Homebrew LMR SDR TRX

Homebrew LMR SDR TRX Design

This project is a variant of this following design from UT3MK https://ut3mk.at.ua/ , the AVALA SDR from http://yu1lm.qrpradio.com and YE3CIF SDR TRX : ye3cif.com/lmr-sdr-transceiver-10-160-meter-band/. Basically the design is a variant of the SDR-1000

Since this project is now finalized you can find it on PCBWAY and Arif YE3CIF has compiled the overall files here (Many thanks ARIF for your desing and this wonderful TRX) : https://www.pcbway.com/project/shareproject/SDR_Transceiver_10_160_meter_band.html

The SMD variant of this transceiver from Yuri UT3MK with additional features. This TRX is using THD and the only SMD is the SI5351

https://www.pcbway.com/project/shareproject/SDR_TRX___Super_Puper__synthesizer_.html

https://www.pcbway.com/project/shareproject/SDR_TRX___Super_Puper__main_board_.html

The TRX is covering from 160 up to 10m band and the final design is a compilation and integration from various sources. This is a very international project from Indonesia , Ukraine and France.

Hereafter a SDR TRX design example from the UT3MK Forum.

SDR TRX Design from UT3MK forum

The modified one with about -10-17dBm (0.1-50mW) output and the Band filters BPF relays are triggered with a 74LS145N which is providing the capability for up to 9 bands external LPF for the external amplifier. I am using a 2N3904 for the 50mw transmit amplifier and a BS170 for the receive preamplifier. Since some guys got some issue with the I2C LCD (Spurious and spikes during receive) , i am using a standard LCD without I2C.In addition , we are using only one CLOCK from the Arduino Nano (CLK0).

This SDR transceiver is using only 5 integrated circuits and 5 transistors. The arduino Nano is used a a clock generator and controller. Some Designer are using the STM32

The other differences are regarding the IQ mux (74HC4051) , the AF amplifier and we are using also different circuit with hopefully better performances.

The CD4051 is used as a quadrature detector. This chip is widely use and bring great performance for the symmetry of both analog I and Q paths.

The design is allowing to use a 25Mhz or 27Mhz Cristal and this can be setup with the main Transceiver menu.

The remote push buttons to change the mode and so on are removed in the final design

The 30w amplifier is already done and the main board is already equipped with LPF switching capabilities for the amplifier.

To feed the final amplifier , i use a class A amplifier in order to provide about from 1 up to watts output power.

This new design is able to provide the oportunity to use the device with PowerSDR and ExpertSDR software. The VFO is controlled , from PowerSDR or from the front panel encoder.

with the final front panel

An audio file from a QSO with PA3GEG

https://drive.google.com/file/d/1l8_uWAo1qHF3YkrUUEFv2ESnOPERUudP/view?usp=sharing

A QSO with Callum M0MCX

Final Schematic and Design

You can download the schematic here : https://drive.google.com/file/d/1V3bzmcbPLV4xXfHAe0pxwMqRyku0o9NY/view?usp=sharing

I/Q design

On board receive BPF

Synthetizer and Control

Transceiver in details

This transceiver is covering from 1.8Mhz up to 30Mhz.

Basically the TRX control from POWERSDR is based on the SDR-1000 TRX with obviously some differences (A lot in fact) and the main one is we are not using the LPT port since everything is controlled by the CAT protocol (Kenwood TS2000) from the Arduino Nano only.

The transceiver is not a DDC/DUC with stand alone capabilities and it is a front-end using a soundcard for IQ detection. Bandwidth 48/96/192 depending on the sound-card. PowerSDR or ExpertSDR software are used to control the overall features.

The overall cost was:
55€ parts (Components and the PCB)
30€ Case and knobs
40€ 30w mosfet amplifier + Low pass Filter
80€ ASUS XONAR U7 MKII Sound card

Overall cost is about : 200 € , so needless to say this is cheap regarding the performance you can acheive and the pleasure to build and setup your own equipment .

The transceiver is the following set of functional units, combined on one board:
• This modified SDR transceiver based on the developments of Alexander US5NCJ, YE3CIF and UT3MK;
• synthesizer on Si5351 under Arduino control .The original arduino sketch is coming from UT3MK Forum and currently i am using the modified firmware you can download here : https://drive.google.com/file/d/1phx2hHXN3ZEg8itbpfaa1rRcNI_zXIEN/view?usp=sharing
• band-pass filters for 9 ranges, for low frequencies individual, for high frequencies combined; The filters are controlled with a 74LS145 with BCD-TO-DECIMAL inputs from the Arduino Nano
• controlled attenuator for attenuation of the received signal by – 20dB; in addition you can find a preamplifier capabilities with up to +10db amplification for the receive signal
• control unit for external low-pass filter for power amplifier.

As an indicator, a 16×02 LCD display is used, connected to the Arduino and you are able to monitor also the output power and SWR.

RF Power Amplifier is deliberately not in this projet, you can combine it with any RF Power. The output of this Exciter is about 10-50mW.

Currently i am driving a IRF530 Mosfet amplifier (10w) but i have just achieved the intégration of a class A + LPF amplifier. The integration is providing a great and perfect spectral purity . The Class A outpout power is about 5w watts which is perfect to drive my EL519 amplifier for a final output power from 80 up to 100 watts.

Below in this webpage, i put 2 amplifiers design base on 2n5109 and IRF530. i am still experimenting the 10w amplifier and currently it is very promising.

Synthesizer on Arduino + Si5351
This synthesizer is designed to work with an SDR transceiver in conjunction with modifed PowerSDR software initially used for the SDR-1000. The frequency of continuous overlap when using the original synthesizer microcircuit is from 1 MHz to 30 MHz, the upper limit depends on the quality of the Si5351 microcircuit used (may be less than 30 MHz). The Quality of your SI5351 will be the key (I need to test 3 different one before i found a good one) . Be sure also you are using a genuine 74AC74 and 74HC4051 (IQ MUX) otherwise you will have some issue for above 14mhz if you are using a 74HC74 (So it is obviously recommended to use the 74AC74)

The 74AC74 is divided by 4 the frequency provided by the SI5351 and this is more or less the same principle from the SDR-1000. So using a 74HC74 you likely won’t be able to go over 10 MHz because 74HC74 operates at frequencies up to 40 MHz. By contrast, the AC series supports frequencies up to 120 MHz (120 Mhz / 4 = 30 Mhz).

The frequency tuning step is set by the PowerSDR program, in the range from:
1Hz, 10Hz, 50Hz, 100Hz, 250Hz, 500Hz, 1kHz, 5kHz, 9kHz, 10kHz, 100kHz, 1mHz, 10mHz.
It should be noted that in the new versions of PowerSDR V2 (V2.5.3) there is a gross error in the assignment of a step after 1 kHz, and exchange via CAT stops when a step of more than 25 kHz is selected, which is not a malfunction of the synthesizer.

In addition , controlling the frequency generator on the Si5351, the Arduino module acts as a control unit for the entire transceiver, namely:

1. Switching band-pass filters.
2. Control of reception and transmission using the “PTT”.
3. Automatic activation of the attenuator.
4. Automatic inclusion of increased sensitivity of the transceiver with a preamplifier based on BS170 transistor.
5. Control of the transmission and reception modes of the transceiver and external PA – PTT
6. Indication on the LCD screen of the SWR value from an external SWR unit.
7. Measurement of output power at the level of direct wave. At 5V = 1.6kW
8. Controllable input for external microphone amplifier> compressor.
9. Indication of the received signal level (S-meter, points + dB)
10. Indication of the state of the communication port between the computer and the Led synthesizer.
11. Additional frequency control by means of an encoder.
12. Available correction of the generated frequency to units of Hertz.
13. On the additional port Si5351, a circuit of the standard signal generator is assembled.

Available in the transceiver

1. MultiRx mode (second radio).
2. Additional frequency control in MultiRx mode using an encoder.
3. Split mode with the ability to operate at split frequencies.
4. The step of adjustment by the encoder corresponds to the one set in the PowerSDR program

SSB, AM and FM modulation modes

1. Automatic suppression of unnecessary sideband.
2. In receive mode, the S-meter data is displayed.
3. In the transmission mode, it is possible to analyze data from the SWR meter.
4. The level of the forward wave of the SWR meter is used to calculate the output power and display its values on the LCD screen.
5. In the future, i am planning to add a current sensor to the circuit to measure the current of the output stage

The Synthetizer

The synthesizer-generated frequency is four times the frequency displayed on the PowerSDR.
The synthesizer provides a hardware frequency shift during reception and transmission – TX / RX. In transmit mode, the synthesizer generates a frequency four times that displayed on the program scale, and in receive mode, it adds a quadruple IF value (9000 Hz) to it. This is done for those who want to control it with a frequency meter.
All mathematical operations are assigned to the processor of the Arduino Atmega328 module. The processor operation algorithm is based on the semi-master principle, i.e. the synthesizer does nothing until it receives a command from the PowerSDR software. In this case, all installation commands are generated by the synthesizer itself when it is turned on.

Synthetizer features in details:
1. Frequency grid from 100 kHz to 55 MHz continuous overlap. ranges from 160m to 6 meters inclusive. Press + \ – to change ranges.
2. Frequency accuracy up to 0.01Hz with the ability to calibrate via MENU.
3. Using the + \ – buttons, the tuning step is from 1Hz – 20kHz.
4. To eliminate the step error above 25 kHz, the error is analyzed and eliminated by decreasing the step to 20 kHz.
5. Detuning works for both reception and transmission.
6. Full SPLIT mode. Including when the second radio is on – (MultiRX + Split) mode
7. S-meter 1 point up to + 60dB in 1dB steps.
8. The machine monitors and controls the ATT and Preamp modes.
9. Automatic switching of onboard range filters. In addition it provide additional ports for external control and low-pass filter of the power amplifier.
10. The TX / RX mode is performed both by the fixed mode button and via the jack for an external pedal (i am not using it)
11. With AM and FM modulation in transmission mode, there is a frequency shift.
12. Types of modulation can be changed directly with PoweSdr .
13. Only one Si5351 RF outputs is used
-CLK-0 Main operating frequency
-CLK-1 Is not used with this design
-CLK-2 Is not used with this design
14. Relay control of an external power amplifier is provided
15. There are two ports connected to the antenna bridge for analyzing forward and backward power. Calculations are displayed on the screen – SWR
16. Calculation and display of the output stage power taking into account corrections for SWR. The calculation of the power is carried out and according the SWR.
17. Software controlled attenuator -20dB.
18. The Menu provides:
a. Menu item for changing the frequency of the calibration beacon. Initially 4.996.000 MHz.
b. Entering the general error factor CorRef for Si5351 – this will allow you to adjust + \ – frequencies on CLK-0 (CLK-1 & CLK-2 are not used)
c. Menu item for selecting PLL values ​​from 600 MHz …. to 900 MHz
d. The choice of the used cristal from 25 to 27 MHz. 
e. Selecting the speed on the UART port 38400, 57600, 115200

Preamp and attenuator

The Arduino Nano has two outputs (A1 and A2) for Preamp and ATT features

(A1) and (A2) from the Arduino which is responsible for Preamp and ATT.

In the PowerSDR Preamp menu , when you select one of the modes, the ports on the arduino are turned on. This will enable the attenuator to be turned on as well as the Preamp (GAIN). There is also a state when they are simultaneously on or off. It can be seen from the table that with: 

OFF mode – the attenuator by -10 dB is on. As a result, attenuation by -10dB 

LOW mode – the attenuator by -10 dB is off and the preamp by +26 dB is off. As a result, 1 to 1. The low attenuation is my main one since is a neutral one. 

MED mode – the -10 dB attenuator is on and the +26 dB preamplifier is on. As a result, the gain is + 16dB 

HIGH mode – only the preamplifier of + 26 dB is on. As a result, the gain is + 26dB

The Attenuator is controled with K9 relay using a standard PI network :

The 26dB Preamplifier is simply using a BS170 transistor controlled by K3 Relay:

SWR and Power reading

On the LCD display you can have the output power and SWR reading. For this option you just need to build a SWR/POWER bridge and tap the output of the bridge to the dedicated plug on the main circuit

My initial choice was to use the SWR/POWER bridge from my main SWR METER (arduino build) for monitoring the overall data from my transmit line. I add a jack input at the rear of the casing and SWR / FWD voltage are coming from my Wifi SWR METER. Currently i am using this feature to monitor my Class A amplifier output.

Internal and external BPF/LPF Control

The synthesizer is designed to control the BPF/LPF for 9 ranges with switching on the relay. A low level signal (0, “ground”) is required to switch them. 

Please note the band dedicated Relay for BPF will be triggered according the frequency band you are choosing . During receive , the signal path will go thought all relay from the RX plug to the preamp relay K3 and K9 which is the relay for the attenuator.

Frequency stability

The frequency stability is determined by the stability of the cristal.
The output amplitude is highly dependent on the load resistance.
In idle state ~ 0.6 * times the supply voltage (3.3V).
Under load about ~ 2V For on head it is enough.
In the firmware, the average power value is set for its output.
This parameter further determines the amplitude swing of the output signal.

Connecting the transceiver board to the computer
Connect an electret microphone and headphones to the transceiver board. Connect shielded cables to the input and output of the sound card to the appropriate connectors.

The cable should be wrapped with EMI Ferrites and i am using this device for a good galvanic insulation.

For a PA, i can connect control signals to the power amplifier with POWERSDR and you can adjust the peak output power with the variable multi turn resistor located on the PCB. I am driving my Class A amplifier with only 10mw for about 5w output power.
The synthesizer is connected to a computer via a USB (mini / micro) cable (depending on the connector installed ). This is a standard adapter cable used to connect mobile phones or tablets to a computer. It is highly recommended to use a USB hub with the capability to switch off the USB voltage. You only need data . USB Voltage is creating a lot of spurious and spikes.

Computer data processing begins with the CH340 chip. It acts as a USB to RS232 data converter for further processing in the Arduino Nano V3.

Hereafter my CAT setting :

Connecting the 1602 LCD

Pay a special attention for the wiring of the 1602 display.

12 pins are used for the display. On the circuit board the pin 1 is the one at the bottom of the circuit board.

The PIN 1 up to PIN 6 from the circuit board –> PIN 1 up to PIN 6 on the 1602 LCD

PIN 7,8,9 and 10 on the 1602 LCD are not used

PIN 7 up to PIN 12 from the circuit board –> PIN 11 up to PIN 16 on the LCD

Arduino and SI5351

Arduino Nano V3 tweaks

The Arduino Nano is a nice tiny controller , therefore it can create some little spurious or spikes since the controller is not shielded

In order to ensure a proper purity from the controller , you can apply 3 tweaks:

-Remove the LED from the controller . Blinking LED can be very anoying and may provide a lot of spurious (Especially the RX and TX LEDs)

-Add some filtering capacitor to the 3.3vdc , VIN and 5vdc Arduino power supply pins. I am using a 1000uf capacitor to enhance the filtering.

-As mentioned , you do not need to supply any voltage from the USB since the ARDUINO is already supply with voltage from the main circuit. Computer may bring some spurious from the USB power supply.

All blinking LED were removed

With this tweaks , i manage to remove all the little spikes from the arduino and my Waterfall is really clean without any spurious. In addtion i notice the noise floor is about 2 to 3 dbm better.

As mentioned above, if you pay some attention with some galvanic insulation , using ferrites with your soundcard and USB cables , the TRX will be very clean and linear. It will assist also with the noise floor.

The transceiver linearity is really great with a very good and balance I and Q. The spectrum is free from any spikes or spurious.

The PCB

The PCB is a 2 Layers and size is about only 132.3 x 130.7 mm

Sound card

This kind of transceiver will need a sound card for I/Q management during TX and RX.

For a good quality signal and a signal to noise ratio , a good device is mandatory. Currently i have 2 SDR TRX and performed some test wirth the 3 following soundcards.

-Behringer U-PHONO UFO202

-Startech ICUSBAUDIO2D

-ASUS XONAR U7 MKII

The Behringer is not so bad but the signal to noise ratio is about -86dBm which is not so good during receive. The noise floor maybe an issue. This device is an entry level so do not expect much

The STARTECH , is 24bits with up to 96khz which is good in theory but in fact this soundcard is bringing some spikes during receive. The signal to noise level is about -95dBm . The transmit and receive quality is better compare with the Behringer

The ASUS XONAR is 24bits up to 192khz sampling. The signal to noise level is about -115dBm . Needless to say this device is a masterpiece for SDR TRX or if you plan to use it with TRX with I/Q output for a panadapter. The transmit and receive quality are cristal clear. In addition this device is providing more setup when using ASIO4ALL Drivers

The soundcard should be connected on the line IN and OUT of the transceiver

When i will have some spare time i will perform a video to show the differences between the device.

The ASUS XONAR is about 80 Euros but it will bring your SDR to another level really!

Final test and tuning

This is a video with the final tuning using the ASUS XONAR U7 MKII Soundcard

Final

The TX/RX Sequencer

i am using 2 relay for the RX and TX sequence , one is for the TX and RX and the other one is for the 2 watts Class A amplifier (power supply 12v)

Just below , the final casing . can be better but since i am not going to compete for a beauty constest with this TRX , it is not so bad

TX & Spectrum check

This check was performed with a TinySA, 20w output from my IRF530 Mosfet amplifier, RF coupler and a 1kw dummy load. The spectrum check was performed prior the Class A 2 wattts amplifier integration.

The following screenshot are demonstrating , the TX output is very clean.

CLASS A amplifier enhancement

The initial check from above measurements were satisfactory but not completely especially for 80 and 40m band, so i had decided to add a Tiny 2W Class A amplifier with associated BPF/LPF controlled by the 74LS145N.

Class-A Power Amplifiers are therefore typically used in applications
requiring low power, high linearity, high gain, broadband operation, or high-frequency
operation.

The absence of harmonics in the amplification process, allows Class-A to be used at
frequencies close to the maximum capability of the transistor.

Class A amplifiers are not the most efficiency for sure therefore in terms of spectral purity and IMD they are far better compare to class AB amplifier.

Since i need only 1 to 2 watts , a class A amplifier will be perfect and i do not need to scratch my head regarding the efficiency. The good thing is with such low power i can use this transmitter fanless.

The amplifier is followed with LPF to ensure a great spectral purity.

Few years ago i bought this tiny amplifier from ebay for my WSPR beacon and this amplifier was really working very well even during long WSPR transmission. This tiny amplifier is able to provide about 1.5w Class A with only few milliwats at the input.

https://www.ebay.fr/itm/174883128392?hash=item28b7d8c448:g:cqsAAOSw7JRhEfno

When i bought it few years ago itwas about 6 or 7 Euros only

Hereafter some figures regarding the amplifier performances.

The measurement was performed with a Nanovna

The following test procedure was used:
1. Turn the amplifiers on to allow them to warm up and guard against turn on transients damaging anything during testing.
2. Turn on the nanoVNA, set the display to CH1/LOGMAG only, 10 dB per DIV, reference position at 5 divisions to be able to see 20 dB gain.
3. Connect a 45 dB attenuator to CH1 and a 6 dB attenuator to CH0 to closely match the expected gain of the preamps under test which is about 20dB
4. Connect attenuators together using a cable. The nanoVNA should be showing a about 20 dB loss over the frequency range which is 80m up to 10m
5. Change to the calibrate menu and select “reset” and then perform a “through” calibration. The new reference should be 0 dB at 5 divisions.
6. Connect the output of the 6 dB attenuator to the input of the amplifier and output of the amplifier to the 45 dB attenuator.
7. Read the amplifier gain in dB directly on the nanoVNA using the marker display.

The SWR is almost perfect from 80m up to 10m with an average of 1.17:1

The amplifier gain is about 18.5dB with an average of 2w from 80m up to 10m

parameter	Min.	Type	Max.	Unit
Frequency	3.5	14	29	MHz
Pout CW	33	33	33.5	dBm
Power in		10		dBm
Gain	18	20	22	dB
Drain Current		1	1.2	Amps
Supply voltage	10	13.8	15	Volts DC
IMD3 2 tone		-34	-28	dBc
2nd harmonic		-30	-20	dBc
3rd harmonic		-30	-25	dBc

Obviously , a LPF filter is mandatory and hereafter the Figures after the LPF filter

Hereafter some figures regarding the amplifier performances after the LPF filter

parameter	Min.	Type	Max.	Unit
Frequency	3.5	14	29	MHz
Pout CW	31	32	32	dBm
Power in		10		dBm
Gain	18	20	22	dB
Drain Current		1	1.2	Amps
Supply voltage	10	13.8	15	Volts DC
IMD3 2 tone		-34	-28	dBc
2nd harmonic		-53	-50	dBc
3rd harmonic		-64	-60	dBc

On upper bands above 14Mhz , the 3rd harmonic is almost null

The integration is pretty much easy and in fact since this amplifier is Class A , it is powerered with 12vdc only during transmit. During receive the amplifier is standing by without any power supply. The very good surprise was according the heat and i do not need any cooling fan.

As mentioned above , the performances provided by this amplifier are really great . The modulation quality is really good and needless to say the spectral quality is compliant with the legal obligation we need to fulfill.

External LPF Control circuit

The LPF is triggered automaticaly by the dedicated LPF Control from the board and a darlington circuit using a UDN2981 or even better an ULN2804 because the logical level at the output of the 74LS145 are inverted. My initial design was using 8 NOT gate transistor design but with the ULN2804, it makes it far easier. The ULN2804 is able to sustain 12vdc up to 500ma .

More details and gerber files are here : https://easyeda.com/F5NPV

You can find some great LPF kit here : https://rv3yf.us/collections/bandpass-filters/products/universal-lowpass-filters-lpf . This LPF is able to handle about 100w

LPF with SWR/PWR and SEQUENCER

https://easyeda.com/F5NPV/ft8qrp-lpf_copy

The output power available after the LPF is about 1.3 up to 1.6w and the current is about 200 up to 300ma.The efficiency is about 50% which is not so bad for a class A amplifier

This LPF is also acting as a RX/TX sequencer and there is one output for the receive path.

Since a Class A amplifier are powered or biased in the “on” state , the amplifier during receive is not powered and the power supply (12volts) is applied only during the transmit.

Hereafter the measurement and results with this amplifier. The measurement were performed with my Mosfet IRF530 amplifier with a power of 30w output on a dummy load with a RF Sampler to feed my TinySa

80m

40m

20m

15m

10m

The results as expected with a Class A amplifier are really good and even exceeding my expectations.

IMD and the modulation envelope are really good also

FINAL INTEGRATION and SPECTRUM

Some pictures of the final integration with the 1w up to 1.5W Class A amplifier. In addition i have integrated a homebrew SWR/PWR bridge and the LPF filter for the Amplifier.

This configuration is providing me about 50w up to 60w with my single 6P45C tube amplifier

The LPF

The SWR/PWR bridge

The spectrum measument hereafter were performed with my 150w 6P45C tube amplifier with about 100w .

The Spectrum is almost perfect, therefore the fine tuning of the LPF was a bit tedious. The NANO VNA ande TINYSA were very precious tool in order to achieve such result.

SWR/PWR bridge

In order to supervise the integrated amplifier from the front panel , i have integrated a homebrew SWR/PWR bridge

SWR Bridge

For VD Diodes , i am using BAT41 diodes or 1N5711 . For R1 and R4 since i do not have 50R Resistor , i am using 47R 5w resistor . The Menu is offering to adjust the Resistor Value.

The Toroid core is a ft-80-43 or 140:43 with about 30 turns (The size of your toroid is according the power you are using)

The gerber file for the SWR bridge : https://drive.google.com/file/d/1i1FAbeb4EyGl6EbUAo1TmMHviFV_yVLi/view?usp=sharing

Alternative SWR bridge

The link to download the SWR Bridge Gerber file : https://drive.google.com/file/d/1OKnSJLDMavRQmTEpTh-a3gz-aksZtfnM/view?usp=sharing

The Following was with the IRF530 amplifier testing and SWR / PWR bridge calibration

1 to 3w Amplifier Alternative

This is another alternative for a tiny amplifier as a driver for your QRO amplifier.

The amplifier is about 16 dB. At the output of the amplifier, a 6dB Attenuator is part of the design but can be removed. Taking into account the attenutor, the output power of the amplifier is about +30 dBm (1 watt). Without the attenuator the output power is almost 2.5w but definitly not sure the transistor will sustain it. The operating frequency range of this amplifier reaches 500 MHz. The amplifier usually starts working immediately and does not need to be adjusted. The circuit is also stable when the supply voltage is unchanged. Alternatively you can use a 2N3866 which is almost equivalent . With a 2N3866 the output power is a bit higher with about 3 to 4w without the attenuator. The best is to use a transistor socket and you can swap the transistor with ease

My second TRX is equipped with this amplifier. You can remove the 6db attenuator a the output (My final amplifier need only less than 1w)

The gerber file :

gerber_2n5109Download

10w Amplifier (Ongoing testing)

This design is not finalized yet and i am still testing it. With 13.8vdc this amplifier is able to provide up to 10w . This tiny amplifier is using a 2N5109 as a driver and a IRF510 or IRF530 (i am still testing both mosfet) for the final. This amplifier should be followed with a LPF filter.

All details : https://easyeda.com/F5NPV/5w_rf_amplifier_irf510

With 50mw input from the SDR , i can have from 5w up to 10w output. this level can be adjusted with the variable Resistor (Driver).

The 2N5109 driver working range is from about 0.5 to more than 30 MHZ with 16 dB of stable gain and very good linearity. It can produce +15dBm up to +30dBm of output power, while still in linear operation.

The IRF530 biasing is about 3.7vdc and 20ma.

J1 : the main purpose is in case of current sensor integration or if you prefer to use a separate power supply with current limiting capabilities.

T2 Transformer: you can use a FT50 or FT37-43

For this transformer the wire should be twisted. During the winding you need to identify 2 pairs :

-Pair identify with 4 and 3 is the primary

-Pair identify with 1 and 2 the secondary

The link for 2 and 4 is on the PCB and you just need to solder the 4 identified pins on the PCB. This transformer is providing a 1:4 ratio

T2 Transformer

For T1 transformer it is pretty much the same principle and the main difference is regarding the number of turns which is 10.

Obviously the IRF530 should use a heatsink .

i will put the Gerber files when all tests will be done

FANLESS PC

For PowerSDR i am using an industrial FANLESS PC with a dualboot (Ubuntu + Windows 10). The computer is located underneath the table. I am using a wireless Mouse + Keyboard

BOM

Component Name	Designation	Qty	note
ARDUINO NANO V3	ARDUINO NANO V3	1
105	C1,C2,C15,C16,C17,C18	6	multilayer
221	C13,C14	2	ceramic
10uF	C19,C20	2	elco
223	C21,C22,C23,C24	4	ceramic
221	C25,C26	2	ceramic
100uF	C28,C30,C35,C77,C93,C94,C96	7	elco
10uF	C29	1	elco
104	C3,C4,C31,C36,C37,C38,C40,C39,C89,C90,C91,C92,C95,C97,C98, C99,C100,C41,C42,C43,C44,C45,C46,C72,C73,C74,C75,C76	28	ceramic
10uF	C33,C34	2	elco
102	C47,C48,C49,C50,C52,C53,C54,C55,C60	9	ceramic
10uF	C5,C6,C7,C8	4	elco
201	C51	1	ceramic
561	C56,C57,C59	3	ceramic
121	C58,C70	2	ceramic
471	C61,C65	2	ceramic
361	C62,C64	2	ceramic
391	C63,C66,C68	3	ceramic
181	C67	1	ceramic
271	C69,C71	2	ceramic
223	C9,C10,C11,C12	4	ceramic
1N4148	D1,D2,D3,D10,D9,D13,D14,D15,D16,D17	10
5V6	D11,D12	2	zener
TL084P	IC1	1
NE5532N	IC2	1
74HC4051	IC3 (Be carefull with fake one)	1
AMS1117 5.0V	IC4	1	smd
74AC74N	IC5 (Be carefull with fake one)	1
74LS145N	IC6	1
AMS1117 3V3	IC7	1	smd
7809	IC8	1
PINHD-1X3	JP1	1	DC IN
encoder dial	JP2	1
SWR	JP3	1	header
PTT IN	JP4	1	molex
to LPF	JP5	1	header
TX OUT	JP6	1	molex
RX IN	JP7	1	molex
LCD 16X2	JP8	1
Relay 12v	K1,K2,K3,K4,K5,K6,K7,K8,K10,K9	10	8 pin
100uH	L1,L2,L19	3
1uH	L10,L12,L14	3
0.47uH	L13,L15,L17	3
0.22uH	L16,L18	2
47uH	L3	1
4.7uH	L4,L6,L8	3
10uH	L5	1
2.2uH	L7,L9,L11	3
TX	LED1	1	RED
RX	LED2	1	GREEN
CAT	LED3	1	YELLOW
BS170 / 2N7000	Q1	1
27 / 25MHz	Q2	1
2N3904	Q3,Q4,Q5,Q6	4	npn
2N3906	Q7	1	pnp
2K2	R1,R2,R28	3
100	R13,R63	2
1K	R17,R18,R19,R20,R27,R32,R31,R43,R44,R49,R50,R51,R52,R53,R 54,R69,R41,R42,R61	19
68	R29,R30	2
10K	R3,R4,R5,R6,R7,R8,R15,R16,R21,R22,R23,R24,R26	13
220	R34	1
560	R35	1
6R8	R36	1
33	R37,R39	2
390	R40	1
15K	R45,R46,R58,R60	4
02/02/21	R47	1
10K trimpot	R48	1	multi turn
4K7	R55,R56,R57	3
150	R59,R70	2
470	R62	1
10	R64	1
100 trimpot	R65	1	multi turn
240	R66	1
62	R67,R68	2
330	R9,R10,R11,R12,R25,R33,R38	7
SET	S2	1	tach sw
Si5351A	U1 (Be carefull with fake one)	1
PHONE	X10	1	audio jack
LINE OUT	X11	1	audio jack
MIC	X8	1	audio jack
LINE IN	X9	1	audio jack
Pin Header	male + Female	1

All ICs (except the SN74AC74 and SI5351) , transistor ,resistor and capacitor are from MOUSER

The relays , the arduino nano, the inductance and many more are from Aliexpress:

Arduino Nano : https://fr.aliexpress.com/item/4000036402472.html?spm=a2g0s.9042311.0.0.7ec56c37Fsgs7j

The inductance : https://fr.aliexpress.com/item/4000709985793.html?spm=a2g0s.9042311.0.0.7ec56c37Fsgs7j

The SN74AC74 : https://fr.aliexpress.com/item/4000115726569.html?spm=a2g0s.9042311.0.0.27426c37fk9sRW

The SI5351 : https://fr.aliexpress.com/item/32906315061.html?spm=a2g0s.9042311.0.0.27426c37XhiEbn

The audio connectors : https://fr.aliexpress.com/item/32694891007.html?spm=a2g0s.9042311.0.0.27426c37Y4ECwk

The relays : https://fr.aliexpress.com/item/32656965533.html?spm=a2g0s.9042311.0.0.27426c37x8GXyn

Download

For the download because of WordPress restriction the files are with *.doc extension . Nevermind it is in fact a zip file and you can extract the file using your favorite winzip or any other archiver software.

Special release for PowerSDR you can use : https://drive.google.com/file/d/13RvNX7iPxzgHR3kxQk0YyhJ7pMIW5mMo/view?usp=sharing

Arduino Nano V6 hex file :

https://drive.google.com/file/d/1phx2hHXN3ZEg8itbpfaa1rRcNI_zXIEN/view?usp=sharing

Gerber Files:

https://drive.google.com/file/d/15bJM71A4pfZqxM-sm_Mbsj1eakzSLGMM/view?usp=sharing

BOM :

https://drive.google.com/file/d/1KkTR9BTD5XPy3ph2_YG5D54OhG7Ay-50/view?usp=sharing

Multiple PowerSDR release for homebrew SDR:

https://powersdr.mis.ks.ua/download.html

you need to download :

PowerSDR 2.8.0.187.1 X64 – Modified LPT driver 64bit

or

PowerSDR 2.8.0.187.1 X86 – Modified LPT driver 32bit

PowerSDR Setup

First you need to download the following PowerSDR software. This Software was initially compiled for the SDR-1000 TRX which was using the LPT port . For our TRX you do not need the LPT port (Must be setup to zero ”0″) and all is controlled by the CAT connected directly to the Arduino Nano.

http://cloud.mis.ks.ua/index.php/s/YQGJrcLMGT2WKrB

Then the setup is pretty much straight forward and you just need to to setup according the hereafter screenshots:

It is mandatory to setup the LPT address to 0 (zero)

LPT ADDRESS Should be setup to 0

Then you need to setup your CAT control

Soundcard setup using the Asus XONAR , you will to adjust this setting according the soundcard you are using.

When opening PowerSDR you will need to create your Transceiver setup

Add your transceiver TRX

Then just follow the following screenshots

CAT and VAC configuration

For virtual channels VAC i am using com0com

Transceiver Calibration

The SI5351 needs to be calibrated . Inorder to achieve this task you will use the dedicated menu provided by the arduino firmware and PowerSDR

You will need to tune your VFO for example on 10Mhz (DSB mode) and press the S2 to access the calibration Menu (CorRef)

The red vertical line should be in the middle of the 10Mhz reference signal peak.

If you are using a rotary encoder which include a swith you can wire S2 on it

The CorRef Menu : you just use the rotary encoder to change the Reference value. When done you just need to press the reset on the Arduino nano to save the value.

Hereafter a quick video to explain the calibration process which is very simple:

CW

For CW you can use this simple circuit

The following setup should be applied to PowerSDR and it will be according your COM where your adapter is detected by Windows . Mine is COM1

You will need to adjust the signal shapping according your preferences.

For automatic call you can use the CWX features

If you are Not comfortable with this circuit you can instead use a FTDI RS232 Adapter

This solution is working also very well. The PowerSDR settings are identical compare to the previous circuit.

Final and presentation

QSO using the SDR TRX

Summarize

First of all , i really need to thanks a lot :

-YE3CIF, Arif from Indonesia . A great designer and homebuilder. You can find now the PCBWAY project compiled by him : https://www.pcbway.com/project/shareproject/SDR_Transceiver_10_160_meter_band.html (36 USD only for 5 PCBs, so it is about 7.5 Euros only for one PCB)

-UT3MK Shadrin Yuri from Ukraine for all information provided and thanks to his wonderful forum (https://ut3mk.at.ua/) where i can find all the information i need and especially for the Arduino Firmware.

Building this kind of transceiver is providing the oportunity to put your hand into the SDR technology which is definitly great. The simplicity of this kind of design is simply astonishing regarding the results and performances provided. This kind of transceiver is not a DUC/DDC transceiver and basically mostly dedicated as a base station.

Since this TRX design is simple , the key is to use :

-A good sound card and i recommand the ASUS XONAR MKII which is a blast in terms of performance. The Startech ICUSBAUDIO2D is providing decent results

-Genuine component especially for the SI5351 , 74AC74 and the CD4051 : This is mandatory for this transceiver.

The only difficulty is the soldering of the SI5351 , for other components they are THD standard one.

You don’t need to be an expert in either to build or operate a SDR
• Most of the “Digital” is in the computer/sound card
• All of the ”DSP” is in the computer software/firmware
• With SDRs, low cost does not mean poor performance at all

Since this tiny transceiver is really performing well , it is now my station main transmitter and use it daily without any issue so far.