Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- QRPLabs
- Messages
Search
|
Re: #qmx SSB Firmware beta 1_01_004 release
#qmx
Hello Chris If the calibration didn't go well, please use it without phase pre-distortion. It's still very good even without phase pre-distortion. I showed examples here: Scroll down to the section headed "2-tone test measurement results" all of which are done at the standard 700 / 1900 Hz tones. You can see that the pre-distortion makes an improvement but even when off, the IMD is still very respecrable. Bear in mind that two tone testing is a particularly harsh test for an SSB transceiver. In the case of polar modulation specifically, the results get better at narrower tone spacing (and conversely worse at wider tone spacing). As soon as I can, I'll get to investigating how the calibration could be made more robust. I believe apart from this issue there aren't any major problems with the SSB firmware now.? 73 Hans G0UPL On Thu, Apr 17, 2025, 22:30 Chris KB1NLW via <chrisrey1=[email protected]> wrote:
|
|
Re: #qmx SSB Firmware beta 1_01_004 release
#qmx
It was not meant to be nice or funny, but to be a question to Hans since many people who have tried this beta version cannot perform complete SSB calibration.? I spent many hours unsuccessfully trying to calibrate four QMXs.? Hopefully Hans, who I greatly admire, is making progress.
My apologies to anyone who misinterpreted my intentions.? |
|
Re: New Chat: QMX weird behavior
#chat-notice
Most likely ESD, static discharge.? touch something else first see if it goes away.
?
Could also be bad soldering.
?
--
Allison ------------------ Post online only,? direct email will go to a bit bucket. |
|
Re: QMX Blown Finals. Will a DC-DC Adjustable Buck Converter prevent future failures?
Anker banks are good; and it's worth noting for any future folks reading this thread that you can?get 12V PD USB-C cables, but they work with fewer banks and adapters. Notably, no recent Anker AC plug or powerbank supports 12V output.? Also, many larger powerbanks/"solar generators" now have 12V DC output plugs. Always test them! I've measured many that will happily drift all the way up to 13.7v. I use a Drok buck/boost converter on the 12v output of a Anker Solix bank and have gotten consistent 12V into my QMX+ that way. 73! --?
On Thursday, April 17th, 2025 at 9:30 AM, Stan Dye via groups.io <standye@...> wrote:
|
|
Re: PA mod for QMX+
Parasitic capacitance to ground of the PCB-traces at the filter input and output (50pF? 100pF?).
~10pF for each 1N4007 "PIN"-diode. Series inductance of T501 and T507. Shunt inductance of T507. Filter tuning is practically only possible if it is done directly on the QMX+ PCB Gottfried |
|
Re: PA mod for QMX+
Measure the filter in-situ in the QMX+, and I think you'll find a droop in the filter passband.? (I see such a droop on more than one of my QMX+ filters).? There is some parasitic interaction going on, and I don't know what it is.
You can do the measurements with a vna or tracking generator or noise source sending the signal in at the input switching diode cathode, and measuring at the output BNC or at the LPF output switching diode (the two places will give somewhat different results).
?
Stan KC7XE |
|
Re: New Chat: QMX weird behavior
#chat-notice
Check the soldering on the volume encoder pot. I added a small wire between the board and pins to be sure of a positive connection. Mike Krieger On Thu, Apr 17, 2025 at 12:22?PM Group Notification <[email protected]> wrote:
|
|
Re: QMX Blown Finals. Will a DC-DC Adjustable Buck Converter prevent future failures?
I wired my first QMX for 9V, and have been very happy that I did.
I also use a PD power bank and 9V trigger cable for it, and it has worked very well.? The powerbank measures right at 9.0V, but at transmit there is about a .2V drop in the cable, so I am always transmitting at about 8.8V, which is a fine safety margin, even for FT8.? Note that because of the steeper voltage curve for a 9V build, you don't need to reduce the voltage as much for the same margin.
And the power bank I chose is an Anker 10000mAh unit that is smaller than the QMX - a perfect match, which gives me several hours of operation.
Stan KC7XE |
|
New Chat: QMX weird behavior
#chat-notice
Group Notification
A new chat has been created: All,
?
I've built the QMX rev 4 60-15m transceiver.? ?I've ran all the terminal test and analysis sweep with positive results.? ? I've even made an FT8 contact on 15m, and CW contact on 20m.? ?However, the radio has had a behavior repeated multiple times that I don't know where to start to investigate.
?
When I reach over to adjust a knob, push a button, or simply touch the case, the radio's screen will loose all characters, and audio will go to a loud hiss.? Powering off and then on resolves the issue.? ?The issue has repeated itself possible 8 to 10 times over the past ~10 hours of on time.
?
Any ideas on what might be causing the issue, and/or how to resolve.
?
Regards,
Wilson Little (NT5AT)
?
?
?
By: NT5AT - Wilson <wilsonlittle66@...> Do not reply to this message to post to the chat. You can participate in chats only through the group's website. |
|
Re: QMX+ with ~1000 tone on 12M & 6M
Mine happens only when LSB is selected on the upper bands. On some bands it¡¯s louder. If I switch to USB, CW or Digi I don¡¯t hear it. On 160 to 20 meters it¡¯s not there. I also notice it will increase in volume then decrease. It will also be there one second then be gone and then come right back.
It frustrating. It sounds like it could be processor or logic related the way it turns on and off.
The up side is that LSB isn¡¯t used for the most part on the upper bands.? I would love to resolve this. I don¡¯t see any obvious problems on the board.?
Don. |
|
Re: QMX T501 wire gauge
Yes you can Paul On Thu, Apr 17, 2025 at 08:27 Paul Egan via <paulegan789=[email protected]> wrote:
|
|
Re: QMX Blown Finals. Will a DC-DC Adjustable Buck Converter prevent future failures?
Paul - rewinding for 9v operation is certainly an option - I've built 2 QMX, one for 9v and the other for 12v, and I still am undecided which is more convenient.
toggle quoted message
Show quoted text
OTOH, you could just buy a cheap PD powerbank with a 9v trigger cable and run whut ya brung on the digi modes. vy 72 de Russ, va3rr On Thu, Apr 17, 2025 at 10:38 AM, Paul Egan wrote:
I'm thinking I may rewind T501 to make it a 9V rig. Then use the Drok |
Ronald Taylor
va3rr
to navigate to use esc to dismiss