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Hi all, can help me please, in Digi mode on any band my QMX is sensitive and I can hear CW chatter but in CW mode I hear very little on any band. I have removed and checked L407 and T401, both are correct. the RF sweep in Digi mode looks normal but in CW mode is way off where it should be. I have included a the RF sweep, can anyone tell me where to look next please?

Also dont think that it is related but when it was first built I had a faulty IC407 PCM1804 (loud clicking noises) I replaced it and it fixed that problem.

I don’t have my qmx at hand right now so I can’t validate, but I don’t think the sweeps care about whether it’s cw or digi mode? Also your attached cw sweep looks more like a sw bug. Maybe try a factory reset? Also I think 20M sweep might have a bug - the first time you do it you might get garbage results. You can try sweep on another band first then go back to 20M.?

73 de N6HAN Zhenxing

Probably you didn’t turn up the volume high enough in the cw mode?

Switching from Digi with a good audiolevel to CW brings a low audio. It's normal, please use the volume control.

73 Ludwig

I have facroty reset it, loaded a different firmware and turned the volume up - no different.

The RF sweep is different between digi and CW on all bands. Maybe if anyone explain where the signal goes for Digi and whete is goes for CW maybe that wiil give a clue,

Or does anyone have any idea for me?

Thanks

I just tested multiple times on my QMX. RF sweep results were not impacted by whether the mode was CW or Digi.

QMX is an SDR radio. My understanding is that the hardware signal path for CW vs Digi has no difference - they both go through the same LPF, same BPF, same QSD, same OP Amps, and same ADC. After A/D conversion and I/Q decoding, different DSP filters are used for different modes, but RF sweeps shouldn't be impacted.

If the RF sweeps were done right after factory reset and you still saw different results between CW/Digi, I'd say it's probably not caused by a QMX software/firmware bug.?If you have an oscilloscope and signal generator, you can trace the signals at those RX stages (LPF, BPF, QSD, OP Amps) to see if there's any discrepancies between CW and Digi mode.

BTW, have you flashed it with the latest firmware version?

73 DE Zhenxing

I had the same issue after upgrading to the version with AGC. I turned AGC on and could not hear anything on CW with volume turned all the way up. I turned AGC off and ?heard many CW signals on all (high) bands.?

Perhaps try one more factory reset. After installing firmware, the QMX will do a factory reset if the firmware requires it. But even so, I've found that I have to do another manual factory reset to get everything working as it should. Others on this forum have had to do the same thing, a 2nd factory reset. Hopefully that will resolve both Zhenxing's and Joe's issues? Fingers crossed for good luck! (that always helps too!).
--
73
de Roy - KI0ER
Littleton, Colorado USA

Ok I have found that if I do an RF sweep after a factory reset the results for CW look look correct,
if I then do a RF sweep on digi mode and then another on CW mode the CW mode sweep is all messed up, could this be a software issue?

On Mon, Apr 15, 2024 at 11:05 AM, <ivan@...> wrote:

could this be a software issue?

I think so. I had similar results. Sometimes rf sweeps are fine and sometimes not. It was changing without factory reset, only fiddling a bit around with the QMX.

73, Ludwig

Hi All
Hi band QMX.

I am wondering what Ive got wrong.

In digi mode I can hear quite a lot of CW. But if I switch to CW mode, I can find hardly anything other than the very loudest signal.

Any of the quieter CW that I could hear in Digi mode disappears, and yes Ive tried with AGC, and turning up the volume but still not finding those signals.

Any suggestions of where to look for the problem would be appreciated.
Plots for 20 mtrs attached in case something jumps out that I am just not seeing for looking!

Jon

On Wed, May 1, 2024 at 09:34 PM, Jon GM0HYY wrote:

In digi mode I can hear quite a lot of CW. But if I switch to CW mode, I can find hardly anything other than the very loudest signal.

Hi Jon, in digi mode the receiver bandwith is around 3400 Hz and in cw mode only 300 Hz. In digi mode you hear all the signals within these 3400 Hz but in cw mode only those within the 300 Hz fraction. Tuning the frequency you will hear other signals.

73 Ludwig

Hi Ludwig,

thanks for the reply.
yup I appreciate the huge bandwidth differance and its likely effect on the amount of "stuff" coming through. But
what I was experiencing seemed? to be something more than that.

For example? I could hear at least 3 or more? competing CW signals. One much louder than the rest but when
I switched to CW mode? I could only find the very loudest one, and I had to tune a a lot? further than I expected to to find that.
I could never find the others even with the volume way way up.

But tonight I updated to latest firmware and so do did a full factory reset and things seem much better than before.

I shall do further? testing tomorrow when I am less tired.

The real answer would be for me to build another one to compare it with :-)

73

Jon

I have fixed the radio, it now hears everything.

I had mis-wound T507

Instead of winding B to B and C to C I had wound B to C and C to B, A to A was correct and D to D was correct? (see the build document for T507 if this is not making sense)!!


All good now..