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: The USB connection is not working.
The QMX connects to the computer via USB using a virtual COM interface.
To do this, it needs a driver that is usually included in Windows.
In November I bought a computer (ACE Magican, Windows 11 Pro) that was missing this driver (usbser.sys).
No virtual COM interfaces could be set up, and the computer showed no reaction, when the QMX (and some other devices with this technology) was connected.
Pure USB devices worked.
After installing the driver, everything was OK.
Functional test:
Connect QMX to computer
Open device manager in Windows.
Turn on QMX. An entry with USB Serial Device (COMn) must open.
If not, there is some USB problem (virtualCOM driver or hardware computer/QMX)
73 Reiner
?
|
|
Re: The USB connection is not working.
On Tue, Jan 7, 2025 at 07:34 PM, Sean [AK6BM] wrote:
never been able to use straight c to c... I think it's missing a resistor to tell the computer to just treat it like a basic USB deviceThis was a problem with the early QMX boards, as you say missing resistors.? It was fixed in later QMX board versions and the QMX+ and by a number of people who fitted the resistors.? When you do that you can use USB C to C cables. ?
The OP says QMX+ so this isn't the problem for him.
?
Chris, G5CTH |
|
Re: PuTTY issue on Diagnostics screen
Did you hit enter when the initial blank screen appears?
Roger
8P6RX
Get
On 8 Jan 2025, at 05:17, "JohnD via " <gmail.com@groups.io target=_blank>[email protected]> wrote:
|
|
Re: PuTTY issue on Diagnostics screen
I can't get PuTTy to work when using the diagnostics screen on my newly built QMX+.
?
I've reloaded PuTTy twice, and I've reloaded v26 and v27 firmware as described above.?
?
When I go into the diagnostics screen PuTTy just locks up and nothing appears to work.?
?
Any advice would be greatly appreciated.
?
regards
John |
|
Re: [QMX] SMPS to linear regulator conversion tips
I used generic TO220 style linear regulators for my linear SMPS replacement, had to trim the tabs a bit but they are rated for 1A and while they get warm seem OK.
As Jerry says the ADC_* lines need to be a little high to keep the processor happy.? I added a 220k in parallel with the 22k resister on the high side or use 20k/22k for the potential divider. Or whatever you have to get a voltage that's a little high.
?
Running the 78M33 from the 5V line would reduce it's heat dissipation at the expense of increased dissipation in the 5V regulator.
?
Chris, G5CTH |
|
Re: Initializing:Enable SI5351A
It looks as if it failed initialising the Si5351, as the message says.? This is actually a MS5351M, IC204, does it look burnt or is it hot?
IC201, an EEPROM array uses the same I2C control so a failure there might show this error, is that burnt or hot?
?
If it's the MS5351 your mission, should you wish to accept it, is to replace it.
?
Chris, G5CTH |
|
Re: Computer not connecting to newly built QDX
I could not find it at Amazon. Perhaps it is discontinued. Thanks anyway. 73! de Bekir TA2RX 8 Oca 2025 ?ar 08:54 tarihinde Karl via <karlshumaker=[email protected]> ?unu yazd?:
|
|
Re: Best QMX AGC settings?
Hello Chuck Since there is absolutely nothing I can do to fix software Have you tried some of the settings people suggested in this forum??? ? OBTW, since some of the members of this group seem to be on I am not sure who you think is on the group who is on my team but I definitely assure you, no QRP Labs team (either? employees or less official) are active on this forum other than me.? 73 Hans G0UPL |
|
Re: Computer not connecting to newly built QDX
I made it from parts from Amazon. The prototype printed circuit board is just a bunch of through-plated solder pads to mount and connect every type of USB receptacle. It is powered by a 5 volt wall adapter but a rechargeable cell could be used. All the receptacles are on break-out boards so the connections were easy.
--
73 Karl KI4ZUQ |
|
Re: [QMX] SMPS to linear regulator conversion tips
Signals ADC_5V and ADC_3V3 back to the host should be a bit high by maybe a tenth of a volt.
If the processor doesn't see a high enough voltage,? it waits until it does before running any further code.
It's ok if those signals are a bit high, but there is no margin on the low side.
?
I'm amazed the 78M33 works at all, that's a lot of power to dissipate.
I'd recommend either going with a bigger regulator (and a heat sink), or feeding the 78M33 from your 5v linear..
?
Jerry, KE7ER
?
?
?
On Tue, Jan 7, 2025 at 06:32 PM, Adam wrote:
2. CPU needs two fake signals: ADC_5V (2.5 V) and ADC_3V3 (1.65 V). The |
|
Re: QMX and QDX - Not enough 5V PTT oomph
Donald, most MOSFETs have an internal diode, so the flywheel diode is not absolutely necessary for a small low-voltage relay.? If the relay has a large coil or runs off higher voltage, yes, I would definitely include the diode.
The very popular ATU100 tuner (7x7) has 14 relays with 14 FETs and just capacitors across the relay terminals, and I have not heard of any of those drivers blowing out (including in the one I have).
Stan |
|
Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
On Tue, Jan 7, 2025 at 06:48 PM, Adam wrote:
2. With one of BPF capacitors (C401, C402, C404) grounded on the IC402These two observations tell me that your problem is 'to the right' of the capacitor.? If it was 'to the left', i.e. towards schematic page 5, grounding the input side of the capacitor would also have made the problem go away.? If the buzz was coming through that capacitor, it could also be trapped on its input.? Grounding the selected one of those capacitors Have you checked carefully R401/R402/C406? A bad C406 in that biasing circuit could cause oscillations and disturb the audio.
Are you certain that there is no anomaly with T401?? Maybe one of the trifilar windings partially shorting against another one, due to enamel being scratched?
Is the buzzing only on 'left' or 'right' audio, or both? If it is on both, it is unlikely that the source is the op amps, since past their inputs, the paths are independent.? If it is on only one, I would suspect that op amp.
And finally, as unlikely as it seems, IC407 has been the most common failure source of anything related to audio in the QMX.? If none of the previous apply, I would replace that one.
Stan KC7XE
btw - you are the third person now recently who I have heard blew the IC403 with a strong overvoltage burning through the 5V supply, myself being one of them (I inadvertently turned QMX+ on with a 17.5V supply).? I don't know why the nearly identical IC402 didn't also blow.? Maybe it's the doubled bias across the Z/W pins. |
|
Re: QMX, one of op-amps self-oscillates at 25 MHz (or picks up the system clock?)
Chuck Harris via groups.io <cfharris@...> wrote:
On more than a few occasions I have found that a scopeBut sticking the probe didn't change anything in the audio. Wouldn't it do it, if this was the cause? Anyway, an update, if someone's still interested. After frying SMPS boards I decided to make linear regulators (which I generally wanted to do anyway) and I'm back to square one. QMX buzzes just like it did, but op-amp doesn't self-oscillate anymore. 5V line is clean too (with the SMPS it wasn't, there was some strange distorted waveform there, I can provide a photo if someone's interested; but the waveform is not there anymore and the symptom didn't go away, so it's probably irrelevant). Some observations: 1. With IC403 removed the buzzing stops (it only hisses, normal radio static noise). 2. With one of BPF capacitors (C401, C402, C404) grounded on the IC402 side, buzzing stops (only hiss / static noise is present), of course the capacitor that does this depends on the selected band. Probably because grounding it removes the biasing done by R401 + R402. 3. Grounding these capacitors on the other side (RX_IN) does nothing, the buzzing continues. I ordered two new LM4562 amps, I want to blindly replace them and test, but it's just that -- blind waving of the soldering gun with no real idea what can be going on. I have nine new 3253's (I had ten, but one replaced IC403 that developed a short after frying these SMPSes), but I don't want to replace IC402 just yet -- something tells me this chip is OK, I just see no reasons to suspect it, it's just a switch. Or are there reasons? Further down the line we have Q508 and all these PIN diodes and filters. Frankly speaking, I don't see anything here that could cause this buzzing. Should I try removing Q508, even if grounding its source made no difference? This is so tiny and fragile that I don't want to remove components without any suspicion. So, ideas are still welcome... Thanks. |
dl8lrz Reiner
Karl
to navigate to use esc to dismiss