(tr)uSDX Forum

Posted: **17 Mar 2023, 22:23**

Hi,

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%        |
------------------------------------------------------------------------

The power and efficiency values seem valid. 3.50MHz output power a 1. maybe a bit to high. Squeezing turns of L51 makes not a big difference.

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)

To fix the displayed value, you need to adjust R Shunt in the Menu.

Posted: **17 Mar 2023, 22:44**

Hallo OM Karsten,

I think you forgot to substract 80mA from your supply current....

73 de Chris

Posted: **17 Mar 2023, 23:26**

Hello OM Chris,

you are right, I had some calculation errors there. I added the calculated values to my first post, so now it does not look to bad.

Thanks for the hint,
Karsten

(tr)uSDX Forum

Efficiency at 60% on all bands

Efficiency at 60% on all bands

Re: Efficiency at 60% on all bands

Re: Efficiency at 60% on all bands