RDA1846, the transceiver inside Baofeng UV-5R, Yaesu FT-4XR, SA818 and other radios is no longer manufactured. There are equivalent chips that can be used.The most known are AT1846S and write something which both are pin-to-pin compatible with RDA1846. Unfortunately, none is available JLCPCB parts. At least for now, and that is important if I have any intention to design something that I wish to be mass produced. However, some time ago a friend of mine who buys all kind of things from AliExpress gave me ten AT1846S to use in various radio prototype projects. Up until now I did not use these but I had some ideas what I can do with them, from echolink-like radio nodes to beacons and repeaters. However, I did not have the time to start any project. One of the hurdles I faced is the fact that these come in QFN32 package which is a pain to solder manually.
A couple of weeks ago I decided that it is time to use these for something. As I am running out of SA818s I want to find a way to design radio projects based on these chips and not on SA818. However, these are QFN32 and soldering these chips is a pain because the contacts (pads) are on the hidden side of the device. Designed for reflow soldering, QFN packages are not very friendly for hand soldering and I miss the skills and experience to do this myself getting perfect results. I tried and this is my first attempt at soldering using a hot gun:
However, I am sure I can get better results. I need to buy some high quality flux and rework this until I get perfect (ish) results. Anyway, once this is done, I will start testing and have it connected to a microcontroller for programming (RDA1846 and equivanents are programmable. See here for the programminng guide).
If you need, there are some good online resources about SA818. But I will not recommend new designs with this. SA818 is a nice and comfy device but is a crap device from the emission spectrum perspective. Maybe I will post an article with some measurements.
More information here:
- Nice-RF SA818 page, then here
- AT1846S register table on GitHub, OpenRTX project
