I turned on my QMX without the USB cable with a dummy load. The sound was nice and quiet for more than 45 seconds but then the noise came on quite loud. I then connected it to my antenna (20m). Turned the QMX off and then on. Heard ft8 signals for almost a minute but noise came on loud enough to require turning down the volume (no ft8 signals anymore).?
Ron H
K7DQ?
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On Jan 12, 2025, at 1:03?AM, Chris via groups.io <chris.rowland@...> wrote:
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Your Tx sweeps look OK but your Rx sweeps show no Rx, nothing but noise.
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I'd check the inductors and transformers used by the Rx, the BPF and the trifilar transformer. Bad connections here could be the problem.
Another thing to try is to turn it on with no USB cable connected and listen to the FT8 signal.? Does it stop after 45 seconds?? If it doesn't that may be an indication that something is wrong in the USB cable region, although it's difficult to say RFI if you aren't transmitting.
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All speculation but may help,
Chris, G5CTH.
