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Hi Stan,

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Thanks for the tip.

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I did have a go at messing around with the band config for 20m but I was trying to get a plot similar to the examples rather than aiming to get a complete run.

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Could you share your band config please as a guide. I know that mine will be different..

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Cheers,

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Mel. M0KMD.

On Thu, Mar 27, 2025 at 08:34 AM, Mehmet Dinch wrote:

The plot doesnt look any better..

Try several different settings of either 'Frequency min.' and/or 'Frequency center'.? I was able to (with a few trials) get the plot to complete out to the full x-axis range.? I think that a 'complete table' is the issue for distorted audio, rather than the shape of the plot.? A couple of my band plots have very strange variations like that, but do not noticeably distort the audio since I got the plot to complete all the way across.

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See the more verbose message I just sent about this issue here: /g/QRPLabs/message/141884

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Stan KC7XE

On Fri, Mar 28, 2025 at 12:44 AM, Mehmet Dinch wrote:

Thanks for sharing your settings.

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Are these setting post calibration?

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If you are hardly getting any power out then the reason for distortion and only hearing peaks of voice is the dead zone Hans built into the QMX SSB in order to get the two-tone signal to pass through zero. Review the diagram at the bottom of the SSB beta page, just before the release info.

Gary

W9TD

On Thu, Mar 27, 2025 at 11:23 AM, Mehmet Dinch wrote:

The audio sounds like the QMX is only picking up the peak signals from my voice.

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Adjusting mic gain to about 70 seems to improve the audio. However, every time I key up,? there is now an awful lot of noise before I even start speaking. Once I start speaking the audio is ok'ish with a load of background noise.

Mehmet, the reason for this is described also on page QMX QMX_plus SSB settings (see Noise gate).

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73 Ludwig

Hello Mehmet and all,

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if you need significant more than 55 dB audio gain the micro is not sensitive enough for QMX use. You will find something about this on page QMX QMX_plus SSB settings from QRP Labs Wiki.

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73 Ludwig

Yeah, I just took a snippet of the 20m band. :-)

As I said, I can't judge whether that plot looks good or bad. Some of Hans's plots looked similar. Everyone's radio will likely have different looking plots as the hardware has variations.

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73, Dan - W2DLC

Your band configuration page looks very different from mine. I can see all of the bands at once.

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73, Dan - W2DLC

I forgot to add the band config screen.

Hi Daniel,

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Thanks for your suggestion.

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I have set the band edges and center frequency as recommended. The plot doesnt look any better..

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Mel. M0KMD.

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Mehmet,? I used the band configuration menus to move the band edges closer to the legal band edges, and then set the band center to 14.175.? Then set the mic levels carefully, then did calibration one page at a time using O. I managed to get nicer looking graphs that way. I'm not sure how to interpret them, but I also noticed PEP my output levels came up close to my tune levels at that point, and the audio seems to sound good.?

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73, Dan - W2DLC

Muhsin bey, selamlar :-)

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Thanks for the tip. I'm using the electret capsule removed from other hand mics or other scrap pcb's. No LED's on any of these.

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I wonder how significant it is that my plots are nothing like the examples in the documentation?

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Another interesting observation:-

I set my QMX back to factory default and dialed in what I found to be workable and tested with dummy load (without calibration).

With my antenna plugged in (20m dipole, monoband, good SWR 1.2), on TX, the audio was badly distorted again. I also noticed that there was hardly any power going out. The power meter needle didn't even move.

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Working through calibration again as I type this to try again...

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Saygilar ve hormetler.

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Mehmet (AKA Mel) M0KMD

Hi

strangely I had the same problem.
I was using a uhf/vhf handhelds mike.
after I found out that there was a LED connected inside the mike case
I took it out
now it is perfect
73 DE muhsin TA1MHS

I just found another mic capsule on an Arduino MAX9814 board. Took that off to try again.

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Without calibrated, much better audio! Adjusted mic gain and compression. I set the noise gate to 30 and everything else as default. Still not perfect but very much improved and very usable!

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Ran the calibration through and left every thing else as it was and the audio is very rough.

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I'm going to factory reset it again and dial in the setting I was happy with and leave it at that, unless anyone has any suggestions to improve calibration results to improve the audio.

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Note that there is a lot of merit in what Hans says. Not every electret mic are the same. This last one that I found on an Arduino board seems to work nicely.

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Cheers,

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Mel. M0KMD

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Hi Myles,

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Yep, I tried the dial back as well. I eventually settled on mic gain of 65 but the audio was still rough without background noise.

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Thanks for sharing your settings.

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Are these setting post calibration?

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Cheers,

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Mel. M0KMD.

Hans' suggestion of microphone can be found on the beta page: under the heading Microphone Choice.? Though I suspect this microphone is more sensitive than needed for HF radio transmission.

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I had a similar issue with the noise you describe when not speaking.? I found it was caused by having the Mic. gain set a little to high.? The sweet spot for me was to actually transmit silence and dial the gain down until that noise disappeared.

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My Mic. gain is set at 75, with Mic. compression set at 14, and Transmit EQ. Global gain set at -8.? Just for reference as all Mics. are different...

Hi Hans,

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Yep, that did cross my mind..

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In fact my first attempt was to use a PC gaming headset with mic. The audio gain was very low from the headset compared to the electret mic's I found in my junk box.

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These electrets seemed to work quite well on my PC. I would have thought they would work equally as well on the QMX...

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I forgot the mention, I also removed an electret mic from a Baofeng speaker mic to use on the QMX. That gave the same results as the other electret mic's.

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Could you remind me of the mic that you used please?

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Cheers.

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Mel. M0KMD