My radio is an mcHF kit that I just finished soldering up. It receives fine, but when I went to transmit it's giving off the scale SWR. I rechecked my antenna with my NanoVNA, and it shows 1.2 SWR at the same frequency. I would say there's a fault in my radio but when the radio is connected to a dummy load it shows 1.1 SWR. I'm going to retrace all the solder joints on the kit in case I've connected something wrong, but I thought I'd post here in case someone has hints on what to look for.

  • $\begingroup$ Did you calibrate your nanoVNA for the specific test ? If not, then that's your answer. $\endgroup$
    – wbg
    Jan 13 at 17:08
  • $\begingroup$ @wbg I calibrated the nanoVNA with the stimulus set to 12 - 16 MHz as my simple wire dipole is set to 14MHz. $\endgroup$
    – rcx935
    Jan 13 at 17:14
  • $\begingroup$ It is possible that the nanovna is not seeing problems with the antenna that only occur at higher power, but this is unlikely. Describing the antenna might help. $\endgroup$
    – user10489
    Jan 13 at 23:11
  • $\begingroup$ @user10489 that's possible. The antenna is a homebrew dipole wire with a 1:1 Balun in the middle. Very simple. $\endgroup$
    – rcx935
    Jan 15 at 7:32
  • $\begingroup$ What power are you putting into the antenna? Is it still an issue at your lowest power setting? $\endgroup$
    – user10489
    Jan 15 at 14:12

Perhaps your radio is way off-frequency, do you have any way to test that? A dummy load should be flat across a wide frequency range, so you get a nice low reading whatever frequency you TX at. But the antenna isn't, so if your radio and your NanoVNA are working at different frequencies, it would explain the drastically different readings.


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