Before connecting the KitsAndParts. To do testing, I wanted to use the same type of Arduino that will be added to the Ubitx.
Si5351 HF Antenna Analyzer
Since the Ubitx already has a touch screen installed and the updated firmware, once testing is finished this upgrade should be relatively simple.
The testing board for the SWR Bridge will serve a dual purpose. Once testing is complete, this board will be used in another project. I wanted to have plenty of power available, so two LM are used to provide power regulation. The first LM drops the voltage to 9 volts and the second takes it down to 5 volts. This helps the power regulators stay cool and will allow operation without a fan.
Both regulators have a good heat sink installed. Connection of the SWR Bridge is the similar to what is suggested on several blogs and the Ubitx website.
The Ubitx website lists 0. I did not have any 0. The resistors and capacitors are supposed to drain accumulated charge when no RF is present. A sketch for testing has not been written yet. For basic testing the readings will be read through the Serial Monitor. A LCD screen may be added to make testing easier. Testing will be done with the Yaesu FT with low power and the Ubitx. The second SWR bridge with surface mount capacitors will also be tested. You are commenting using your WordPress.
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It only takes a minute to sign up. The final goal is to make it feature rich but right now im having trouble calculating the forward and reverse voltage from the ADC inputs or even from the raw voltages measured with my oscilloscope. From what I've read in similar projects this is usually a simple linear relationship between ADC input and the forward and reverse voltages, from there its just a matter of calculating the power as if the voltage were across a 50 ohm resistor. My conclusion is that the issue is most likely in my electrical design somewhere.
I only made a single Directional Coupler but tried a few variations for the envelope detection circuit. All variants of my circuit seem to have the same problem so right now my suspicion is an issue in my Directional Coupler.
But I've seen other people using the same design as me successfully, so it is just a guess. I could really use some help on what I might be doing wrong. So let me add some technical details. These are the details I'm testing against or want to achieve.
Below is the schematic for my design, the image also includes the various voltages DC read under various conditions. These voltages seem odd to me as I get a lot of reflected voltage even when the load is a 50 ohm dummy.
Each of the transformers in the schematic are winding rations. The "1 loop" winding doesnt make a loop at all but simply passes through the middle of the core. For some additional information here are pictures of the circuits. The first picture is the Arduino with a proto-shield containing the envelope detector the AD at the top is currently not used in the software and is high-impedance, so it can be ignored. The second picture is the high-power Directional Coupler. Everything was made by me obviously.
Here are my thoughts so far on possible causes, but most of them I havent confirmed or am not really certain they are the root of the issue rather than just considerations. The diode is in its non-linear region. I ruled this out because the issue persists at high power and doesnt explain the high reflected voltage. The issue is normal and I need to just calibrate for it in software.
Though I've been unable to figure out how. The hot glue I used that fills the center of the coils is lowering the Q of the coils significantly. This however, I don't think, would result in these symptoms. The two coils are coupling causing the high reflected voltage. However this didnt seem to be as big an issue in other people's circuits. I ruled this out because the issue persists at high power and doesn't explain the high reflected voltage.
Your measurement at 5W looks like it suffers from diode non-linearity. At higher power, the SWR is consistent but should be very near zero so it looks like diode non-linearity is not an issue for these higher-power readings.
Have built more than a few, and all have satisfyingly-low SWR with no calibration.QRZ Forums. Tags: ad arudino dds. I just finished my very first Arduino Sketch to control one of the cheap Chinese AD modules which are still available. I'm sure this has been done more then a few times, but it was a good practical learning project. The controller can also be used as a signal generator or transmitter VFO.
It has the to 10 meter ham bands pre-programmed, can be rotary encoder tuned in 10 kHz, 1 KHz, Hz or 10 Hz steps. I coupled a resistor SWR bridge with a sensitive detector with LED output directly to the square wave output of the module to use as a QRM free means of adjusting my manual antenna tuner.
KD1JVNov 19, VK4HAT likes this. Nice project, thanks for sharing. That looks like an intersting project. I've built a few generators with both PIC and Arduino. It seems that the bridge part would work with any low-power signal source, such as my HP signal generator, so that could be a project all by itself. I am curious why you are using the square wave output rather than sign wave.
Clearly, if someone were to use the project as a VFO, sign wave would be best. Is there something about the bridge that works best with a square wave input? I've also thought that if you were to bring the voltage going to the LED to an analog input on the Arduino, that stepping the frequency across a frequency range and measuring the voltage at that analog pin would allow you to automatically characterize the load - be it antenna, amplifier input, or another load that wants to be 50 ohms at a specific frequency.
I can see how useful the project is at tuning a tuner for a specific frequency, but being able to tell the lowest swr point for an existing dipole, for example, would be a great aid in pruning or extending as the case may be. It seems like there is a lot of room for revision and extension if you want. I'm looking forward to future releases. W1GCINov 20, Well, you cna do a little more than that with an arduino and ad KD1JVNov 20, I discovered a few errors in the schematic I first posted on my web site.
That is now corrected and I added some pictures of the completed project. KD1JVDec 2, Congratulations, I will build a similar project. The output impedance of your AD module is Ohm and the input impedance of your bridge is 50 Ohm. Did you place a transformer for the impedance mismatch? I'm using the square wave output which has a low impedance output and works just fine driving a 50 ohm load without any matching. A resistive bridge like this is best driven by a low impedance source. KD1JVDec 3, You must log in or sign up to reply here.
Show Ignored Content. Share This Page. Your name or email address: Password: Forgot your password? Register for a free QRZ account.Flavio SWR is the only measurement yet. If it does, RF-Power will also be displayed. Are you sure the diagram is correct? Which one is correct? I also noticed that, I think it should be connected to the second Arduino. I've done the mods but when I transmit, the power meter Nextion shows full scale deflection with nothing hooked up yet.
When I connect the two A4-A5 wires to the radio's Arduino nothing changes. Prior to that, I followed the standalone Signal analizer instructions and the A5 and A4 lines should be wired to the ubitx's Arduino A5-A4 ports as well.
When I first fired up the ubitx with the new addition S-meter only I forgot to connect A4 and A5 but everything worked without them. What are they for in the first place? Am I doing something wrong? Can't make it work. I was wondering if we all are using the wrong version.
In the video I see you're using ver 1. You said above ''The voltage from the sensor is recommended to be less than 3 volts'' How come A4 is sending continuos 5V to the I2C?
I may have damaged the A4 on the I2C meter by now.
Arduino based simple SWR and Power meter
Thanks for your continued efforts on the firmware! Band scan etc works fine. Latest github versions for the 2nd and raduino.
See my website mw0uzo co uk for pictures of the rig. Would be great to get this working! Hi Ian. Thanks for the VSWR firmware.
Working well, now waiting for some updates to this. Hi Ian I will be studying this. I'm a little behind as I purchased an Icom and have been working with it. I'm back here because Ashhar Farhan has his own antenna analyzer using a Nano, bridge, other circuitryvery compact said it was the only one that would fit INSIDE of his cube satand ever increasingly interesting software.
Tracking Gen, Spectrum analyzer of sorts, ect. Signal measurement capability, a sensitive signal measurement functionand much more. I"d need to check what you are doing with the one in here, and the EU1KY AA antenna analyzer you work with to see if either have done these things. If you are interested in what he is doing with his "antuino" here is a link, to a few videos.
Post a Comment. April 13, The voltage from the sensor is recommended to be less than 3 volts.Not a member? You should Sign Up. Already have an account?
Log In. To make the experience fit your profile, pick a username and tell us what interests you. We found and based on your interests. Choose more interests. The main reason for this project is to find the resonant frequency of loop antennas I'm intending to build for the 20m HAM band.How To Build An SWR / Relative Power Bridge - Part 1
This work is greatly inspired by the work of K6BEZ on a low cost antenna analyzer, a link to his slides can be found in the links section. The uC will set the frequency of the Si via the i2c bus, and measure the voltage of both the waves on two separate analog inputs, via the swr bridge. Wiring the ESP32 or the Arduino nano to the Si requires 4 wires; power and gnd, and the i2c data and clock lines:.
The difference is that the ESP32 will have the logic to do the frequency sweep and will generate the SWV freq plot, and in the Arduino case a PC side python script will send commands to the arduino to change the frequency and plot the resulting swr measurements. The Si library used is the Etherkit one, since it is much easier to use than the Adafruit one.
The github repo will also contain some sketches to test the hardware, for example an i2c bus scanner to search for the Si address and a minimal sketch to just set a frequency on the clock outputs. A link to the article is given in the links section. In my case the input pins of the arduino have a high enough impedance and the signal should be significant enough to get at least some reading, so in this stage I'm omitting the op amp for simplicity. I know it will give horrible performance on such a board, but i just wanted to see if the concept works.
Looks promising! Next i have to find an antenna or so with a known resonance frequency, and test if this little contraption can find the sweet spot. The wiring is shown in above photo, which is really straightforward. No passives required anywhere. Next up is the resistive SWR bridge, and the necessary adjustments to the main sketch to push the resulting swr value over serial to the python script.
Over the last month all components arrived, notably an ESP32, arduino nano and of course the Si The tests using the arduino are fine. This might be because the ESP32 is 3v3 and the Arduino 5v, but I don't have any means to test this hypothesis.
For now I'll focus on the arduino, next step is to write some Python to control the clock frequency using the PC, and create a repo on github to keep all the code and test scripts. After that the SWR bridge, which will probably the largest work block for me. View all 3 project logs. Create an account to leave a comment. I have tried all sorts of sketches for the ESP32 and Si like Cal routines but all do the same thing.
Are you sure? It might be that the 3v3 from the ESP32 is not enough, but I did not test further. The arduino worked for me, so I stuck with that.
I am just beginning to think through an automatic tuning system for a loop antenna. I only recently finished the loop antenna design and prototype. I need to work out a motor for tuning. I have been debating between a programmable clock square wave and a modified sine wave generator. I am not concerned about "losing power in the harmonics". I am thinking of placing the signal generator and detector at the antenna.
Instead of trying to compare forward with reflected power, I was going to excite the coupling loop with the signal generator and sense the resonant frequency with a sampling hairpin link near the tuning capacitor.In this post, we will be doing basic testing of the KitsAndParts.
The Arduino Nano put together in our last post will be used for testing. A basic program was written to read the forward and reverse voltages with analog pins 2 and 3. To make testing easier, an LCD screen was added to the test setup.
The library for the LCD has been used in multiple projects and works well. A link has been placed in the Arduino sketch for the website to download the library. The Sketch is very basic. The Arduino will read the values on the Forward and Reverse pins and display the calculated voltage on the LCD screen. Testing was first done with the Yaesu FT at 5 W to verify operation. To make it easier to document for this post, the Ubitx V5 was connected.
Once connected, the transmitter was activated with a straight key. This should keep the output power at a constant level.
Testing The KitsAndParts.com SWR Bridge With the Arduino NANO
While transmitting the Forward voltage showed a constant 1 volt and did not fluctuate. The Reverse voltage stayed 0 volts. Since the dummy load Tested SWR this was expected. To verify the Reverse voltage is working properly, the connections to the RF in and out were swapped. Without any adjustments to the SWR bridge, the Reverse voltage reading was very close to the Forward voltage reading.
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This site uses Akismet to reduce spam. Learn how your comment data is processed.As this 'monimatch' type of bridge is frequency dependant, the meter must be calibrated for every band.
Very handy to tune an antenna when you can't have your eyes on the meter while fiddling on the antenna! With my type of bridge some breakout part of mobile radio base station I presume, but working well till 2. With my coupler, in the PEP power measurement mode, it is for example perfectly possible to measure the output of a WiFi access points But is is essential that same power gives same voltage, both in 'forward' as 'reflected' mode when the coupler is turned around.
The meter is indented to be battery powered, therefore there is a circuit to control the LCD backlight drawing a lot of current and monitor the battery voltage.
Forward power is It was compiled with IDE version Using a directional coupler which is not frequency compensated, the forward voltage indicating the power will be frequency dependant. This should produce a readout of VoltFWD, somewhere in the range 0 - or just aboveas the diode voltage drop is added - this is expressed in milliVolt.
Ideally, this readout should be in the range - 'mid-scale'adjust the reference power accordingly. I leave it up to you to implement this in your sketch Depending on your coupler design, it can be required to 'load it' in order to have the output going to ground level when no RF-power is applied.
Off course all wiring to coupler must be shielded and properly RF-decoupled! Therefore, some fields will be empty on the display. To calibrate the sketch, follow the simple procedure below : uncomment the calibration routine lines, this will show the VoltFWD value.