I bought the (tr)uSDX as a kit from one of the recommended sellers and build it with the T2 mod (3:21, 0.4mm wire). When testing with 12V and 5V (USB) and a dummy load, the efficiency stays around 60% on all bands (80m, 60m, 40m, 30m, 20m).
What I tested so far (focusing on 80m):
1. Checking with NanoVNA and removing one turn from L52 (now 13 Turns, dip at 7.3MHz)
2. New T37-2 with 14 Turns for L52 (dip at 7.1MHz)
3. New FT37-43 for T1, but made no difference compared to 2.
I did some measurements while testing (U_supply = 12V, I_rx = 0.077A)
Code: Select all
Test | Freq | I_tx | Power | Efficiency | Vpp@Load | Eff (calc) |
------------------------------------------------------------------------
1 | 3.50MHz | 0.89A | 7.1W | 57% | | 73% |
| 3.65MHz | 0.65A | 5.4W | 61% | | 79% |
| 3.70MHz | 0.46A | 3.6W | 60% | | 78% |
------------------------------------------------------------------------
2 | 3.50MHz | 0.78A | 5.8W | 54% | | 69% |
| 3.65MHz | 0.54A | 4.4W | 62% | | 79% |
| 3.70MHz | 0.40A | 3.0W | 60% | | 77% |
------------------------------------------------------------------------
3 | 3.50MHz | 0.77A | 5.8W | 57% | 47.8V | 70% |
| 3.65MHz | 0.53A | 4.4W | 61% | 42.2V | 81% |
| 3.70MHz | 0.40A | 3.0W | 60% | 35.4V | 77% |
------------------------------------------------------------------------
| 7.00MHz | 0.40A | 3.0W | 58% | | 77% |
| 7.10MHz | 0.37A | 2.6W | 58% | | 74% |
| 7.20MHz | 0.35A | 2.4W | 55% | | 73% |
------------------------------------------------------------------------
Any suggestions what to check next? Rewind L51 or L15?
Thanks
Karsten
[EDIT]
After doing the calculation right, it seems much better.
Code: Select all
P_out
Efficiency = --------------------------
U_supply * (I_tx - I_rx)