QCX transceiver for 20M

11The QCX was built and working in a little over a day. Here is what I did

Just about to start!

Instructions for building are contained in a PDF file which can be found HERE

The parts supplied. The suggested build sequence is clearly laid out and easy to follow. With all kits I check the value of each component before placing it on the board for soldering. It is best to use the minimum amount of solder to make a good joint and trim off the wires protruding through the board after soldering. I use a pair of Lindstrom 7292 flush cutters which are expensive but I have never found anything to equal them. The first pair I had lasted 35+ years!

The SMD chips are mounted so no need to worry about soldering them in yourself. I recently purchased the PCB frame and it makes lifer very easy. They cost around £10 which is well worth it.

Following the instructions the DIL chips and the large socket were added first and then the capacitors followed by the diodes, crystals and resistors, pots, bigger caps, trimmers, headers and transistors. Then on the dreaded toroid winding. The 4 smaller ones were first and again I checked the value of each before fitting. They were spot on.

The instructions do say that winding the transformer T1 can be tricky. The number of turns on the primary are band dependent but full information is given. I downloaded all the information I could find and printed out a photo of the finished transformer.

Before soldering I used masking tape on the top of the toroid to hold the windings in position.

I then pulled through the tinned ends of the windings and soldered them after tinning them first! That is a crucial step, you must tin the wires or end up with a bad joint. Always check continuity of winding after soldering, it saves a lot of problems later.

The primary windings were then tidied up to be evenly spaced!

After assembly was complete the soldering was checked under an illuminated magnifier. It is a good idea to look carefully for any joints that need fixing and to remove any solder splash to avoid shorts. It is popular now to removed flux using white spirit and a cotton bud but do this carefully and do not saturate the board. If you use plastic cotton buds DO NOT put then in the bin as they can do damage to the marine environment. I keep mine in a bag and burn them. Yet to find a wooden version.

When power was applied it worked! Still needed to go through the setup procedure but it was straightforward.

Output power was measured at 2.5W which is much the same as other builders of the 20M version have reported. The first QSO was with an HA5 using a dipole strung across the landing! Really like this little rig. Have a case on order which will make it ideal for minimalist /P this summer.

What would l like to see? A multi band version!!!

Full information and ordering details at https://qrp-labs.com/qcx.html