Kit: (tr)uSDX 5-band Multimode QRP by Up Tech Store on Aliexpress, purchased 2022-04-08 (batch 2). For details see DL2MAN.de.
Measurements
Supply voltage is 12V, RX current draw is 81mA.
The shunt setting was set to \(14m\Omega\), which gives the best match between reported and measured efficiency.
Efficiency and power as reported by (tr)uSDX, \(V_{pp}\) measured with an oscilloscope, the input current \(I\) was read off the bench power supply.
| Band | freq/kHz | Vpp/V | Eff./% | I/mA | P/W | P_true/W | Eff_true/% |
|---|---|---|---|---|---|---|---|
| 80 | 3560 | 44.8 | 57.8 | 828 | 5.50 | 5.01 | 56.1 |
| 60 | 5351 | 42.0 | 78.5 | 556 | 4.67 | 4.41 | 77.5 |
| 40 | 7030 | 38.4 | 77.2 | 476 | 3.70 | 3.69 | 78.0 |
| 30 | 10106 | 44.0 | 77.2 | 623 | 4.86 | 4.84 | 74.6 |
| 20 | 14060 | 42.4 | 76.3 | 584 | 4.13 | 4.49 | 74.6 |
Waveforms
- Yellow: \(V_{Drive}\), 1V/div
- Blue: \(V_{Drain}\), 10V/div
- Pink: \(V_{ant}\), 1V/div
80m
3560kHz, 56.1% eff
60m
5351kHz, 77.5% eff.
40m
7030kHz, 78.0% eff.
30m
10106kHz, 76.4% eff.
20m
14060kHz, 76.4% eff.
