I recently dropped a line to the DIYDrones store folks when I noticed that images posted for the 915Mhz Air module in the store are different to the ones in the documentation and also picture shown of this module in the 3DR Telemetry kit.  I am mainly interested if there was an change in the design / version release of the hardware and would like to know what is shipping currently?  In other words is there an updated air module to correct some problem?  Below are the comparative images. You can clearly see the main board in one version is purple and the other is green.  What is clearly evident is the orientation of the HM-TRP module.  For the all green circuit board design (photo shown in the store for the 915 Air module on its own) the HM-TRP module connector is parallel to the main board edge connector (FTDI-style pinout).  In all the other photos of the Air module (included in the kit photo and manual)  the HM-TRP module is oriented 90 degrees to the FTDI-style pinout.  

I can make out v1.2 on the all green board.  But cannot see the version on the purple main board version with  HM-TRP module on top and at 90 degrees to the FTDI-style pinout.

I just want to understand why there appears to be two different versions of the 915MHz airmodule? Does anyone know? When I tried to get a sensible answer from the store contact they thought I was referring to the air and ground module.



Note the differences between the HM-TRP component orientations in the above two images of the same item (3DR Radio Telemetry 915MHz Air Module).

Has anyone recently received their 3DR radio kit and can confirm what version of the air module they have.  I have not picked up on any other forum discussion on this.  Somewhat of a mystery to be solved.


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My air module is like the picture at the top - purple breakout board, daughterboard is rotated 90 degrees and soldered on using a pin header.

My ground module has a similar orientation to the bottom picture - green breakout board, daughterboard in line with the breakout board.

I recalled a comment by someone (Jake?) that the original layout (top picture with purple board) was not optimal for RF leaving the board. Maybe this is a fix?

I could have dreamt all that though........

Hi Greg,

It's just a manufacturing process change - the performance of the two is the same the tests I've done. Sam would be able to give more details, but as I understand it the new layout makes better use of the machines that 3DR have invested in.

I've had both types for a while, and haven't found any behavioural or RF differences.

Cheers, Tridge

Hai Tridge,

can this 3DR telemetry kit replace my xbee pro 900 which i usually use with my Mikrokopter Hexa? Perfomance?


Hi Tridge,

Thanks for the confirmation. I have ordered the 915Mhz kit now and look forward to getting my ground station setup and telemetry to my quad.

I’m not sure about the range. If you read the setup information the default settings give you only 1 Km (that’s only 0.6 miles for us in the US). The Xbee says 6 miles. I am not a radio expert so I don’t know for sure if that really means that the Xbee really has 10 times more range?

@Mike & Meez

Andrew has a very comprehensive wiki on these radios in which contains your range answers. From what I have read, no less range than an XBee and a much bigger feature list.


ok ok i've already placed an order anyway. Will give it a try with MK.

Just another quick question.  Has anyone connected the 3DR Radio Telemetry air module to the APM1 board.  The wiki talks about connecting the APM2.   I am hoping this product is supported on both APM1 and APM2.  I don't see any issue since both have a similar telemetry port specs, but thought it better to ask just to be safe.

Hi Greg, the radios work on APM1 as well. They are not specific to APM2 or even telemetry, they can be used to TX/RX any standard TTL serial data, like you would with a pair of XBee Pro modules.

Greg, the green board is a revision of the first 'air' module, our shop is better suited for SMD assembly and the first boards were a bit time-consuming to make. Both versions of the air module work exactly the same way.


Sam I appreciate your feedback. Good to confirm these things. I received my 3DR Radio telemetry kits this morning so I have a fun weekend ahead getting them set up. Cheers

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