The first one I got it as a present from my friend Dexter, YO3HEX.
Came in a lot of envelopes as a kit and, as I am always ready to make some soldering smoke< i was eager to get it done and working!
It was the version for 40m and it was FW revision 1.0 (bear this in mind!).
I did it in one afternoon, eager to make first contact with this little toy and, to my pleasure, it works from the first shot perfect!
It passed too much time to remember what was my first contact with QCX, sorry.
Short time after, another friend of mine, YO3ISL (good to have friends!) made me a nice case on his 3D printer. Mine is sitting nicely on my desk at my workshop...
Years goes by and another (third) friend, YO3IHG bragged about a QCXmini for 20m band. I asked him if it is not for sale and he said "NO but I will let you know if it will be". So, the hope stood by till a couple of weeks ago when he announced me that he will sell it.
A quick negociation and the little radio was "enroute" to me, me being at my second location where my lab is very minimalistic.
Still, I got my two hands, a pair of nice magnifiers and some other tools enough to start assembly the kit.
I received also the optional components to make it uSDX but I am not a fan of SSB with 5W so I decided it will be CW only, a true QCXmini!
I assembled it but, to my surprise, nothing!
Nothing, I mean NOTHING! The LCD was not lit, some bars on the first row and that's it! Nothing more!
No DITs, no DAHS, no hiss on the headphones!
Brick dead!
After some time thinking, an ideea came out shining in the darkness of my room!
Let's change the microcontroller from the QCX 40!
Yup, with the old microcontroller, the little QCXmini got alive!
But only on receiving... No Tx!
Well, hrd time ahead!
I proceeded to measure around the Q4-Q6 Key shaping and soon I found out that the Q6 is no more a valid PNP. What to do? Of course, canibalise the QCX, take the MPS2907 from it and put it to QCX mini. But still nothing. Oh my God, could be Q1-Q3? Well, for this I must go back to Bucharest, 90 km South because there I have all I need to test them.
Still, in my junk boxes, no BS170 as far as I remember... Well, no problem, in the way I will stop at a well known electronic parts shop and take what I need. Checked on their website and they have the through hole BS170 at a fair cheap price.
Got home at 3 PM and put everything in place to start troubleshooting almost immediatlely! Yes, at least one of the BS170 was not OK so I decided to change them all.
Changed them and everything was OK, the TRX got alive and i mean, ALIVE!
I did a full reset and make it to work on 20m, aligned the radio and connected to my balcony antenna (middle of the city, ugh).
I tuned into a strong CW signal and did my first QCXmini QSO with R3OM.
I confess, I was a little bit surprised when he answered me, my antenna is not so great but those Russian CW ops are damn good!
But I still had one problem! It's name was AT328P, the bad microcontroller! I still use the one from the other QCX making it inoperable!
So, I checked into my junk box and found a few ATMEGA AT328P microcontrollers, I got the FW from internet and put it into my homemade programmer and burned the FW into it.
Then move it into the QCX and to my surprise, "USE ORIGINAL IC" message appeared onto the LCD!
From 9 PM to 11PM I was trying to figure out what is wrong there, how to programm the circuit and I already started to contemplate the purchasing of a new IC from QRP Labs. I wasn't OK with this option because of the time required so I took another path. The hard way!
I started to think how the chip could be protected and how to circumvent that protection.
I also sent a message to Vlad, from which I bought the radio, sent him my "nice thoughts" and a few "greetings" and asked him to contact the manufacturer for further instructions.
Meanwhile, I start to wrestle with the little cocroach!
I will not enter into details as I respect the reason for why that protection is there but, at some point, I managed to write an older firmware into the blank IC and the QCX came alive! It was around 1 AM and untill 3 AM I was trying to put the latest FW into it! With no success! Something was wrong and I finally found out what!
On my programming board (designed as a simplified Arduino UNO board), the RESET pin was connected to a 10 uF capacitor which prevent it to correctly load the HEX file. Took it out (cut it with hate) and voila! the things went smooth!
At 4 AM, the QCX Mini was loaded with the latest firmware!
In the morning, Vlad announced me that he got the recover instructions from the manufacturer for a blank chip... Which was nice from their part and got my deepest respect!
OK, what about the yellow QCX, someone would ask?
Well, I couldn't find the original transistor MPS2907 here so I ordered a BC638. This one have the advantage of more CE current (around 1 Amp) but the disadvantage of a ECB topology instead of EBC like the original one! Put the new one and the 40m band QCX is alive and well! Oh, I forgot to update the firmware when I was at Bucharest and I still have the 1.0 FW in it!
No problem, it's OK!
