Unbricking a Pair of ATS25 Receivers

Back in January I was approached by a member in one of my ham radio clubs that wanted some assistance with a pair of ~$100 ESP32 microcontroller-based shortwave radios he picked up on Amazon.  He passed them over to me and after initial inspections I was rather confused.  I managed to learn how to update the firmware they run (using Arduino IDE), and was able to flash all sorts of software versions, but I was never able to get them to boot up.  They would hang on the message "Si473X addr: 63." I asked in an online forum about the issue but got no replies.  At this point, the best I could figure is that there was a hardware failure of some sort, either with the ESP32 controllers that run the radios or the Si4732 chips that live at the heart of the radio.

I reported back to the owner that I was suspecting a hardware failure, but I had no way of knowing exactly what part it was without being able to swap a couple things with a working one.  He decided he would cut his losses and move on.

Fast forward a couple weeks and I needed to put in a Mouser order for another project and have a few extra dollars in spending cash, so I ordered a pair of ESP32 boards and a pair of Si4732 chips to experiment. I started with the easier part to replace - the Si4732 and after using my hot air gun to remove the old one, cleaning the pads, and hand-soldering in a replacement, I turned on the first one and it booted right up! I repeated the process for the second one and fixed the both.  This was my first ever successful surface-mount IC replacement attempt.

I reported back to the owner what I managed to do and worked out a trade so one goes back to him, I keep the other one.  It was at this point that I found out that he (at separate times) had these on a coax switch to share one antenna between several radios and was running an HF amplifier thru the switch.  Looks like the RF leakage in the switch fried the chips in the ATS25 receivers.

Hopefully this post will be useful to someone that runs into the freezing on the "Si473X addr: 63" message.

73 everyone.

Realistic HTX-100 Blinking 28.000 - Fixed!

I picked up a broken Realistic HTX-100 at a hamfest for cheap a while back and wanted to share what I found for the repairs.  The symptom I had was when powering it on, it would just blink 28.000MHz and none of the controls seemed to do anything.  I did some searching around and based on text searches only found old posts saying to send it in somewhere for repairs.  Obviously, these have been long since out of production so that is not a likely repair. My initial guess was a PLL unlock due to bad caps on the PLL board, but that guess was wrong.  I stumbled across a YouTube video about a failed repair of one that had a very similar symptom.  The person that made the video was not able to conclusively determine the fault as the radio started working more or less on its own, but he mentioned finding a metal fragment that fell out of the front switches and noted that if the PTT is held down when the radio is powered on, it will blink the last frequency it is set to and act like it is locked up.

This was as good of a starting point as any for me, so I set out tracing the PTT circuit and found that if there is no 8v going to the front display board it will invoke the PTT line. Long story short, I found a vaporized trace by the 8v regulator and a shorted capacitor (capacitor pictured below).  When the capacitor shorted, the PCB trace burned up like a fuse and took out the 13.8v supply that goes to the 8v regulator. This was capacitor C163 on my rig, but there are others that could short and cause a similar issue as well.

When trying to tack down where the shorted component was, I found it useful to use the PCB jumpers as "divide and conquer" points.  I would pick one, de-solder one side and see which side of it the short was.  Otherwise, you just end up scratching your head wondering which component in that part of the circuit could be shorted.

I'm sorry for not taking detailed pics as I went along, but I hope that someone may be able to find this useful in case they have the same symptom on their HTX-100.

Thoughts on the Anysecu WP-9900 mini mobile radio (AKA the QYT KT-9900 or KT-WP12)

Last weekend I picked up an interesting dual-band mobile radio used at a hamfest.  It is the Anysecu WP-9900, which is also branded as a QYT KT-9900 and QYT KT-WP12.  A cursory search online seems to have very polarizing reviews of it with some loving it for its unique form factor, and others despising its quirks, and difficulty in getting it programmed. After fighting to get it programmed, I felt compelled to make a posting on it in case it is useful for others in the future.

 

The first topic I want to touch on is the waterproof claims that some product listings indicate.  In short, its a load of phooey.  The mic connector is not a watertight seal.  I find the design of all the rubber seals to be somewhat perplexing to me, though it does make for some pretty good dust protection.  The case is a metal casting, but this seems to be more so that it can double as a heat sink rather than being a premium build quality.

The next item of note is the reports of not being able to get the programming software installed, let alone working.  I can confirm that the one that is downloaded from Anysecu's website is a real pain.  There is no installer for it, and it requires some DLL files that you would need to hunt down separately.  It seems like they made the programming app in Visual Basic 6.0, which has been obsolete for an extremely long time, but there's a project over at SourceForge that can install the needed runtime files.  The program from QYT's website has an installer, and also included the required runtime files, so easy going there.  Sadly, there is no support from Chirp at this time.

In regards to actually using the software, its not hard to figure out if you have used other similar programming applications.  It is extremely confusing if you have not, and not having a help file (yet bizarrely still having buttons for one) doesn't make matters any better.  I do like how when you type in a receive frequency, the transmit frequency if it were simplex will auto fill.  Similarly, if you type in or select a receive PL (CTCSS) tone, the transmit tone will also auto fill. It would be nice if there was an option to have the auto fill values correspond to repeater offsets. I like having the NOAA frequencies programmed in my radios, but I don't want to be able to accidentally transmit on them (sadly, many Chinese radios allow this, even though I would consider it to be an extremely dangerous oversight).  I found in the software that you can delete the frequency in the Tx column and leave it blank to have a channel be receive only.

The programming cable is another story of its own.  As I purchased mine used, I did not get the programming cable.  I figured this wouldn't be a big deal as I had an 8-in-1 programming cable.  Unfortunately, while that cable has the right connector, it isn't wired for this radio.  Googling around didn't lead to anything concrete in regards to what the pinout is, and the article about a 3-pin programming cable on Miklor's site led me down a rabbit hole of red herrings.  When I followed that pinout, my radio would restart when attempting to read from it, and following the suggestion of adding the two resistors led to the software saying there was a com port error.  It should be noted that I made my cable from a Baofeng cable that happened to have one of the counterfeit prolific chipsets in it, though it was known to work just fine in Linux.  Ultimately after trying several computers, I ended up using the wiring pinout shown in the picture below on a Windows XP computer (using the 2.0.2.1 diver version). The connector for the radio is a regular 3-pin 3.5mm (1/8") stereo aux or TRS (Tip Ring Sleeve) connector. You can't use a 2-pin mono or 4-pin TRRS headset connector.  You could also try your luck buying a standard QYT programming cable.

 

In regards to programming it, I have seen several comments on forums and such that state you have to read from the radio, then edit the data that is read, then write that back to the radio.  I found that I was actually able to generate my own frequency file before ever getting a working programming cable made.  I used the software from Anysecu's web page, and then ended up using the software from QYT to actually upload that same file to the radio.  I did read the data in the radio before I wrote my own file, though, so it may indeed require a read operation to be run before a write operation can take place.  One other thing of note is that for the channel name, you are limited to 6 characters.  This is just enough for a standard 2x3 US call sign, but not so great if you want to use a descriptive name.  I opted to just go by frequencies since I have several repeaters in my area that share call signs.  I have also read that the radio will end up in either boot loop or the software will crash if a channel name longer than 6 characters is entered.  I would have expected the programming software to prevent this, but apparently not.

All in all, its a decent radio for what it is (a cheap dual band mobile in a unique form factor), once you get the programming sorted out.  I don't regret buying it, but I wish I had some clear documentation on the programming side of things, it would have saved me a lot of time.

 If you would like to pick up one of these radios, please consider using this eBay partner link to help me out a little: Anysecu WP-9900

73, and stay radio active!