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Target: QMX firmware 1_00_017 (second release)

Bug: QMX display and control and serial console frees when using VOL encoder when QMX is in menu.?

Reproduction steps: entering menu on QMX, select any item (for example CW Keyer). Then use serial console and go to diagnostics screens for testing the encoders/buttons, all work but when turning the VOL encoder, diagnostics screens stops working, also controls / display on QMX stop working (frees state).

Fix: Pressing Ctrl-Q in serial console, serial console jumps back to Hardware test menu menu and controls/display on QMX are working again. Leave menu on QMX and then diagnostics for VOL encoder doesn't frees (don't be in a QMX menu when using diagnostics).

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73 Lex PH2LB?

On 18/02/2024 16:06, Bryan Curl wrote:

one method from Maxwell jumped r27 to between r53 and r59.
another method jumped r27 to between c20 and pin 6 ic9b.
another to between c21 and pin1 ic9a.

Bryan,

The first is exactly what I suggested.
The other two are very similar but I do not know why the slight variations were made.

73 Alan G4ZFQ

Can anyone tell me if this is a bug....?

If I leave on the QMX all night long with WSPR running, there comes a time when it stops transmitting RF even though
the display still shows it transmitting the data, when the time comes!

I am using the GPS unit to keep the time accurate.

Repeat is set to "0".

Im interested in receiving wspr on my qcx+. I searched the topic and found 3 different mods , so not sure of the best one for my needs.?

one method from Maxwell jumped r27 to between r53 and r59.

another method jumped r27 to between c20 and pin 6 ic9b.

another to between c21 and pin1 ic9a.

I dont think the one for the original qcx makes sense for the qcx+. but not sure what the difference between the other two would be.I would be installing a switch.

before unsoldering anything and fooling around any help understanding these differences would? greatly appreciated.
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regards,
Bryan, N0LUF

On 18/02/2024 13:52, John Kirby wrote:

only a couple hundred Hz wide abd centered at 700 Hz, so only a small number of WSPR stations can be seen/heard at one time

John,

The entire WSPR segment is only 200Hz wide.
The decoder centre frequency is fixed at 1500Hz.

The only easy way to decode is to send 1400-1600Hz to the decoder.
The QCX filter centre of 700Hz makes 1400-1600Hz very weak.

73 Alan G4ZFQ

How to receive WSPR via an unmodified CW receiver

I do not own the QCX Mini but do own several QXC

1) The many/many (several dozen or more) stations I see/hear (at the same time) on a true SSB (Not in CW mode) receiver make up a single as in only *ONE* SSB VOICE station (from apx 300 to 2500 Hz)

2) the QCX CW filter is very/very narrow and only a couple hundred Hz wide abd centered at 700 Hz, so only a small number of WSPR stations can be seen/heard at one time

3) tuning the VFO up or down a couple hundred Hz will receive the next group of WSPR stations

4) WSPR is transmitted USB (Upper Side Band)

5) the QCX will do both USB and LSB and only decode 100% in USB mode... I goto MENU and switch between "CW"? and "CW-R" to change from USB/LSB? ($$ and can only assume the Mini does the same $$ :>)

6) AND the PC clock must be set to WWV? +/-? rwo (2) seconds or better

Hope this helps to understand some WSPR decoding problems

72 73
John
N3AAZ

Did you switch off the QMX or the power supply?
Could you check the voltage from your power supply during a switch on and off using a oscilloscope and a resistor as a replacement of the QMX?
Switch in a first test the load and in a next test the supply.
In a next step if all was ok you could use your low band QMX as a load.
Did you read ?

Thank you. I just blew out the votive candle I had lit since finishing my kit!
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72/73 de Steve, K9NUD

Jim,

I think over time as others experiment with the AGC settings there will be plenty of examples of settings that will fit into those categories.? As an owner of an Elecraft K3 and K4, both of which have a similar range of AGC settings, I found that it's great to have that much flexibility in shaping your rig to what you prefer.? It didn't take long for examples of AGC settings that worked best for DX, ragchew, noisy enviroments, etc to be posted on the Elecraft boards. Beats the heck out of the lack of such flexibility with the "Big 3" manufacturers.

73, Bill NZ0T

AGC is really nice addition! Been playing with the settings - here are my current ones:
Thresh 9
Slope? 40
Noise? 10
Hang? ?30
Smooth 50
Recovery 40
Blocks? 4
S9? ? ? ? ?9
AGC? ? ?ON
dB/Bar? 6

Can't wait to take it on an outing!
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73, Dan? NM3A

Wow, superb, thanks Hans.

73 Simon
G0FCU.

Final installment…

Today I finished up this QMX. ?T501 and T507 didn’t look right to me. ?Fortunately the PC board pads seemed to be in great shape. ?I removed each transformer, rewound then and soldered them in.

? T501 looked as if too much heat had been applied when soldering it in. ?The enamel had melted and I suspected shorts. ?

T507 looked like the primary and secondary could short easily since too much enamel had been removed. ?Maybe I could have put some kind of adhesive to stabilize it. ?But rewinding it seemed the better approach. ?I always use green wire for the 10 turn portion and red wire for the single piece. ?Looks great that way.

Anyway, the big moment of truth. ?Would everything else work? ?After all there was 5.9v on the VCC rail. ?I know the AD converter is especially sensitive. ?I powered it up at 7v and ran through the audio, Rf and image tests. ?All very good. ?The audio output was even very good in the headphones. ?I powered down. ?That worked too.

i then adjusted my power supply to 12v and powered on for TX testing. ?I got 4 to 6 watts out across all the low bands. ?Very good. ?I’m getting better and better with each RWTST transformer that I wind. ?Hi hi.

Then I remembered that Hans released rev 17 last night. ?I didn’t see any show stopper bugs posted. ?So I loaded up rev 17. ?Went through all the tests again. ?Super! ?Love the AGC! ?Thank you Hans.

The final step is putting it in the case, inspecting for clearances and shorts and one final test on the air. ? That went very smooth. ?A very rewarding project.

the post office had closed for the day. ?This will ship out to its owner first thing next week.

By the way, I’m trying to get an OBS system working on Ubuntu with video so I can record some of these adventures. ?That has given me more trouble than I anticipated so far. ?But I’ll get it - soon I hope.

73
Jeff
W1NC

On 17/02/2024 14:23, Karl Haas via groups.io wrote:

Thanks, Alan. I'll have a look at the schematic.? That sounds promising.

Karl,

Mine is a v1 QCX. I disconnected the end of C20 that goes to IC9b.
Connected that to the centre pole of a 2-way switch. One pole back to C19, the other pole to to R27 slider.
This bypasses the audio filter.
I have not looked to see how that could be done with a mini.
.
Note there is a permanent modification to the audio filter mentioned on the website.

73 Alan G4ZFQ

Hans,

As always I am looking forward to hearing you speak at FDIM. You probably already have planned your talk but if not I would like to suggest it include an explanation of how the SSB implementation in the QMX will actually work. What are the underlying principles of how SSB willl be generated and what are your expectations of how well that can work given the available compute power? Thanks.

Jim AJ8S

Hans,

The new AGC is working great on my QMX. It was nice that you explained how it works and gave us access to all the parameters. Once things settle down, I suggest it would be better to simplify it. My suggestion is that there would be only a slow / medium / fast release setting and the equivalent of a high / medium / low "RF gain" setting. Hang could be just on / off. It would be nice if these were accessible from the radio menus.

Thanks gain, AGC is a huge improvement making it a great little radio!

Jim AJ8S

The repair appears to have been successful, including adding an SMT diode near Q508.

Photos available at:

Compton, did you ever figure this out?

On Sat, Feb 17, 2024 at 07:58 PM, Hans Summers wrote:

Yes, you are correct. But this is also how I have declared that the system works. If you look in the operating manual section on the AGC I described all the stages the signal goes through from the antenna BNC port through to the 3.5mm earphone output. You'll see that I said the band configuration gain value comes before the AGC action. The audio attenuator and volume control gain come later. This is why they don't affect the S-meter. So the intention was that the band configuration gain can be used to equalize and calibrate, to cancel out any differences in BPF attenuation etc between the bands.?

?

On my unit a band configuration gain of 54 on 40m calibrates the S-meter correctly. Note that the S-meter is logarithmic with 6dB/bar. This doesn't depend on anything in band configuration, it's linearity as 6dB/bar is always accurate. But the number of bars for a given level such as S9 would vary and that's what needs calibration by adjusting the gain in the band configuration screen.

Thanks, it's clear to me now. I read the AGC section in the manual (very nice, btw) but I was under the (wrong) impression that the system somehow would compensate for the audio gain setting in order to keep the calibration. Reading you post, I think you have a good point, with a sig. gen. one can manually set gain per band and end up with a nice S-meter all across, unlike some top brands which shall remain unamed :-)

So thanks again for lifting the fog :-)

Regards,
YO3GFH
op. Adrian