There is a page on the web - the author brags about DX results on FM. Today I don't have DX conditions, but in the past I often managed to listen to something interesting - I used a Quad on FM then.
It's worth playing with better antennas, I plan to build an antenna Moxon FM - the author brags about gains, but that will have to be checked.
Ok 9dBi, directional characteristics, but I think it's worth trying.
Yes, this is an interesting design - maybe I will try it out. A question of mechanics - can this be attached to plywood, i.e. won't the plywood material cause some signal loss?
The plywood will not affect the FM signal - maybe at GHz it will have an effect, but not at these frequencies (88-108 MHz). Moxon has an impedance of about 75 ohms, but it is symmetrical, and you would need to make some coils of coax as a balun to match the asymmetrical coax to the symmetrical antenna.
When receiving it is not important whether it has 75 or there 50. If you wanted to transmit from it is another matter. For 50PLN you can buy a Dipol 3RZ antenna, I recommend you to test it.
For receiving FM BC Bands you can connect any good quality and low loss 75 ohms coaxial cable to the driven elements at the middle point of this antenna. No matching is required like balun, gamma, hair pin etc. and therefore no question of matching loss
In a nutshell, you can and do recommend a balun, but Moxon antennas are symmetrical. Lack of matching causes a change in radiation characteristics (in this case reception). A few coils of concentric and it will already be better.
A bit of theory here .
Ferrite on the wire may also help in this case.
I would, however, opt for the Moxon antenna - it gives a gain of 9 dBi (which is 4 dB more than this Yagi 3-element). Some kind of matching 50 Ohm sym. ==> 75 Ohm asym. I would also add. And we'll see how it will compare in performance with my current "omnidirectional" antenna - I have the data in the table and it's for fixed reception, not tropo. Only I will have to put up an additional mast (the second chimney at my disposal I have) and maybe some kind of turntable .
The Moxon has a 5 dB gain relative to a straight dipole, it's such a 2-element Yagi antenna with a bent dipole and reflector, in addition, bifurcated for DC. I'm willing to bet that the Dipol 3RZ will perform better than this Moxon in the same location.
Compare the characteristics - it depends on what you want to achieve. Moxon takes up much less space - that's where the profit is. Easier to make is a 3 element yagi, the real antennas for DX are much more elements and are mainly multi-element yagi, long and heavy.
Preferably both (Moxon and Yagi 3-elem.) and I would compare - after all, the TEF6686 can be used as a signal strength meter - and that's its big advantage too .
Hello, I assembled a TEF6686+Adruino Nano v3 chip during the May holidays. I followed the schematic from github and uploaded the batch to the F602 chip, as that was the one that fit. The problem is that I seem to have an offset bandwidth. My first frequency i.e. 87.6 i.e. PR2 is on 105.95 MHz and is noticeably weaker, it doesn't load RDS, the residue in the band is more like interference. I'm afraid the Chinese have flown the coop, but I prefer to ask still. Attached I add pictures of my implementation and a screen shot of the xdr-gtk along with the frequency spectrum and a link to github and AliExpress
You need to place the TEF6686 close to your router (or other wi-fi source), because the TEF has a very weak antenna on the wi-fi and little range.... Well, and set up everything in the menu in the TEF.... There is very useful information on the FB group: https://www.facebook.com/groups/tef6686dspdxtuner - it is worth searching here .
>>21073940 Solved. I used the FM-DX-Tuner and the original XDR-GTK . The problem was with the quartz configuration, my tef has a 4 MHz quartz and the band offset was to blame. In the configuration file ConfigTEF668X.hpp it was enough to change the value of TUNER_TEF668X_REF_CLOCK 0 to 4000000 . There was still an additional problem with the voltage on the line, quoting Konrad from fmdx.pl from the RadioPolska forum
"The Arduino has 5V logic, while the TEF has 3.3V. Voltage levels of 5V are far beyond the TEF specification and for this reason the internal pull-ups of the SDA and SCL lines in the AVR are disabled in my firmware.
Depending on the version of the tuner module, the pull-up resistors for these lines to 3.3V may or may not already be there. Measure the voltage on the SDA and SCL lines, it should be 3.3V if there are pull-up resistors in the tuner module.
If there is 0V on the SDA and SCL lines, then you need to solder two 10kΩ resistors, one with 3.3V to SDA and the other with 3.3V to SCL (red. 3.3V from adruino nano).
If it still doesn't work, then the capacitors on the SDA and SCL lines may be slowing down the data edges too much.
You can solder them out or change the I²C bus speed from 400 kHz to 100 kHz in the file src/I2c/I2cMaster/I2cMaster.h uint32_t const F_TWI = 400000L; on uint32_t const F_TWI = 100000L;"
I would add that it was not necessary to remove the capacitors on the SDA/SCL line and/or change the IC bus speed.
On the RP forum there was a raised thread about connecting the NANO+TEF6686 set to bluetooth. This way you can get rid of the interference sowed via USB from the PC. I ordered on aliexpress the HC-05 module and plan to power the arduino+tefa with a powerbank. I have a question, is this batch from Elportal enough to paste into the Adruino IDE sketch? I would depend on some batches as there is a lot of this on the net. As I've read some say that you still need to give 1K+2.2K resistors on the RX line, so as to lower the voltage to 3.3V, as the NANO runs on 5V. It is known that I would like to have a serial port and connect via xdr as before. Thanks in advance I am such a beginner hobbyist and so I can ask simple and stupid questions. I don't think I've screwed anything up.
Hello, a month ago the TEF6686 receiver I ordered from Aliexpress arrived. I'm talking about the whole radio, not the head unit itself. I wanted to connect it under the XDR-GTK program, only that after selecting the COM port the program keeps displaying "Waiting for tuner" and cannot connect to the radio. I have version 1.18 of the receiver and hence my query: to connect the receiver to this program, do I first need to update the software? If so, to which version?
I should also add that this is the version with coloured buttons and 2 knobs.
Can I ask for a hint on how to solve the problem of connecting this radio to a TPA3255 digital amplifier - when I connect with a cable, the radio goes stupid. Apparently this digital is seeding The issue is the audio connection from the minijack output.
>>21073065 By accident I connected a 4 x 20.5 m antenna on 4 masts h=7.5 m, further balun and RG-7 cable - and I have reception of UKF stations from almost all over Poland - from Gdańsk to Krosno .
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>>21141873 Yes, it is better to update the firmware of this tuner. There is currently a stable version 2.20. You need to log in to Discord - and they are under Sjef's projects tab.
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>>21142449 Yes, you even need to. There is currently a stable version 2.20. You need to log in to Discord; fw sa under Sjef's Projects .
✨ The TEF6686 AM/FM tuner module, available for around PLN 100 from Chinese suppliers such as AliExpress, is a highly sensitive and selective digital FM tuner with analog audio output (L+R or MPX). It is controlled via I2C communication, often interfaced through an Atmega328 microcontroller that translates I2C commands to UART for PC control. The module supports adjustable de-emphasis, filtering, and RDS decoding, with software like XDR-GTK enabling tuning and signal visualization. Users report excellent reception capabilities, including distant stations and good AM performance, especially when paired with appropriate antennas such as dipoles or directional antennas (Yagi, Moxon). The module requires a 3.3V I2C interface with proper pull-up resistors and a 5V power supply for the microcontroller. Firmware updates (e.g., version 2.20) improve functionality and compatibility. Integration with Arduino Nano or similar Atmega328-based boards is common, with available open-source code on GitHub. Audio output is analog and must be connected to an amplifier or line-in for sound; headphones can work but with limited volume. The TEF6686 differs from simpler tuners like QN8035 or SI4703 by offering superior sensitivity and selectivity, making it suitable for DX listening and antenna testing. Users also discuss antenna matching, impedance considerations, and the benefits of directional antennas for enhanced reception. Some challenges include initial setup, firmware configuration (e.g., quartz frequency adjustment), and ensuring correct voltage levels on I2C lines. Community resources include GitHub repositories, YouTube tutorials, and Facebook groups for firmware, software, and hardware support. Generated by the language model.
TL;DR: With a –120 dBm noise floor, "TEF6686 is a completely different league" [Elektroda, dktr, #19665625; #19659203]. Update firmware, add 3.3 V pull-ups, and XDR-GTK or Wi-Fi control unlocks DX-grade AM/FM up to 300 km. Why it matters: a €20 board can rival vintage hi-fi tuners when set up correctly.
Search “TEF6686 radio module” on AliExpress or similar Chinese marketplaces; prices range from PLN 67 to PLN 100 plus shipping [Elektroda, simw, #19656257; dktr, #19658014].
2. Which microcontroller works best for control?
An ATmega328 (Arduino Uno/Nano) is enough; it translates UART ↔ I²C commands. Any board exposing 3.3 V-safe I²C lines will work [Elektroda, dktr, post #20252114]
3. How do I wire the module to an Arduino?
Connect SDA/SCL through 10 kΩ pull-ups to 3.3 V. 2. Tie module 3.3 V and GND to Arduino 3.3 V/GND. 3. Link audio L/R to an amplifier or PC line-in. Follow the schematic in the first post [Elektroda, dktr, post #19656231]
4. XDR-GTK shows “Waiting for tuner” – what’s wrong?
Older firmware (≤v1.18) uses different serial commands. Flash Sjef’s v2.20 firmware via USB, then select the correct COM port at 115 200 bps [Elektroda, henryk2f, post #21586701]
5. My signal meter steps 1 dB at a time.
Decimal resolution appears only in firmware ≥v2.0. Update the ATmega code from the FM-DX-Tuner repo to restore 0.1 dB steps [Elektroda, dktr, post #20251213]
6. The frequencies are offset by ~18 MHz. How do I fix this?
If your board has a 4 MHz crystal, set TUNER_TEF668X_REF_CLOCK to 4000000 in ConfigTEF668X.hpp and recompile; the spectrum then aligns correctly [Elektroda, bup00124545, post #21075906]
7. Can I hear audio through XDR-GTK alone?
No. XDR-GTK only sends control commands. Route L/R outputs to an amp or enable “Listen to this device” on the PC line-in mixer for monitoring [Elektroda, dktr, #20246285; lechoo, #20247886].
8. How sensitive is TEF6686 compared with QN8035 or TEA5767?
Tests show stereo locks at –91 dBm, RDS at –75 dBm, beating QN8035 and TEA5767 which fail under –65 dBm adjacent-channel conditions [Elektroda, dktr, #19659365; #19665625].
9. Does it really handle AM longwave and medium-wave?
Yes. Even with an FM dipole it received 225 kHz LW and city-noise MW signals; adding a proper loop improves clarity [Elektroda, dktr, post #19684703]
10. How can I use the tuner over Wi-Fi?
Install xdr-gtk on a Raspberry Pi, forward UART via TCP, and stream audio with foobar2000; public demo at dktr.pl shows <1 s latency [Elektroda, dktr, post #19656231]
11. Nothing shows without an antenna—is that normal?
Yes. With input shorted, meter rests near –120 dBm. Attach a tuned FM antenna to see stations; an unmatched wire yields negative gain [Elektroda, dktr, #19665625; #20772781].
12. TPA3255 amp makes the tuner “go stupid.” What can I do?
Digital amps radiate HF noise via the audio cable. Add ferrite beads on the minijack, keep grounds short, or use an optical isolator; after filtering, the tuner regains stability [Elektroda, bendix101, post #21585259]
13. Can I lower USB noise entirely?
Power the Arduino+TEF from a battery bank and replace USB with an HC-05 Bluetooth serial link; level-shift HC-05 RX to 3.3 V using 1 kΩ+2.2 kΩ divider [Elektroda, bup00124545, post #21075906]
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I am such a beginner hobbyist and so I can ask simple and stupid questions. I don't think I've screwed anything up.
The issue is the audio connection from the minijack output.
