For almost a year now, the ImmersionRC Tramp HV has been our video transmitter of choice for use in miniquads. It has all the features you generally want—a pigtail for easy antenna placement, adjustable power levels and a great channel selection. I think its most important feature over VTXs of yesteryear is serial communication with the FC (generally called “smart audio”). This allows you to change your channel and VTX power through your OSD using your controller. No more fiddling with buttons, accidentally knocking fellow pilots out of the sky in the process. SmartAudio has become the hallmark of high-end VTXs. With the AKK X2P, that may be about to change—
AKK X2P Introduction
Chinese manufacturer AKK has a surprisingly robust lineup of quadcopter electronics—including flight controllers, FPV cameras, and of course 5.8GHz video receivers and transmitters. I was drawn to their site by the AKK X2P 5.8GHz video transmitter, which is a fully featured VTX:
- $18.99 from AKK’s website (international) or $22.99 shipped from Amazon Prime
- Supports all traditional FPV video bands including Race Band
- Pigtail SMA female connector
- Two other connector options available: board mount SMA and MMCX
- Adjustable power output from 25mW to 800mW
- 7–24V power input support
- SmartAudio support, allowing channel adjustment from OSD
If this transmitter is any good at all at this price level, it’s a total steal! I’m going to take an extensive look at it in this review.
I opted to replace my aging LaForge VTX that I had installed in the Katak TRP I recently built. The LaForge in this quad has been having some noise problems that has been bothering me lately, and I don’t like how its 5V power input requirement strains the regulators in my all-in-one Asgard FC/ESC/PDB/OSD. It’ll also be nice to get smart audio on another one of my quadcopters.
Installation of the AKK was a breeze. I simply needed to cut off the wiring harness I had formed for the LaForge VTX and solder splices to the connectors that came with the AKK VTX. To enable SmartAudio, the AKK needs to have a single wire connected to a UART TX pin. I opted for UART 3 on my Omnibus F4 FC. I rewired the power input to the AKK to come directly from my battery. If you have a 12V regulator on your PDB, it may be better to use that to add increased protection for your video transmitter. However, the Asgard does not have this feature and I wanted to test how resiliant the AKK was to transient voltage spikes.
The AKK X2P does not come with any shrink wrap protecting its PCB. Depending on how you mount it, this may or may not be a concern. Remember that carbon fiber is conductive so you should not touch any circuit boards directly to it. You can, however, use sticky foam mounting pads if you are careful. I opted to use some 15mm diameter clear heat shrink to protect the AKK X2P. I bought a whole spool of this from Amazon a couple of years ago and have been using it ever since. It is great for ESCs but is a little too small for the AKK X2P—but I was able to get it around the VTX with a little bit of stretching using pliers.
The antenna connector the AKK X2P is of the pigtail variety. This is great for fitting a great many types of frames, but it does use a variant that bolts to the frame using two small screws on either side of the connector. These screws are not provided with the VTX and some frames might not have holes for them. Luckily my Katak TRP has these holes. Keep in mind that once you screw an antenna on to the connector, the antenna itself will hold the connector in place. For this reason, I believe that using hot glue or adhesive putty would be a fine way to adhere the connector to a quadcopter frame if you are lacking the screw holes.
With the physical installation complete, all that was left is enabling SmartAudio in the Betaflight Configurator. This is simple, just set the Perpherals dropdown to “TBS SmartAudio” on the appropriate UART in the ports tab:
After rebooting your quadcopter, Smartaudio should now be available in the “Features” menu of Betaflight OSD.
AKK X2P Review
Having put a few packs through my AKK X2P, I am pleased with it. Video quality seems average, with no more or less noise than I have experienced with other popular VTXs. In 200mW mode, range is also comparable to other video transmitters.
SmartAudio works as promised—great! The AKK X2P makes no mention of pit mode in its advertisement—but you can enable it via the SmartAudio interface and it works great. This is accomplished by entering the Betaflight OSD SmartAudio configuration menu and setting the “OP MODEL” configuration setting to “RACE”. After doing this, whenever the VTX powers up, it will transmit at an extremely low power level until you do a “SET” command via Betaflight OSD. I measured the power output of the VTX in this mode and my RF power meter did not even pick it up (so, less than .01mW). My goggles would only receive from the quadcopter when I was in the same room as it. This is great—it’s how the feature is supposed to work. By the way—this is referred to as “debug mode” in the manual.
I also measured the power output of each of the 4 power modes available on the VTX: 25mW, 200mW, 500mW and 800mW. My power meter is not calibrated, but I have found that it is generally pretty “close” from comparisons among different VTXs over the course of my testing career. The AKK VTX seems to transmit a bit higher (10-20%) on every power setting except for 800mW, which registers between 600–700mW. For reference, my Tramp HV registers at 500mW when it is set to 600mW mode.
I like the “user interface” of the VTXs one-button controller. Short presses allow you to flip through channels. Pressing for ~3 seconds puts the VTX in band select mode, such that short presses flip through bands. Each band is represented by a letter (for example, Raceband is displayed as “r”) – this is much easier to decipher at the field than numbers. Holding the button for ~5 seconds puts the VTX into power select mode which lets you pick from one of the four aforementioned power settings. When the VTX is idling, it will display the channel, band and power setting in sequence.
To refer back to the previous section—installation was fairly conventional. I liked the form factor of the connector with the two bolt holes because my frame (Katak TRP) supports it—this may be annoying to those who do not have these holes though. I also wish that AKK shipped hardware to bolt the connector to the frame with the transmitter. There are workarounds if you don’t have the holes or the hardware, though. One such workaround was seen in our recent Floss 2 build guide:
As it is, you will need to rely on your frame kit for that or your box of spares. For those who are interested, another model called the AKK X2, which is nearly identical to the X2P but has hard-mounted connectors, is available.
AKK X2P or ImmersionRC Tramp HV?
Over the past year, I’ve had a chance to use video transmitters from most of the major brands, including those from ImmersionRC, Team BlackSheep, FPVNinjas, Lumenier, ReadymadeRC and FuriousFPV. Until now, the Tramp HV has been my favorite for the reasons mentioned in the introduction. The AKK X2P is the first VTX since the Tramp was released that makes me waiver on my commitment to team Immersion. Not because it is a particularly fantastic design or anything—let’s be honest, VTXs aren’t exactly sexy—but because it’s a functional VTX with every feature I personally want, for around $20. It even “beats” other transmitters out by offering a 800mW power mode.
That being said—there are still reasons you may want to spend the $40 for a Tramp HV. If your local race crowd uses the Tramp wands to assign VTX channels, the Tramp is probably a better pick for you than the AKK. Also—ImmersionRC is a household name with a track record for great engineering and good customer support. Until I have more experience with AKK products, it would be hard for me to put as much faith in them as I do in those from Immersion. Is that worth paying twice the price of an AKK X2P? It’s an honestly hard question for me. For beginners or pilots looking to save some money, though, the X2P really is a no brainer.