The most powerful RC + Telemetry system on the market "Ultimate LRS 2000mW, 433MHz"

I have a great news for the RC community that you can DIY the most powerful RC + Telemetry system on the market "ULRS 2000mW" using OrangeRX 433MHz 1W module and my 2W power mode. You need to have a magnifying lens and a small tip knife to do this mod. My greatest gratitude to FlipFlap (Ben) for his excellent firmware of ULRS.

Gain of the power MOSFET may differ slightly from module to module so one can get variation of 100 to 150mW higher or lower. Did the 2W mod in OrangeRX 433MHz 1W module and got 2030mW at 9V Drain supply.

I have cut a track on the RFM23BP which connects the RF MOSFET to the 3.3V main power line and power the RF MOSFET with external variable power supply and set it at 9V, achieved 2030mW RF output power. 

After running throught the night, measured the temperature of the RF power MOSFET, is was 148 deg F, on touching it was just warm, not hot. Its because of the fact that the PCB design of the RFM23BP and its integration in the OrangeRX host board all together makes a large heat sink for the RF power MOSFET.

Tested with inbuilt spectrum analyzer of ULSRcc, did not observe any unexpected surprise. Perhaps you can analyze that better with your real spectrum analyzer.

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Comment by Dusan on February 6, 2016 at 10:40pm

My idea was one on the plane, other on the ground

Comment by Rana on February 6, 2016 at 11:03pm

Then how will you receive with same antenna ? As all telemetry radios does the switching from Trans to Receive mode automatically inside only.

Comment by Cool Dude on February 7, 2016 at 11:14pm

Excellent mod. Too bad that this frequency is not legal in USA. :-(

Comment by Ravi on February 8, 2016 at 7:33am

Narpat, You are an RF engineering genius. no one can beat you in this part of the world in this field. I remember how you were able to obtain ppm sum out from an ordinary futaba receiver.

Comment by Rana on February 8, 2016 at 9:54am

Thanks Cool Dude !, Hi Ravi, thanks dear !

In the desire of getting more with the present H/W of OrangeRX 1W 433MHz, I did bit more deep dive in the RF part and achieved 2.5W output power.

I realized that there is a small 3.3V LDO regulator chip in SOT-23 package on the RFM23BP module inside the OrangeRX 1W 433MHz module and there is another powerful 3.3V switching regulator module TSR-2433 available on the host board.

 

While looking at the datasheets of various SOT23 package 3.3V LDO's I observed that for proper performance of the LDO, the input voltage should be atleast regulated voltage of the LDO for which its is rated + dropout voltage.

 

In this case I measured voltage output of the LDO and it was 3.15V, means the LDO was underperforming. To verify this fact, I just removed this LDO and soldered a small wire link between the input and output solder pads of the LDO.

 

Then I measured RF output at same 9V of the drain supply as per my previous mod of 2W, I was getting 2319mW instead of previous 2030mW.

 

Then the increased the drain voltage of the RF power MOSFET, from 9V to 10V and got 2534mW. Kept it running throught the night and it was working perfect and the temperature was almost as previous.

 

So I would call it the ULRS 2.5W power mod.

 

 

Comment by Jose Alberto Soler on February 8, 2016 at 12:31pm

Is the software in any way based on OpenLRS or is it a completely new firmware?

Also, what is the bitrate and do you think it would be possible to add a video stream? I only need video in a 3-4 km radius

Comment by Rana on February 8, 2016 at 12:45pm

After the 2.5W power mode of the ULRS, in which 3.3V LDO is removed from RFM23BP, there were two SMD capacitors connected in the output of the LDO, which are no longer required there as on the 3.3V main supply entry point on the RFM23BP, there are two capacitors and LDO has alredy been bypassed (removed).

 

So I recommend one of the bigger SMD capacitor to be removed and soldered at the RF power MOSFET drain voltage Vd entry point and GND. Modified self explanatory image file is attached below.

 

I am also sharing pic of my IBCrazy style 433MHz open dipole antenna, I found its performance slightly better as compared with the original but that may be because I tuned it as per my requirement. This has slightly longer 50 ohm impedance rigid RF cable length and an additional option to mount on Skywalker or similar plane at suitable required location on the airframe.

 

 

Comment by Rana on February 8, 2016 at 1:00pm

Most of the RF Power MOSFET's of different manufacturers of same package (PW-X) used in RFM23BP, are rated 10-12V and have maximum of 4Watt output.  So it is not recommended to give more than 10V to the RF power MOSFET.

 

Since I have many modules so I could take chance of putting one module in risk by increasing the voltage upto 10.5V at which I got 2768mW.

 

Finally the RF power MOSFET got burnt at 10.8V, and running for one hour. So even 10.5V is not recommended, the safer side is 10V, +/- 0.1V

Comment by Rana on February 8, 2016 at 1:25pm

@Jose, you can use any firmware you want but with ULRS firmware you get RC + Bi-directional Telemetry. For video downlink, you need to use a video transmitter. 

For detail, you my have a look at my post @RCGroups

Comment by Ravi on February 8, 2016 at 8:52pm

narpat, I will call you now onwards an RF magician, (RF jadoogar!)

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