Digging into 3dr radio power

hello all .I have read the wikis and operated mission planer on apm 2.6 copter but am falling into the love of the 3dr telemetry thing I ordered and operated it 100mw module but am curious and even my search got me more not understanding the topic?! the tx power on air and ground …in the mission planner the max power is 20db how come we see 1w 433 3dr modules on market I mean if the mission planner supports only 20bm which is 100mw where are the other 20db in the 1w=30db power go… please reply in details I already read the documentation earlier ten times with no answer obtained !! and please how to operate for example a 1w telemetry module to get max power out of it from some one who operated it with experience.

thanks in advance

There are no 1W 433 3DR modules. Just shitty chinese clones with power amplifiers added to the output stage. They spitting out noise like hell, causing many problems on board. The only good advise it to avoid them.
If you need long range, then use radio module from RFDesign, at 868 or 900Mhz depending on your location.


I have set of 500mw 900Mhz radios that had a problem with spurious emission and one of them was drawing a full amp. Replaced the FET and capacitor on the final and got them cleaned up. But they are not very good quality modems. The power output is not actually adjustable on them.

The CUAV P9’s also make good long range radios, but they are not cheap. And they will not power from the USB port on your tablet or laptop, nor from the Power Module on the controller. The air unit comes with its own BEC to power it. They have a separate power port to plug in a separate battery pack for the ground unit. They have an optional WTR24 WiFi module that puts the ground unit on a WiFi network so you can connect multiple ground stations with UDP as well. We used these radios on our government contract helicopters with the WTR24, 20 statute miles is not a problem with them in the mountains.

The only issue with the P9’s is that they are not compatible with Mission Planner, nor do they run Simon-K firmware. They use a proprietary modulation scheme and can only be programmed with a serial terminal with AT commands.

thanks for reply Andras yes your right they are Chinese telemetry modules. in my location its legal to go 1w 915 and maybe more in case of hopping system. but iwant to understand if the parameter tx power limited to 20db in mission planner avoid the full power in case of Chinese modules say? and does the mission planner system scale it…?

thanks Chris , as I asked Andras I want to understand the power settings of mission planner and how do they affect higher power modules? and am interested to know from 3dr users what is the maximum some one can get out of say 100mw 3dr with dipole on air unit and 4 element yagi on ground? I saw one a you tube video where a Russian guy went out 100km with 100mw 3dr!!!and patch on ground

Yes, power in radio range is not the answer. The antenna is. I regularly communicate with other radio operators around the world on ham radio using less than 2 watts because I have huge 11 meter tall phased antenna array that develops a large amount of gain in the forward lobe of the antenna’s radiation pattern, with high f/b rejection.

Doubling the power only increases the gain by 3dB. 6-9dB gain in the antenna is walk in the park for 440 band or 33cm band antennas to get ERP.

Mission Planner will not work to set power for your radios. I have not seen any of those that are adjustable. And most of them have such terrible spurious emission that it causes problems with the rest of your electronics on the aircraft. The best thing to do with those is sell them to somebody that doesn’t know the difference and buy decent radios.

yes Chris but don’t forget telemetry uses 915mhz while I think your ham is in low MHz or even khz range …I want to know form people who really tested it what the maximum to pour out of the 100mw 3rd and how to get there

this power setting is for what and affects what and how does it affect higher power telemetry modules???

This was explained already but I’ll give it a go. The standard SiK radios have a Si4432 radio module that is configurable for output power as per your posted image. Radios with more power (500mw is common) have a fixed gain amplifier as an output stage. This amplifier is fixed so it cannot be configured via software. So if you set the radio for 20dBm it will produce 100mw X the Gain of the fixed amplifier. 10X presumably for the units you have if you believe what they state (I don’t).

I have a pair of the 500mw units and they are junk as I suppose are the units you have.

Junk is not a severe enough term. The ones I have, even after I fixed them, make the servos jump all over the place on a helicopter. The only way they would be usable is to tow the radio on a long-line, using the wires to tow it, and maybe it would be far enough away from the aircraft to not wreak havoc.

Ha, ha joke of the day :grinning: Maybe Andras description as “Shitty” is best…

Indeed, as Dave said the 3dr radio cloness from china claiming 500mW or 1W are simply put a PA at the output stage of a standard Si4432 module (or even worse a HM-TRP module).
Beside the noise they spit out, they will never work perfectly because the firmware needs to be modified to handle the PA stage in the output, and of course they did not modified it.

You can rather go with a 100mW version and some good antennas. A well tuned rubber ducky antenna pair can go for 2-4Km at least, and a patch or yagi directional antenna can go well over 10Km. (But you will need antenna tracker for them.)

However there is one issue with the standard SiK radios, the input stage of the SiK4432 is deaf just like my Grandma… If you really want long range with small power you need a LNA stage at the input. So we are back at RfDesign radios…

hello Andras thanks for reply am not so used to the Sik4432 module what do you mean LNA stage at the input

LNA means Low Noise Amplifier, it is used to amplify the received signal without increasing the signal to noise ratio significantly.

yes I got it, but I think its already implemented in the 3dr module that uses sik

if you have any proposals or had come across such diy thing for adding such an amplifier to a 3dr module ( I mean modifying it) and given that this idea works I request you send me the link or address please Andras

Nope, there is no external LNA in normal SIK modules.
And modifying one to add an LNA is not a straightforward task, I would say it is easier to build a new radio than try to hack an existing one. Sorry.

thanks for advice , there should be out there a board to send gps position at least to an antena tracker to follow for video, I need such a solution