Many thanks to SWLing Post contributor, Marc Thomas, who shares a link to this site which describes modifications to eliminate the Tivdio V-115’s internal noise.
In a nutshell, the author made two small mods:
- Decouple the power/battery with an electrolytic capacitor of around 10uF soldered to the battery connector inside the radio (see photo above)
- The author also grounded the speaker, but didn’t test to see if this alone had any positive impact
I could not find contact details for the author of this mod, so I hope they don’t mind the fact I shared it here on the SWLing Post.
Note that the Tivdio V-115 is also known as the Audiomax SRW-710S and Kaimeda SRW-710S (and likely rebadged as a number of other models).
Click here to read reviews of this radio.
Also the BL5C battery terminal is common in Tecsun PL-330, Radiwow/Sihuadon R-108, Hanrongda K603, and most radios with BL5C battery.
It can be added 10 uF capacitor to reduce internally generated noise.
Website here for the R-108 version: https://www.youtube.com/watch?v=pQjJUCC6-CU
can even try 22uF capacitor like what Mister wiseguy from brazil mafia nerd.
make sure there is free space so that it will fit for the 22uF capacitor (for 50v, the wire must connected otherwise.)
Radiwow/Sihuadon R-108 can support 22uF despite R-108 had capacitor on the PCB to remove noise but the battery terminal doesn’t have this.
remember r-108 battery terminal is on the back side of the PCB that has microUSB. Also it even experimented this noise reduction method on:
Retekess TR601
TECSUN PL330
XHDATA D-328
Tivdio HR-11S
Hanrongda K-603
and most mechanical/DSP radios with BL5C battery terminals
don’t forget tr102 otherwise.
I’ve found on line another remedy for this issue and it’s very, very simple to act: unscrew the 6 screws of the radio, carefully open the radio and You’ll see the black wire of antenna (from the FM-SW telescopic antenna to the “ANT” terminal on the pcb) that is leaning the pcb…. well move this wire on the opposite side of pcb and close the radio…. the noise is disappeared and You can use the radio without issues. The noise is generated from the cable that joins the stylus antenna with the pcb that is leaning ON the pcb and captures all the noise
Just cut and short antenna wire that’s enough friends !
Video instruction
https://youtu.be/cJXS723tgmA
To reduce noise, I’d do the following:
1. Add a separate 32kHz crystal to the DSP. The DSP is currently running on the clock from the MCU. That clock might have higher jitter than the low-noise oscillator of the DSP.
2. Better filtering of the DSP power supply might help too. It’s a simple RC filter, I’d add a ferrite bead or an inductor, and more caps.
No no no! 32 kHz is less. It’s 32 MHz, if you try to install, doing so will cause interference.
According to datasheet for AKC6951(55), it’s recommend to use 12 MHz crystal oscillator (but since Retekess V115 and some bluetooth capable radios running on AKC6951(55) had this bluetooth sensor, try 16 MHz instead for performance.)
for newer v115, dsp chip uses kt0935r an support up to 38 mhz crystal oscillator (SMD). But, i prefer 12-16 MHz since there is no way to compete against interference.
i mean can support up to 38 mhz crystal oscillator (smd)
Just got this little gem radio to play with and there are many good things about it as noted BUT the internal RF noise kills it as a weak signal or even moderate signal listener on MW. I tried the cap across the battery terminals mod and it did not seem to do much. It sounds like the noise is switching frequency stuff coming from the processor that drives the display. Anybody have a mod that will actually solve the problem? Shielding of the display from the RF board??? Thanks.
Thanks for the pointer.
As one who is particularly annoyed by radio-generated hash leaking into the audio, I have returned, resold, or simply shelved more receivers over the years than I can keep track of. I have occasionally made half-hearted efforts at adding grounding and/or internal shielding to radios otherwise headed for the trash heap, but with middling to limited success.
The strategy posted by this user is puzzling to me. The “common knowledge” is that this digital hash most commonly originates in the controller for the LCD display panel. When meticulous component placement or shielding don’t work in receiver design, designers sometimes take a “cop out”. For instance, the CCrane pocket radio dedicates a front panel button to turning the display off as its solution to digi-noise.
So it is quite surprising to see that someone claims to have solved the noise issue in this particular set of models by strapping an electrolytic across the battery terminals. With the above background in mind, the electrical rationale behind it simply does not make sense. Does it really work? To what extent?