开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. QRPLabs
  2. Topics

Noise around 150Hz on digi mode with my #qmx

 

Hi,

I build my QMX 1 week ago. The process run well and I'm able to use it.

However, I got some weird noise around 150Hz on WSJTX, as you can see in my screenshot. I trying both magnetic loop antenna and dummy load. It don't know were to search to find the reason on the noise. I tried a 9V battery and a USB-C PD set on 9V as power source but I still have the noise. I try with both ACG/VOX enabled/disabled.

I ran the sweep hardware test using the terminal access and all curve sounds good, according to the operator manual. I also verify my band settings on the menu and all correctly setup too.

Do you have any clue what can be the cause of that RX noise?

Thanks,
VA2HSW/F4HSW
 

Hi Quentin

This is a WSJT-X feature called "Flatten", which is intended to compensate for the imperfect passband of some crystal filters etc (with suitable calibration). On QMX the passband is already flat, it's a DSP filter and very flat. You need to switch off "Flatten". It's a checkbox at the bottom of the waterfall display screen of WSJT-X.

73 Hans G0UPL


On Sun, Feb 25, 2024, 9:14?AM Quentin VA4HSW/F4HSW via <qrp.le8b2=[email protected]> wrote:
Hi,

I build my QMX 1 week ago. The process run well and I'm able to use it.

However, I got some weird noise around 150Hz on WSJTX, as you can see in my screenshot. I trying both magnetic loop antenna and dummy load. It don't know were to search to find the reason on the noise. I tried a 9V battery and a USB-C PD set on 9V as power source but I still have the noise. I try with both ACG/VOX enabled/disabled.

I ran the sweep hardware test using the terminal access and all curve sounds good, according to the operator manual. I also verify my band settings on the menu and all correctly setup too.

Do you have any clue what can be the cause of that RX noise?

Thanks,
VA2HSW/F4HSW
 

Hi Hans,

?

Thanks a lot, I ignore that feature exists on WSJTX.

?

73,
Quentin VA2HSW/F4HSW

1 - 3 of 3