QCX 5W CW Transceiver - 40m
QRP Labs QCX 40m 5W CW Transceiver
A QRP Labs QCX 40m 5W CW Transceiver kit and an QRP Labs enclosure Kit was started around MAR18 getting halfway through the assembly when having to packing things for moving to another temporary house in MAY18. Somehow, the kit was not completed since being consumed with looking for a new residence with my wife, Denice, and working (my wife and I sold our northern VA house and were looking for another house in the Colorado Springs area living in two rental houses during the 5-6 months). Then with still working at that time, Denice's health for too many months, and getting into a new place with all of the unpacking, nothing happened with getting it out and restarting the kit's assmebly. It was finaly upacked, on the bench, and most of the remaining assembly and testing done. The kit was finally completed in JUN21.
In-progress with the initial assembly. This MAR18 picture was a bit after starting the kit. did not get too much further with the assembly until packing-up everything for moving from one temporary house to another.
Tyring to figure-out what I was thinking of for controls and connectors mounting and the wiring (for the controls and connectors on the enclosure's end panels and how they will connect with the PCB). Still have yet to wind and install the toroids. Picture from DEC20.
Further along in working-out the details for the enclosure's mounting and for the wiring. The toroids have been wound along with being installed.
All done with the mounting and wiring. Unknown to me at the time, the initial "power on" testing would be quite a long time in the future. Still have to install the PIC....
Testing the QRP Labs QLG1 GPS receiver after completing the assembly. Had a quick and good lock on GPS satellites from right there on the bench.
Showing the headers taking the signals from the main board to the display board. The problem was that it was not right with the display orientated now being upside down. The display being upside down not being noticed until that first power-up.
Note: The board assembly at he bottom of the picture is the QRP Labs 20W Dummy Load
Looks good, but not right. I also did not have any power for the display's illimination.
Discrete wires taking the data from the main board to the display board. The display board is also mounted correctly in the front panel.
The small RF test board was made from a small piece of single-sided PCB that I had on-hand, a piece about 25 x 60 mm. A razor saw was used for separating the foil in half lengthwise, and then taking one of the two halves to further make 7 distinct “pads”. The end “pads” were then further reduced to make a “strip” for the center conductor of a SMA PCB connector to solder to. A DMM was used to verify the cuts were complete – that no two adjacent sections of foil remained electrically connected. The fixture was then tinned along with the connectors being soldered on.
Of particular interest were the toroids L1, L2, and L3. L1 and L3 were found to have 21 turns as they should have had and L2 had 24 turns as it was supposed to have. The following was the nominal (as per the QCX’s assembly instructions) and measured values for the toroids:
The QCX’s LPF appeared to have a 0.32 dB insertion loss. In the screenshot, the SpecAn’s frequency is set for 15.0 MHz, the span set for 20 MHz, and the TG set for -20 dBm. The attenuation at 14.1 MHz was over 40 dB. Somehow, I neglected to get screenshots of the 14.1 MHz marker and the 3dB bandwidth (BW).
A quick test of the QCX assembly was done as a “sanity test” after getting it back together. I was still unsure “just why” not getting a bit more signal output from the QCX. I was only getting around 38.7 Vpp which is a bit lower than the ~41 Vpp when working on the QCX+ kit. Other than that, I am pretty happy with the way things are for now.
The frequency calibration was attempted once again using the QRP Labs QLG1 GPS module. Was confounded by it when starting menu item 8.11, Cal Ref Osc, seeing the sequence of “Waiting, 6, 5, 4….” And then seeming to be stuck on “4”. Found in the “groups.io” QRP Labs group that I should have had the unit set to practice mode with menu item 4.7. Also messed with menu 6.1 too a bit. Once that was done, it was switched back over to menu item 8.11, Cal Ref Osc. After playing with it a few times, I finally was able to see the entire sequence complete for the first time. I then switched over to menu item 8.12, Cal Sys Osc, which completed quickly.
In some comparison testing, a CW QSO being received on the QCX was checked against what was being heard on the Kenwood TS-990S – the QCX seemed to be “right in there” being on-frequency along with tone and received signal strength for what was being heard and seen with the TS-990S. The QCX was connected to my 80m NVIS antenna and with the TS-990S connected to the Zero-Five 10-40m Ground Plane Vertical antenna.
Just prior to putting the cover on…
…and with the cover on and ready for use!