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Technical Topics => Equipment => Topic started by: syfr on April 01, 2021, 2219 UTC

Title: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on April 01, 2021, 2219 UTC
https://www.amazon.com/Receiver-Airband-Portable-Handheld-Recorder/dp/B08ZDHT7LY/ref=psdc_172653_t2_B08Z8L9ZYZ (https://www.amazon.com/Receiver-Airband-Portable-Handheld-Recorder/dp/B08ZDHT7LY/ref=psdc_172653_t2_B08Z8L9ZYZ)

Anyone seen any reviews?

It's cheap enough I might take the gamble. After all:

Application: Si4732 radio receiver suitable for outdoor camping, listening to radio music in the kitchen, it is a necessary condition for participating in the parade and family life
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: ChrisSmolinski on April 01, 2021, 2311 UTC
The guts of the radio is the SI4732 IC, which basically does all the RF stuff: https://www.silabs.com/documents/public/data-shorts/Si4732-A10-short.pdf

Lots of variants of the radio on eBay as you may expect.

Or buy the IC and build your own! https://www.mouser.com/ProductDetail/Silicon-Labs/SI4732-A10-GS?qs=p9T7GgSe1IFCUks4Oy6aSA%3D%3D

Cheaper here https://www.semiconductorstore.com/cart/pc/viewPrd.asp?idproduct=55203
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: ~SIGINT~ on April 01, 2021, 2312 UTC
I don't know, it looks pretty sketchy to me. Not even any pictures with the unit powered on so you can evaluate the display.

Plus; what is that FM/AM(SSB) recessed switch by the antenna input connector?
No run-time on the battery;
"FM supports earphone antennas" --- maybe that's what that switch is, use the earphones as a FM dipole?;
"PCB retains the SI4735 package, users can replace the chip by themselves, and the software is compatible." What you talkin' about Willis?

I could go on and on here. No thanks. $68.69 + $99.00 shipping to Canada. Forget it.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on April 02, 2021, 0038 UTC
Found a review or two on Youtube...one even in English. Might give it a go. I saw that note about replacing the "chip" (what?!) .

As usual , there's the general clunkiness of operating all radios with few knobs but a lot of buttons (whether it's Icom or NoNameesium)
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: ~SIGINT~ on April 02, 2021, 0104 UTC
If you do end up with one I'm sure we would all be curious and like to hear about it.

If you are not interested in the FM, air band stuff, I.E. shortwave only, you can't go wrong with the BELKA-DX. I have had one since last November and it is a great little box. The only "I wish" thing about it is if it was not limited to 1.5 - 31 MHz. Like most BELKA users, we wish it went down to 500 kHz to cover the AM band. Even if it tuned down to zero with reduced performance I would be ok with that. I have slipped that radio in a coat pocket with earbuds on and had "HF on the move" listening to broadcasts while taking a walk. I even take the radio on bike rides down the trails and stop for 10 minutes or so and DX from various locations. I'm truly having a blast with that radio.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: redhat on April 02, 2021, 0356 UTC
Why the interest in this, form factor perhaps?  I would guess this is the chipset used in all the Chinese cc radio clones?

+-RH
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: NJQA on April 02, 2021, 1030 UTC
While they say this is an “Airband” radio, none of the Amazon sellers, nor the SI4732 data sheet, show that it has coverage of 108 thru 136 MHz.  I guess they mean the SW aviation frequencies, not the VHF ones.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on April 02, 2021, 1108 UTC
I have one on order via eBay. It could take awhile to arrive from China. I will try to remember to post some feedback here. :)
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: ~SIGINT~ on April 02, 2021, 1255 UTC
You can follow this post for further details and reviews.

Any thoughts on this inexpensive Si4732-based receiver?
https://swling.com/blog/2021/04/any-thoughts-on-this-inexpensive-si4732-based-receiver/ (https://swling.com/blog/2021/04/any-thoughts-on-this-inexpensive-si4732-based-receiver/)
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on April 02, 2021, 1353 UTC
Copy-and-paste from my SWLing post....

The Si4732-A10 probably is close to the Si7435-D60, assuming it is not essentially the same architecture in a different package format with a lower voltage threshold.

So if assuming they are similar, Silicon Labs has actual Si7435 tech specs here:

https://www.silabs.com/documents/public/data-shorts/Si4734-35-short.pdf
https://www.silabs.com/documents/public/data-sheets/Si4730-31-34-35-D60.pdf

If someone wants to open there radio to confirm before mine arrives, I suspect it might have a DCCduino Nano inside. Perhaps even with a CH340/CH341, (likely counterfeit) FTDI, or similar USB comms chip; which could open up more possibilities for those wanting to experiment with the radio code.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on April 04, 2021, 1735 UTC
Marc at swling noted it reports a HL-340 USB-Serial adapter when probed under Linux.

Looks like we might have a potentially rather hackable radio assuming it proves popular enough.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on April 24, 2021, 2046 UTC
Reviews are starting to appear and they're not good.

I ordered a Belka (whose reviews are quite good!)
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on April 24, 2021, 2331 UTC
It is a project radio, and that is how I went into the purchase. Think more or less an assembled kit, and you get to "fix" it to some usable state.

Still waiting on mine, but I did get shipping info recently, so maybe it will arrive in a couple or so weeks.

I did a quick skim of a Si473x community awhile back. Somebody was working on software. Spotted info about cleaning up and stabilizing a similar (or same?) design with filtering caps.

Assuming mine even works at a basic level, I intend to add more power filtering, basic ESD protection, and perhaps some type of input matching.

All that said.... yeah, definitely instead buy a known decent radio if actually wanting something usable out of the box. :)
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 10, 2021, 1949 UTC
Received mine earlier today. Connected it to my 9' vertical, turned it on, and skimmed some frequencies.

Sounds decent on AM and FM broadcast bands. Plenty of volume. Has several bandwidth options, multi-step attenuation, etc.

The VFO feels about the same as a basic portable. AFAIK, it is only soldered to the PCB, so that probably needs some reinforcement. Especially if pushing on it for the SSB BFO and whatever else it does.

I have yet to open the radio for a quick look. Maybe later today. At minimum it is likely getting a couple of diodes for basic ESD protection, then I might look into adding a few filtering caps on the internal power rails.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 16, 2021, 0021 UTC
Still have yet to open the radio, but I did get around to updating the software.

https://github.com/pu2clr/SI4735/tree/master/examples/SI47XX_KITS/AliExpress

Much better user interface now. :) Other changes include being able to tweak or disable soft mute, finer grained attenuation, and a few options being moved to the encoder instead of multiple button presses.

Currently using it to listen to a 40m SSB net via the 148' LoG. Sounding and performing about the same as any other SI473x portable in the sub-$100 segment IMO. The SSB highpass is a little high for music, thus losing some lows, but generally okay for voice comms. The internal speaker response seems rather narrow anyway. Of note I actually like the form factor. I have been using it as a small secondary receiver on top of my Kenwood R-2000.

I plan to drop in a 1M resistor and a couple of diodes for at least basic ESD protection. After looking through my parts, I had to order the diodes, so I will take a closer look inside after receiving them.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on May 17, 2021, 0000 UTC
I'll be watching your progress.  A software "kit" is a good way to look at it.   

Please keep posting what you find, it's much appreciated.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 17, 2021, 1657 UTC
Thanks and will do. :)

Copy-and-paste about the latest firmware update:

Quote
* The final code (HEX file) is about 2.5K smaller than the previous one (now you have more memory to add new features);
* Twenty three bands. Two VHF(FM); one LW; two MW; and Nineteen SW bands covering from 1800 to 30000 kHz;
* Band, Volume, Step, Bandwidth, AGC/Attenuation are now controlled by encoder;
* "Vol-" buttons is free to implement new features. It has no function for while;
* "BAND-" now is used to control Softmute Attenuation;
* All the previous status of the receiver can be rescued when you turn it on (including SSB mode, bandwidth, volume, frequency, BFO etc);
* The bandwidth now is a property of the band (you can use different bandwidth for different bands);
* Bandwidth control on FM mode (Auto, 110, 84, 60 and 40 kHz);
* Bandwidth control on AM mode (1, 2, 2.5, 3, 4 and 6 kHz);
* Bandwidth control on SSB mode (0.5, 1, 1.2, 2.2, 3 and 4 kHz);
* AGC (Automatic Gain Control) and Attenuation control;
* Softmute Attenuation Control;
* FM/RDS presentation was improved;
* The seek function was improved (it is more precise on FM mode). The seek direction is controlled by the encoder (clockwise or counter-clockwise. Press encoder push button for seeking Steps: 1, 5, 9, 10, 50 and 100 kHz;
* Now you can configure MW band space to 9 or 10 kHz;
* New FM band from 64 to 84 MHz;
* New MW band from 531 to 1701 kHz for Europe, Africa and Asia;
* The frequency on Display is bigger than the previous version;
* Now the bandwidth sequence is ordered by bandwidth values;
* After about 4 seconds, all command buttons are all disabled and the encoder control goes back to the frequency;
* The current status of the receiver will be stored only after 10 seconds of inactivity.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on May 17, 2021, 1939 UTC
That's cool, and a lot of changes. Are they managing the changes through Git or something similar?

I'm pretty sure you must be better at working with downloading/building firmware than I am .   :-)
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 17, 2021, 2012 UTC
PU2CLR maintains a git repository for SI47xx software:

https://github.com/pu2clr/SI4735

The specific firmware I am using:

https://github.com/pu2clr/SI4735/tree/master/examples/SI47XX_KITS/AliExpress

There also are groups for the SI47xx chip in general:

https://www.facebook.com/groups/532613604253401/
https://groups.io/g/si47xx/topics

I poke at and build* software casually, but I am not really into the Arduino stuff, so I had to install the IDE.

I was just following the directions. Thankfully no command lines, git commands, or complicated steps. The IDE itself pulls in all the needed parts from an Internet database. Basically search, install three libraries, click a few options, then upload to the radio. If anyone does it, definitely remember to hold in the encoder while powering the radio to reset the EEPROM after the firmware upgrade.

I did glance at the source. It is well laid out and commented if one wanted to change things such as button assignments or whatever.

*One of my other hobbies is optimizing and building the Chromium web browser.

https://chromium.woolyss.com/
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 17, 2021, 2017 UTC
For the more adventurous, apparently a dev even has added a CW decoder to his firmware.

http://www.cqham.ru/forum/showthread.php?33038-Elektor-DSP-Radio-%ED%E0-%F7%E8%EF%E5-Si4735&p=1828648&viewfull=1#post1828648

I am somewhat surprised it fit. The Arduino Nano - well, it is a clone here to be technical  - only has like 30KB of usable memory.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on May 17, 2021, 2232 UTC
Thanks for the good info. I can use the IDE ok, and I'm good at following the bouncing ball instruction-wise, but it doesn't take much to happen to put me out into the weeds.  I'm one of those eternally grateful for installation packages.

Yeah, there's not a lot of extra headroom in a Nano, so it's cool they got a decoder packed in there. I've never seen one work very well under real world conditions, but it's fun to play with them.

Cool toy for small bucks it seems like.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 17, 2021, 2319 UTC
I have one these....

https://mfjenterprises.com/products/vec-162

....on a shelf collecting dust. Been there for years. It might be better for RTTY and whatever, but yeah, I agree CW can be quite a YMMV situation in my experience.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 18, 2021, 1618 UTC
I have uploaded several photos of the receiver internals:

https://imgur.com/a/Gl3MLGA
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 18, 2021, 1645 UTC
Antenna path closeup:

https://imgur.com/a/8ODg9YB

Caps are there, so at least the antenna jack is not straight to the chip. Still, no matching inductors or ESD protection.

I am not too concerned about the inductors, as I am not trying to match the included whip antenna.

I expected the lack of ESD protection, as IIRC, the chip SI recommends is like ~$1 a piece.

Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 18, 2021, 2003 UTC
I did not spend much time delving into the design. I just went with the quick-and-dirty approach of throwing parts at it. ;)

https://imgur.com/a/Tn7VvpR

Those are 47uF electrolytics and .1uF ceramics on the Arduino Nano (clone) power rails.

Crossed 1N4148 diodes and a 1M carbon resistor at the BNC connector.

BTW, yeah, my soldering "skills" are horrid. I do good to type sometimes; less long solder anymore.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on May 20, 2021, 1929 UTC
Hey, if it works, and is reliable, it's all great once you button up the case.   It looks good to me.

Hopefully that'll serve to lower some of the noise on the 5V rail. Nice work!
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 20, 2021, 2104 UTC
Thanks. The receiver still works, so at least that is something. ;)

IIRC, all the power pins - except the USB port of course - at the Arduino Nano clone read around 3.x volts. I suspect the control board and Si chip are being run at ~3.3v operation.

The Si4732 is rated down to 2.7v, and apparently the Nano's controller can go down to 3.3v or perhaps lower without much issue, especially if it is not being pushed hard.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on May 20, 2021, 2119 UTC
Hardware hackery that still allows an assembly to work after the soldering iron has cooled, goes into the + category. It's SO easy to wound these things.  Good work on keeping the smoke inside!

Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on May 20, 2021, 2217 UTC
I could have tried adding similar filtering at the USB port or voltage regulator(s), but I left those alone for now due to soldering on smaller pins plus not wanting to accidentally disturb the ability to USB flash firmware. I know a random USB charger was rather noisy on MW+HF as expected. I have been using it on battery power, though no real idea on runtime as I have been charging it between uses instead of letting it run down.

I have thought about looking into a speaker replacement as it seems rather narrow. "Okay" for talk and voice comms. Not so great for music, though admittedly that might be more a function of the audio circuit than the speaker. Suppose I should get around to hearing how it sounds with headphones to get a better idea.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: syfr on May 23, 2021, 2242 UTC
Article and FB (ughhh) group re: new software for this thing:

https://swling.com/blog/2021/05/si473x-receiver-firmware-update-and-internal-photos/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+TheSwlingPost+%28The+SWLing+Post%29
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on July 12, 2021, 1905 UTC
An "ATS-25" touchscreen version recently popped up on eBay and similar. I tossed Thom a line, which he posted here:

https://swling.com/blog/2021/07/the-new-ats-25-si4732-receiver-with-color-touch-screen/
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on August 19, 2021, 0820 UTC
Interestingly enough my "ATS-20" still is working, even after shoving 12vDC down the antenna connector by accidentally hooking up a power inserter for an active antenna backwards. :o The inserter simply blew its internal fuse. Not sure it would have been that simple without the ESD mods done.

Also, I have not been tossing it around much like a typical portable radio. It is usually on a shelf or on top of my R-2000 on the nightstand.

Have it tuned to 75m for background noise right now. Current antenna is my 148' LoG.
Title: Interesting Chinesium SI4732 Shortwave/FM
Post by: Ray Lalleu on September 09, 2021, 1311 UTC
While they say this is an “Airband” radio, none of the Amazon sellers, nor the SI4732 data sheet, show that it has coverage of 108 thru 136 MHz.  I guess they mean the SW aviation frequencies, not the VHF ones.
'Airband' means 108-136 MHz.
Not on that radio !
Please moderator, remove 'Air' from the subject.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on September 11, 2021, 0307 UTC
I suspect it was intended to mean HF aeronautical, then again, most of the bulk "Chinesium" electronics resellers often do not have much a clue about the tech specs of what they are selling anyway.

Edit: Oh yeah, as of last check, my ATS-20 still is working. I think it is on V3.0.7c firmware, which is a revision behind, so I need to get around to flashing an update.
Title: Re: Interesting Chinesium SI4732 Shortwave/Air/FM
Post by: RobRich on October 03, 2021, 0012 UTC
Spotted perhaps a later revision. It has a ground wire from the front panel back to the main PCB for (AFAIK) "display stability." Not seeing one in my pics, and I do not remember one being present. Suppose I will add it when next opening the radio.

Ordered extra encoders and larger knobs, too. Mine still is working, but cheap VFO encoder is a known trouble spot. I might as well change the small VFO knob if/when going through the replacement effort. Sourced via AliExpress, so I might get them in a month or two. Anyway.