and up) only.

Customers Say

davecherry"I take my falconry very seriously and consider Marshall to be the only telemetry I trust to do the job. The PowerMax is so advanced, so well designed, I love it. I don't have to do battle with my bird just before the flight. Instead, I just leave the transmitter on and then tap it with the magnet and check it on the receiver and he doesn't know anything's happened."
"And the new, more flexible springs are great. Even easier to get on and off."
Dave Cherry, California



julio"A mi me gusta muchisimo lo que han hecho con el 'PowerMax.' Es lo mejor que hay. Y tambien, puedo usarlo con mi peregrino macho."
Julio Cesar Perez, Espana





"I have had excellent results using PowerMax transmitters; the design is great! I really like their short antennas as they greatly reduce the likelihood of electrocution and/or "wrap-ups" that can occur when a falcon is hard after difficult quarry both in the air and on the ground. I have had decks pulled out in the past when using tail mounts, and while there is no abolute fail-safe, the low profile of the power max certainly helps reduce that possibility. PowerMax transmitters have helped me recover gyrs and gyr hybrids on numerous occasions when I was in areas not accessible by roads but with enough hills and gullys that a bird on game could have been easily lost.

Sometimes I daydream about how we kept from losing our birds in the days before telemetry, let alone before high quality transmitters like the powermax. Well, I guess we didn't."
Steve Sherrod, Oklahoma


djknutson"I spend a considerable amount of time and effort developing my gamehawks and over the years find myself traveling to various areas of the USA to pursue many of the most difficult upland quarries that can be found. Most recently I have been traveling across the border into Canada to hunt their finest quarries and I put a lot of thought into assuring that I will bring all of my hawking partners home with me. The last thing I want to do is lose and have to leave one of my partners behind.


"For several years now I have trusted PowerMax transmitters on each of my birds (tailmount) as well as a legmounted RT+. Throughout the hawking trips I leave the PowerMax's on the birds, turning them on / off with the touch of a magnet."

I also use a Field Marshall reciever and have been impressed with it's reliability as well as its ease in operation. Thanks goes to Robert and his dedicated crew at Marshall and I look forward to their new innovations and product improvements."
DJ Knutson, Washington



ralphrogers"My year consists of a June hack site, followed immediately by falconry season and government winter/spring surveys for grouse. Between the dogs, hack falcons, and falconry birds, I use Marshall equipment every month of the year but May. It has great range and more importantly, does its job with fantastic reliability."

"I really appreciate you guys making the efforts to give falconers so much more in terms of high quality telemetry."

Ralph Rogers, Montanna


"I fly in open rolling sandhill most of the time. I am truly happy using the PowerMax for several reasons. The short antenna (most important feature on a tail-mount) makes it safe. The packaging of the unit makes it ideal for use on large falcons, and it's simple to leave on the bird, turning it on with a magnet. And, any small problems that I have had, have always been serviced in a short turn around and all my questions have been answered in a prompt manner."
Ed Fitch


    Q & A

    My bird threw up quickly from a very fast stoop and pulled out a feather.  Does this happen often?

    Not often, but it has happened, and it only requires one time to be a disaster if for some reason the follicle is permanently damaged and the feather does not grow back. Some falconers have been able to save the follicle with quick thinking: they cut of the top of the quill from the lost feather and reinsert it into the now open plug, securing it with a tiny drop of superglue. This keeps the follicle from being permanetly damaged through drying out and scarring. This little plug is dropped later during the molt, when the replacement feather comes in. We have heard of others simply applying Vaseline to the open follicle to protect it and let it heal, and a replacement feather grows back prior to the molt.

    When you consider that a hard hitting falcon can pull up to 26 G's at the bottom of the stoop, an 8.9 gram transmitter can suddenly weigh over 8 ounces for a split second! That's a lot of pressure for a single feather to support.

    However, with the advent of the backpack, it's now possible to take all the advantages of the PowerMax and move it up about five inches using a mounting method that is now proven safe, secure and allows the weight of the transmitter to be distributed more broadly. This temporary higher weight during the throw up is now behind the body, and in direction of the stoop, through the harness.

    The Micro is one third the weight of the PowerMax, at only 3.5 grams with battery installed. Combine that very light weight with the steady improvements in power and efficiency in the Micro, and you see why it has become the preferred transmitter for tail-mounting.

    Therefore, if you are flying birds 600-700 grams and below, we recommend using the 3.5 gram Micro as the ideal tail mount, and nothing heavier.

    I put in a brand new battery, but it's still double-beeping.

    This can happen when replacing batteries due to the internal timer not being reset. It's important to remember that the PowerMax has internal memory which keeps track of the total run time for each battery. The transmitter "remembers" its state from the last time the battery was removed, since the timer is kept activated by the remaining charge inside its bank of tiny capacitors.

    To clear this memory when a new battery is installed, you can put it in backward for a moment (positive side facing transmitter) which will short out the two electrical conections, and then put the new battery back in normally. This instantly dissipates the remaining charge left in the transmitter and resets the timer. Using the upside down battery to do this makes it simple.

    Also, the timer will automatically reset (remaining charge in the transmitter will dissipate to zero) if you remove the battery and let the transmitter just sit empty for 10 minutes.

    Why are there two types of Springs?

    The original spring material was a heavier gauge and had longer hooks. This helped the PowerMax stay on secure and be nearly impossible for a bird to remove. However, it was also more difficult for some falconers to remove, so we designed a second lighter spring with slightly shorter hooks that solved this problem for them. Some prefer one over the other, and they are interchangeable but the standard spring is now the lighter one.

    How much can I trim the antenna without losing a lot of range?

    The antennas on all Marshall transmitters have been carefully tuned to the optimum length. If an antenna is cut down (significantly) from the length it was sent with as standard, drastic loss of range can occur.  Significant shortening of an antenna may also cause other un-intended side effects, so it is not recommended.

    How do I replace the antenna myself?

    You will find a short "How-To Video" under the Training Videos Menu on the home page to take you through the process one step at a time.

    How does extreme cold affect the 1632 coin cell batteries used in the PowerMax?

    If you are planning to fly in very cold conditions where a bird may become lost overnight, you should always use a new battery. As coin cell batteries run through their life cycle, they lose some of their ability to provide current o run the transmitter in very cold temps. While the CR1632 battery will work at truly arctic temperatures for the first 36 hours of its life, after 72 hours it may not operate below -20C (0F) and subsequently will require even warmer temperatures.

    What is involved in reprogramming the frequency to another channel?

    To be able to electronically change the frequency on your transmitter is still a feature that is still not available from any other company, six years after we first pioneered the concept. You can have your PowerMax's frequency changed to any other frequency (within the bands it's designed for, i.e. 173, 216, 433 etc.) whenever, and as many times as you want.

    Also, the pulse width and the pulse rate can be adjusted up or down from the default settings to give you either better battery life or more longer, easier-to-track pulses. The Low battery trigger point can also be set earlier or later if you prefer. The default operational settings are: 50 pulses per minute (ppm), a 60 millisecond pulse width and approximatey 60 hours before the low battery mode begins.

    You can send the transmitter direct to Marshall Radio to custom reconfigure it or change the channel if needed. The first time is free, after that we charge a $25 fee is all. Same day turnaround guaranteed.

    What does your Warranty cover?

    Our three-year warranty is the most generous in the business. There is a 30-Day Satisfaction guarantee which means you can return it in like-new condition for any reason. After that, the Warrantee covers defects in both workmanship and materials and we will repair or replace it and return it to you free of charge. We work to be both generous and reasonable with Non-Warranty situations as well.

    One thing to remember is that using a non-Marshall replacement antenna will void the Warranty.

    Image Gallery

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    Three sizes of TrackPack Three sizes of TrackPack
    TrackPacked PowerMax TrackPacked PowerMax
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    PowerMax on a tiercel Cassini using TrackPack PowerMax on a tiercel Cassini using TrackPack
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    PowerMax on female peregrine using TrackPack PowerMax on female peregrine using TrackPack
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    The ideal set-up for longwings The ideal set-up for longwings
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    Bottom View Bottom View
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    Open with battery Open with battery
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    Still OK as a tail mount Still OK as a tail mount
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    The ideal backpack design The ideal backpack design
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    PowerMax antena change PowerMax antena change

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