I DREAM
I need a new project. So how about... a QCX+ 5W CW transceiver? And learning CW??? Or just doing WSPR TX to monitor my propagation???
So the package arrived, ahead of expected delivery time.
Package in post
IN THE BOX?
I opened it up. Wow. Impressive. Excellent quality of components. Beautiful panels. I will drill an extra hole in the back panel eventually to feed out the raw IQ Tayloe audio signals to an SDR program like HDSDR. (which I have running on WIndows 10 under Parallels on my Mac Mini). Connection will be via a USB soundcard plug-in dongle MIC input.
Contents!
What a pile of bits and pieces. I had not expected so many, nor such a complex PCB. This will take some time to assemble, even though I am a quite experienced builder...
GETTING READY TO WORK
My build station, with ELAD FDM-DUE SDR for FT8 contacts
and Macbook for instructions
THE DREADED COIL
The coil 39 + 5 + 5 + 5 turns
Phew, have a long rest. No need to rush it. This will take days...
THE PCB
Time to have a look round the PCB and mount some intitial pieces, start with the ICs
Coil and some ICs fitted
Onwards an upwards...16 x "104" CAPACITORS
Most capacitors done, starting on the resistors. On these Chinese blue background resistors it is quite impossible to read the colour code - need to check every one with a meter.
Scattered all over the board are 16 x "104" decoupling capacitors. These are next to install.
A note: the capacitors come fix along a cardboard strip, just cut them off, there will be plenty of wire left for mounting, don't try to tear them off the mounting strip this will just bend the leads and leave glue on the leads.
16 x "104" capacitors installed
5 x "474" CAPACITORS
Now I mounted the 5 x "474" capacitors. The group close together at the top are the Tayloe detector filter capacitors to detect the IQ audio signals before the amplifiers.
5 x "474" capacitors
TAKE A BREAK - that's enough for now let's see if I can work some European FT8 non 40m... then carry on...
Was it a mistake to empty out all the components? Lots of searching for the right ones!!!
Tipped everything in a box of chocolates lid!!!
RESISTORS
PROBLEM
Got to section 3.30, "Install 2 x 36K resistors R32 & R33". There were two "orange-blue- black-red-brown" in the kit but when checked with a meter they were actually 39k! LTSpice re-simulation of the CW filter does not change much with the 39k resistors.
LTSpice with 39k resistors on third filter stage
Up to section 3.29 this is my build
Oh dear. I have found the batteries in my test meter were low, I have replaced them and now the 36k resistors read 36k. Have written to Hans to apologise.
Nearly made another resistor measurement goofy when checking the 750k resistor R35, it measured 560k until I realised I was measuring the resistance of my finger!!
WOW, that's all the resistors done. Here it is
Finished the main board resistors
OTHER COMPONENTS
Trimmer, electrolytics, transistors. Neat way the output power transistors are mounted and held down by a screw and washer, Very neat idea.
Output power transistors
Now for those wretched toroids. Two things will help. The first is the web site toroids.info. Here you will find the listed toroid core types T37-2 and T37-6 and for each the dimensions and more impportantly a way to calculate the inductance from the number of turns (or vice versa). And to the right length of the wire needed. This is great as you can cut a length of wire and not have to pull the whole length through each time, but just the shorter length you need. For example for L2 in the Low Pass Filter - 24 turns
T37-6 24 turns needs 35.6 cm of wire, cut 38 or so to be safe
Yep, its 24
So let's do all the coils 21, 24 and 21 turns
All the coils mounted
Next is the Antenna connector, a BNC type - though I would have referred an SMA to match all my other bits of gear.
FINISHED
Completed mainboard
NOW THE FRONT PANEL
Components mount on both sides of the front panel. First the front side resistors
Five front side resistors
Front
Back
The LCD is installed with mounting screw and nuts. One problem is that the righthand nut on the back cannot be fitted as it collides with the volume control, I temporarily loosened the volume control to get the nut on to have the correct spacing before soldering in the 16pin header. This remains a problem as it cannot be fitted again when the QCX+ is fitted in its enclosure.
Finished!!!
ALIGNMENT & ENCLOSURE
I have aligned the radio, there are two things to adjust, the input tuned circuit to peak on the 40m CW end of the band and the detector IQ phasing & balance to reject the wrong sideband - CW RX reception is on USB at 700Hz below the displayed TX frequency.
I have also purchased the excellent enclosure for the radio, and here it is before I put the top on. I did have a queer problem. When I tightened the nut on the BNC connector it pulled the main board backwards it disconnected the front panel, and the screen went dark - bit of a shock, but all was well when I removed the nut and pushed the two boards back together.
Finished radio
Second problem was crackling when the boxed unit was "tapped". This turned out to be poor solder joint on one of the LPF coils. It IS important to solder then on for the full 10sec to burn off the wire coating!!!
Now the challenge begins, to learn morse code!!! First a paddle morse key? I am building this one.
3D printed paddle morse key
1 comment:
Hello Antony
Many thanks for this post.
Happy new year with many projects.
I had already built a QCX 40m and now I am building a WB2CBA uSDX v1.02. A small QRP SSB / CW transceiver with interchangeable LPFs.
73 QRO
Gilles F1BFU
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