My just finished QMX+ by QRP Labs is a 11 band multi-mode transceiver that I built from their kit. Full details here. Pictured below is the result of the “smoke test.” Success on first power up!
Some time ago, I built the little brother, the more compact QMX successfully from a kit. That 5 band version has been delightful in practice, but didn’t have all my choices of bands. It was the “high band” version with 20m-10m. I wanted to add at least 40M. The QMX+ offers that and more. So, after the smoke test failed to produce smoke, it was time to adjust the display (tone down those boxes) and try 40m. Contacts from my Central Florida home to Indiana and Rhode Island happened in the first 10 minutes. Later in the day, after 20m opened, I made contacts in CA, CT and elsewhere.
Next, was walking through the myriad of settings. Most of all, I tweaked the CW Filters and AGC to my liking. A couple of days into using it, I’m very pleased. It seems a bit more sensitive than its predecessor in that I’m more easily hearing stations in CA and OR. This radio is capable of some DiGi modes, operating as a WSPR beacon, and newly available SSB. My own interest is strictly CW, so I have no comments about the other modes.
For anyone considering building these kits, I’ll suggest some soldering experience to start. The radios are somewhat difficult because of parts size (small) and density (very). The QMX is more challenging than the QMX+ because of multiple layers in a small case. The QMX+ uses a single larger board in a larger case.
Careful work, with no rush, worked well for me. ABSOLUTELY REQUIRED is careful inspection of every joint with a jeweler’s loupe. Smoke usually is the result of unwanted solder bridges. Use the loupe!
For the record, here are power measurements that I have for this radio.
| Band | Freq (MHz) | Watts |
| 160m | 1.838 | 5.81 |
| 80m | 3.573 | 5.16 |
| 60m | 5.358 | 4.62 |
| 40m | 7.074 | 4.25 |
| 30m | 10.136 | 5.19 |
| 20m | 14.037 | 3.88 |
| 17m | 18.104 | 2.83 |
| 15m | 21.094 | 4.82 |
| 12m | 24.924 | 3.20 |
| 10m | 28.124 | 4.57 |
| 6m | 50.313 | 3.25 |
This power distribution looks very similar to others in the QRP Labs series of transceivers. Yes, I would like 20m to be a bit better and might mess with the filter torroids to see if I can bump that a bit. Yet, as it is, I don’t think there’s much difference between 3.9 watts and 5 watts. The little brother QMX has reached Alaska and mid-Germany from central Florida with very similar power figures.
