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Feb 02, 2016, 11:59 PM
Rana
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.

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.

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.
The most powerful RC + Telemetry system on the market "ULRS 2000mW" (0 min 27 sec)

Can also use fixed voltage 9V, 2A LDO in TO-220 3pin package and keep it inside the casing of the OrangeRX 1W
module with heat shrink on the regulator to keep it isolated. Recomended parts are BA90DD0T (9V, 2A LDO),
L78S09CV (9V, 2A LDO).



Latest update:

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.
ULRS 2.5W power mod (0 min 20 sec)


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.

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.

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 maximum upto 10V, +/- 0.1V

While doing this mod, wear anti-static wrist band as MOSET's are susceptible of getting damaged due to static charge.

Update as on 19th Feb 2016:

I have traced the entire RFM23BP board and made a rough hand drawn schematic, and found few design limitations like the RF switch can handle 1500mW input power. I have found some other RF switch chips with same footprints but which can handle much higher input power.

A PNP transistor controlling the gate bias of the RF power MOSFET, is being derived by GPIO_1 pin #8 of RF23S directly without any resistor in the path.

I might consider designing my own but a better one than this.


Update as on 22nd Feb 2016:

The PNP transistor used for gate bias of RF power MOSFET is in SOT-323 (SC-70) package and have hfe (forward current gain) between 125 to 400 and the transistor has maximum collector current "Ic" of 100mA.

In present configuration this transistor can attain maximum collector current of 3.5mA due to two series resistors 503 ohm + 439ohm = 942ohm connected from collector to GND. GP I/O's RF23S chip on the RFM23BP module outputs VDD-0.6V on high level.

Considering minimum hfe of 100, theoretically the base resistor value is coming out at 77K ohm but there is no option on the PCB to incorporate this base resistor.

In one of my module where I given 3.6V externally to the chip RF23S, and run for long time, this PNP transistor was actually damaged by the chip's (RF23S) high I/O voltage and due to no base resistor.

I was surprised to see that there was no RF output, lateron by tracing and testing the transistor, I found it faulty which always tied the gate of the RF MOSFET to GND and not allowing to amplify anything.

For a new design, its must a minimum of 10k resistor and this PNP transistor be in slightly bigger package SOT-23.

Update on 20th June 2017:
There is update in the traced hand sketch schematic of the RFM23BP module. Collector of the PNP bias transistor (which switches on - off the RF power MOSFET), also goes to the base of RF driver NPN transistor with SMD marking "R25", via 1.5K ohm resistor and then an inductor (created on the PCB via copper track).

There is also a 100nF capacitor connected between the collector of the miniature PNP bias transistor and GND.

Now, with this information, I reaches the conclusion that this miniature PNP has and additional load of +ve biasing the RF driver transistor R25. Already there is no base resistor between the base of this miniature PNP biase transistor and the GP I/O 1 which makes it much prone to failure due to excessive base emitter current (also analysed by Ben).

This recent information puts stamp on the the fact that there is a design flaw in RFM23BP which increases the failure rate and that is a missing resistor between base of the miniature PNP bias transistor and GP I/O1.

Any regular TO-92 package BC556, BC557 transistors can be used to achieve the functionality of this miniature PNP bias transistor but this would require some small wiring.

With this new information, it has also become clear that RF driver transistor(s) are not operating in Class-C but just in Class-A only.

Due to time issue I am unable to devote much and came house today evening only and have to rush out tomorrow again. Once I again reaches back, I would possibly suggest optimum modification.

Update 21st June 2017:
I have added two images here and to my main old post. These give more details about the schematic on the PCB.
The other image shows how to use BC556 or BC557 TO-92 package transistor as an alternative to miniature PNP transistor which goes faulty due to design issue on not using resistor between GP I/O1 and base of this PNP transistor.

I have given general idea, its upto the user, where to place the through hole to-92 package transistor BC557 on the board but one thing must be kept in mind is to keep it away from RF power MOSFET and its output inductors in order to prevent parasitic value change of RF components and to avoid RF injection on the base of the transistor.


Update on 22nd June 2017:
The SMD marking on the RF power MOSFET on few of my boards, I observed long back was W 2 2 Z, see the image attached.
After looking at the datasheet posted by Ben.

it seems HopeRF guys did yet another design mistake, they forgot to put 39pf capacitor from gate of the RF power MOSFET to GND which is must as per the application schematic @450MHz. This is needed to match the complex input impedance of the RF Power MOSFET.

I have suggested a location to solder this missing 39pf cap but I am not sure, how much would it improve RF output power.
The fundamental reason of R25 getting hot in RFM23BP boards of most users is the 1.5K resistor via which the driver NPN transistor R25 gets +ve bias from the miniature PNP transistor.

50% of Vcc means 3.3V/2 = 1.65V is the +ve bias voltage the R25 transistor gets on its base when TX is on means miniature PNP transistor switches on. During TX on period, 2.1mA current flows through the base - emitter junction. Let us assume a practical hfe value of 250, that case collector current would like to go upto a value = input current X hfe = 525mA. Oh my God, that's hell lot of current ! which is making it hot.

With present bias resistor of 1.5K, we just can not make the +ve power supply of the driver transistor R25, common with RF MOSFET which can go upto 10V. We have to change this resistor to a higher value maybe 10K.

Update on 27th June 2017:
I have observed in two fresh RFM23BP modules that the SMD marking on the tiny bias PNP transistor is E13 and it's part number is DTA143ZKA and package is SOT-723 (measured with digital vernier caliper) .

It is surprising to see the datasheet that Tiny bias PNP transistor having SMD marking E13 has inbuilt two resistors, see the image attached below. This has turned around the observation about this transistor. The resistor is already present then why this transistor is getting damaged ?

For those who says we are happy with 800-1000mW RF output power of the ULRS, refer this mod image, its self explanatory.

1. Cut the track carefully with fine knife by viewed under enlightened lens.

2. Solder another R25 in parallel and use 4.7K series resistor which goes to collector of PNP bias transistor in place present 1.5K.

3. Solder 39pF and 100nF cap as per shown in the attached image.

4. Connect +5V, 2A regulated power at the pad towards RF power MOSFET before the track cut, refer attached image. Use external switching regulator for this.

Test it for more than 24Hrs, if no issue observed (observe temperature of both R25 transistors), its done !

By using 10K inplace of 4.7K and replacing +5V by +9V, you will get 1500-2000mW and 2000-2500mW with +10V
If you do not need more than 800-1000mW then don't go beyond +5V.
Last edited by narpat007; Jun 28, 2017 at 10:02 PM.
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Feb 03, 2016, 12:04 AM
Registered User
Sounds very interesting!!! Can you share the mosfet part number I want to check the datasheet to see if this approach meets the specs or not.
Quote:
Originally Posted by narpat007
ULRS @1627mW with OrangeRX 433MHz 1W module without any component change

Hi Ben !
I have a great news for and that is I have done something for which my name deserves to be in golden on the ULRS page.
Achieved 1627mW out put power with OrangeRX 433MHz 1W module without any component change.

Video clip is uploading at the moment, I will soon share detail. 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 1627mW RF output power.
Feb 03, 2016, 01:40 AM
Registered User
Thread OP
Hi Narpat,

I guess you deserve again the mad scientist badge
Feb 03, 2016, 02:30 AM
Rana
Quote:
Originally Posted by flipflap
Hi Narpat,

I guess you deserve again the mad scientist badge
Thanks a lot Ben !
Its more than 2 hours now, the RF power MOSFET is running excellent without any heat sink, Temperature is 150 deg F, only little warm, no hot at all.
Feb 03, 2016, 02:34 AM
Rana
Quote:
Originally Posted by samisin
Sounds very interesting!!! Can you share the mosfet part number I want to check the datasheet to see if this approach meets the specs or not.
Hi, I had written to the manufacturer of RFM23BP but they did not tell anything about the part number of the RF power MOSFET used in RFM23BP.

I guess its 12V rated maximum. I recommend not to exceed 10V . Most people will get around 2000mW at 10V.
This particular module of mine was giving around 150mW less power as compared with others at 5V (my old mod)
Last edited by narpat007; Feb 03, 2016 at 02:49 AM.
Feb 03, 2016, 03:20 AM
Registered User
I am wondering how stable is gonna be. I mean harmonics and longevity.If we find out the part number we can answer these questions
Quote:
Originally Posted by narpat007
Hi, I had written to the manufacturer of RFM23BP but they did not tell anything about the part number of the RF power MOSFET used in RFM23BP.

I guess its 12V rated maximum. I recommend not to exceed 10V . Most people will get around 2000mW at 10V.
This particular module of mine was giving around 150mW less power as compared with others at 5V (my old mod)
Feb 03, 2016, 05:12 AM
Registered User
ghostwhiper's Avatar
Quote:
Originally Posted by samisin
I mean harmonics and longevity.
Overdriving mosfet's or transistors do mess up the SWR a lot because of saturation.
i wont go so far, the standard module with a good antenna system at 5 volts has more then enough range then needed.
Feb 03, 2016, 05:49 AM
Arrière pays Niçois
salience's Avatar
Quote:
Originally Posted by flipflap
Well anything above 4.2V should be OK.

The more margin there is, the better. 5V is OK, but 5.5V or 6V or 30V are still better.

About powering the APM and the ULRS with the same supply there's no safety issue, but I've noticed that it affects the precision of the APM sensors (visible on the artificial horizon). That's because the ULRS pumps a lot of power in short pulses, which in turn affects the 5V line of the APM.
So that's just the RFM that requires short pulses of current? What kind of amps would that be?

Therefore if one powers the RFM with 5.5-6V from source A (for full power), one could power APM/Pix/ULRSboard from source B (the 5V power module or another BEC) and avoid the "precision problem"?

Perhaps a page on the website "powering the ULRS + FC" analogous to the "powering the PixHawk" page would be good. Could show the various options including the redundant PS configuration which I think is not a bad idea, could save you from a failure in power resulting from a BEC or PModule failure. Especially considering the cheapo quality of some of these PModules or voltage regulators.

EDIT: Maybe a (additional) capacitor added could smooth out the power when using PModule or VReg to supply everything? The VRegs I use have 2 small caps already...
http://www.ebay.com/itm/380755874794...e&talgo=origal
I like these for adjustment precision, the pot can dial in a quite precise voltage that doesnt seem to drift at all with input volts change. I did get a couple of defective ones, where the board seemed to be reversed, "input" marked "output" - smoked two like that until I figured it out!
Last edited by salience; Feb 03, 2016 at 05:57 AM.
Feb 03, 2016, 05:59 AM
Registered User
I just ordered a few more of these:
http://www.banggood.com/XT60-2-and-1...-p-915424.html

XT60 battery splitter. To allow me to run VTX or other equipment on the same battery as the the rest. The other solution would probably be to just solder JST connector the wherever there is full power.
Feb 03, 2016, 06:08 AM
Arrière pays Niçois
salience's Avatar
Quote:
Originally Posted by narpat007
ULRS @1858mW continuous power with OrangeRX 433MHz 1W module without any component change

Hi Ben !
I have a great news for and that is I have done something for which my name deserves to be in golden on the ULRS page.
Achieved 1850mW out put power with OrangeRX 433MHz 1W module without any component change.
Hmmm. I thought I noticed a sudden 433 pulse here yesterday morning - I thought it was some local HAM operator... All the way from India to France. Amazing;>)
Feb 03, 2016, 06:36 AM
Registered User
Thread OP

The Narpat 2W Project consequences : UK without internet


1 hour ago : the Narpat 2W project had unexpected consequences in UK

http://www.theinquirer.net/inquirer/...nesses-offline

Quote:
The firm has yet to confirm what caused the downtime, but told us that the company is confident that it was not a "malicious attack".
Feb 03, 2016, 06:46 AM
Registered User
Quote:
Originally Posted by flipflap
1 hour ago : the Narpat 2W project had unexpected consequences in UK

http://www.theinquirer.net/inquirer/...nesses-offline
maybe he caused a blackout with that 2W lrs
Feb 03, 2016, 06:57 AM
Registered User
Flipflaps

started any work on the Ultimate LRS extension : LCD Display
Feb 03, 2016, 08:42 AM
Registered User
2W of power... wow!... science is fun.
Feb 03, 2016, 09:09 AM
Registered User
ghostwhiper's Avatar
the best way to extend range is a good antenna.
the record for 446mhz with a PMR tranciever is set at 333 miles (535.8 km) with 500mw ERP.
https://en.m.wikipedia.org/wiki/PMR446

flying that distance would be near impossible because of the lack of fuel in a model
1 watt with a patch of yagi on the ground and a inverted V or dipool is capable of flying beyond the fuel capabilities


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