Hi again! Today I have something that I have been waiting for quite long to review and it would be this ExpertRC RF Power Meter. This is an Russian opensource rf power meter, created by Redsonic from the expertrc.com The device is based on and AD8319 and Arduino Pro Mini and this is a cheaper (~50$) alternative to the Immersion Power Meter. This device can be bought straight from Redsonic’s ebay shop and I will leave a link to it in the description.
Because its made in fairly small batches it might be a good idea to send him a message and get some info on when it will be available again. This is cheaper than the Immersion Power Meter, but it has few more functions than it! It has 3 buttons for navigation through the settings, can be powered either from a micro USB port, that can be also used for example to update the firmware, or from a 5-16V in, that is also protected against reverse polarization. The device comes calibrated, but if we have some professional equipment it can be recalibrated when connected to our PC. It comes in such a convenient box and in the set we have a coax extension cable, 30db attuneator and two SMA adapters. I did already prepare my device by connecting it to my 5.8 gHz 25mW VTX and if we now would simply power on our device, it will start in power meter mode. By clicking the middle button we can set it up.
The first thing is the frequency of our TX. We can choose from 27, 144, 433, 868, 915, 1200, 2400 and 5800mHz. So basically all frequencies that might be interesting for us. Next menu is the measuring mode: CM=Constant Measurement.
The device constantly recalculates the output power and sends this data 3 times per second to the screen. This measuring mode should be used to check for example our 1.2, or 5.8 gHz video transmitters. Next mode is AM=Average Measurement.
Device takes 10 samples and sends it to the screen 3 times per second. MM – Maximum Measurement.
Maximum value for 1000 samples, for those TX’es that are sending its data, not constantly, but in bundles/packs. Next menu is the attenuator setup. To measure values up to 900-1000mW, we need to use an attuneator, for example the 30db, that we receive with the device. The last thing is the unit setup. We can choose if we want the device to show db or mW values. In the end of this clip you can find a video comparison between this device and Immersion power meter if you would be interested. We can continue to the second feature of this device, that is antenna tuning. For me this mode is more of a interesting perk, than a full feature, because it has some limitations. We wont be able to choose an exact frequency of lets say 435, 1260 or 5985mhz, and can tune our antenna only on the main frequencies. For sure this is an alternative method to making our antennas, using a calculator. You can decide yourself if its better or worse. I wont be able to show you how to tune the antenna, because I’m in a 3x3m basement, in optimal scenario, we should be in open space, with the TX far from us and with other rf devices that will send junk to our device magical electronics turned off, so they would not change our readings. In theory, when we will cut our antenna, piece by piece, the values on our screen should be getting bigger, up to the point of when the antenna is perfectly tuned for our frequency. If we cut too much, the values will start getting smaller again and we should make a new one 🙂 You can see how the values change if I move my VTX and move it near the device, if the vtx is closer, we can see that the values are bigger and if I move it back, they descend. It would work similar, when cutting our antenna.
Like said earlier – for me this is just a demonstration perk. The last two modes, are the same stuff that we would get with the Immersion Power Meter, but like I have said earlier, this device has two more perks. First one from them is the “Finder Mode”. If we will connect a directional antenna for our frequency, we can make our device work as a geiger counter. The closer we are to our VTX, and the better direction our antenna has, the faster our device will beep. My VTX is somewhere over there and if we will power on with the UP button pressed, you can see how this works. I think that this mode, can get really handy at some point of our FPV experience. This device is small, can be powered from almost anything, we always have the antennas with us anyway, so its kind of no brainier for me to toss it in my pocket when preparing for a flying session. The last function is the full screen mode, that we can choose by holding middle button when powering on. In this mode we can see how the frames sent by our TX’s look like. This is my 5.8gHz and this is the Flysky 2.4 gHz. I didn’t find any use of this mode yet, but its definitely nice to have it. For me this device is flat our AMAZING and
I really would like to thank Redsonic for his work and time spent on developing this. If you would like the comparison between Immersion Power Meter and this device, you can check it HERE. As always let me know what You think about it and SUBSCRIBE!!!