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On 07/01/2025 06:01, hanz YL3JD via groups.io wrote:

The USB was complaining that the port was asking too much power so Mac M2 stopped the port.

Hanz,

This should not happen.
The USB 5 volts is not connected to a QMX.

Check the USB cable. Make sure the 5 volt connection is not shorted to ground.
Check the cable alone. Then with it plugged in.

Ensure that there is no splash of solder on the QMX USB socket connection.


73 Alan G4ZFQ

Hello,

I just built the 10/12/15/17/20m version of the QRP Labs QDX digital transceiver (revision 5). I used the QRP Labs QDX website manuals and watched a multitude of YouTube build videos before and during my build. The inventory, component placement, soldering, and testing went well. I used a 5x desk mounted magnifying glass, 40w Weller conical tip soldering iron, liquid flux, and 62/36/2 solder.

Unfortunately, the RF Sweep result for my 20m band doesn't look right. The operating manual indicates that the RF Sweep should display a peak at the band marker. Unfortunately, my RF Sweep shows a flat spot for most of 20m. I looked through the QRP Labs QDX trouble-shooting page, re-tested the test points for L12 (page 27 in the build manual) and everything tested good. I decided to apply my soldering iron to the L12, L6, and L2 soldering pads for 15 seconds each to make sure that any remaining enamel would be burned off (if any existed). After which, I ran the RF Sweep again. Although my output changed a tiny bit, it doesn't look anything like what's depicted in the manual.

I'm not really sure what to do at this point. I've counted and recounted the number of turns on L12, L2 and L6; they look correct to me. I was SUPER careful when soldering, there are no burns or other soldering mishaps on the board. I'd really appreciate any help the community could provide.

Cordially,

Rob, AH6X

P.S. - I converted this post to a webpage to make it easier to look through.

Supplied wire on recent kit batches is all 0.33mm and this provides the highest performance (older
kits use 0.60mm wire)

?

Dan,

I am a retired EE, and easily 50 years a ham. I know
about band conditions, have experienced a lot of different
receivers, and through the conscientious use of PPE, have
ears that still work properly.

I spent most of my career designing hardware and software
for embedded systems, and in the course of so doing, wrote
tons and tons of "C" and assembler code.

I "get" the signal path of SDR's, and I don't think my situation
has anything to do with hardware, or my ears.

What we are talking about, is 40m on a day when the ambient
noise level was 1 to 1.5 bars, when something happened that
caused every signal on the band to have its audio tone hard
clipped by what sounded like random noise.

Initially, I thought it was some overdriven CW transmitters...
But it was way too many.

This situation only happened when the AGC was turned on, and
only in CW mode. Everything was clean and pure in the USB DIGI
mode.

I was using the factory default AGC settings, and I think
the latest release of software.

That sounds like an AGC issue to me, and there is no AGC
hardware in this radio, at all, so a software AGC problem.

I don't believe that my radio, or my situation is unique,
so, perhaps my report will trigger someone to actually look
for, and apply a fix.

Since there is absolutely nothing I can do to fix software
problems in my radio, I am hoping for band-aid solutions in
the AGC settings section.

Thus far, the only thing that seems to help is to all but
disable the AGC by putting the threshold up to 12. That seems
quite counter to those suggesting settings of 3 or 4, which
caused me to ask: for what band?

OBTW, since some of the members of this group seem to be on
Hans' team, would it be too much to ask that they identify
themselves as such somehow in their posts?

-Chuck Harris, WA3UQV

On Mon, 06 Jan 2025 08:30:26 -0800 "Daniel Conklin via groups.io"
<danconklin2@...> wrote:

Chuck,
Regardless of software definition or not, the hardware will have
variations, and your ears will have variations, and band conditions
will vary. Your AGC will respond to those variables digitally but
converted to an analog way because ultimately, the output is analog
to your ears. I have one ear that's a lot more sensitive than the
other. Certain loud sounds can get buzzy and distorted to that ear.
The other ear has had damage due to unprotected exposure to very loud
sounds over time, so certain parts of the audio spectrum are muted.
The interaction between the CW filters and the AGC settings can
compensate for some of that, but not all of it. Part of the reason
for the default settings was to help compensate for a thumping sound
some were getting when keying.? I never even perceived that thump
with either of my QMXs. I don't think I have that thump because it's
not there in either ear. You are having with some pulsing at low
levels. I haven't noticed that in any situation I've
experienced...yet. Maybe I will, now that you've called my attention
to it. Also, remember that Hans made you check a box stating you
understand this is Beta software, so you knew what you were getting
into. I know he makes a note of every complaint, and has it in mind
as he works on the firmware, so he will probably try to reproduce
your observation eventually. Anyway, I'm happy with my settings which
most of the time are:

Threshold S: 8
Slope dB per dB: 65
Noise Filter: 9
Hang time: 55
Smooth samples: 60
Recovery dB/s: 8
Sample Blocks: 2
S9 sounds like: S9
AGC Display: On
AGC dB per Bar: 3

But, I'm also still experimenting.
--
73, Dan - W2DLC

Yes. the bottom.
Ed
AB8DF