Categories
Gear Kits

A QMX Build in Pictures

Hans Summers’s QRP Labs transceivers are incredible pieces of equipment. I’ve built several and below details my build of his newest offering: the QMX for 20 through 10 meters. I won’t reiterate all the details of the radio which you can find on his website. Instead, I’ll offer all the photos and limited commentary of my build process, spanning six sessions and twelve hours.

All the Bits

Installing the Discrete Components

There’s not a lot of room to work, but by being careful, all will be well.
Round One: Capacitors
Round Two: Diodes
Round Three: Inductors
I did my best to keep the components vertical but this was tough at times due to the lack of space.
Round Four: Transistors
Transistors bolted down

Winding the Toroids

I’ve never wound a binocular toroid before.
It was highly satisfiying to have the finished product.
Winding the trifilar toroid wires together tightly.
As you can see, I “phased” my wires with tape before twisting them and winding them around.
As an (apprentice) electrician, I help pull in three phase conductors all the time.
Frequently, the insulation is all the same black color.
To make sure we are connecting the phases correctly, we tape the conductors at both ends before we pull them into the conduit.
Doing it this way eliminates the hassle of using the multimeter to ring them out.
Once soldered to the board, I double checked the phasing for extra peace of mind.
The phase tape method worked out fine.
All toroids in their right place

Installing the Headers and Connectors

All connection jacks installed.
Power board header pins installed. At this point, the main board was complete.

Building the Screen and Buttons

Save your component lead scraps.
I had to desolder this rotary encoder as I had a pin shorted to ground, my only soldering error of the build.
I’m glad I found this mistake before I had it all buttoned up.
It pays to check your work as you go.

Checking the Enclosure Alignment

Good, and ….
… Good! All well aligned!

Applying Power

Voltage and current limited to Hans’s recommenations.
With voltage applied, no current draw while off. A good sign!
Here it is in straight key mode, putting out around 5W on 15 meters with 11V of battery supply.
I’ve only made one contact with it (into Mexico!), but the Reverse Beacon Network tells me that it works on all bands.

While a non-traditional post of sorts, I hope that you enjoyed looking through the photos and you are inspired to build one of your own. It was an enjoyable experience and I’m glad that I found enough time to get it done. My thanks to Hans and the QRPLabs team for providing all of us amateurs with wonderful kits.

2 replies on “A QMX Build in Pictures”

Good job, Don! I put in many years as a journeyman electrician…..mostly shipyard ship building and industrial electrical/electronics. Great trade!!!

Walter, K5EST ⚓ ZUT ---> CW Forever

Like

Leave a comment