Re: #qdx QDX and a smoked BS170
#qdx
James, one more thing...
The event that took out your BS170 may have reached all the way back into the clock generator chip. If you find that the fault is on the 3v3 rail, there is a good chance that it is at the clock generator.
JZ
James, ouch!, that sounds pretty grim! Recall that the 3v3 regulator runs off of the 5v0 rail so in a sense everything runs off of 5 volts and the short could be anywhere. Removing IC1 may help the isolation process.
With a 900 mA current draw, something on that board is probably getting quite hot.? Finger testing the chips might give you an idea where the fault is. Better yet, use an IR camera if you can put your hands on one.
Good luck JZ KJ4A?
I'd like to add a little more info from the troubleshooting I've just completed.
IC5 is still removed.
With IC2 removed, current draw = 0ma. -- I trust this means that my issue lies with something on the 5v rail?
IC2 removed and powered by itself is drawing about 3ma and putting out 5v.?
Q7 removed = 0ma.
Q7 removed and bypassed = 900ma
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Re: #qdx QDX and a smoked BS170
#qdx
James, ouch!, that sounds pretty grim! Recall that the 3v3 regulator runs off of the 5v0 rail so in a sense everything runs off of 5 volts and the short could be anywhere. Removing IC1 may help the isolation process.
With a 900 mA current draw, something on that board is probably getting quite hot.? Finger testing the chips might give you an idea where the fault is. Better yet, use an IR camera if you can put your hands on one.
Good luck JZ KJ4A?
I'd like to add a little more info from the troubleshooting I've just completed.
IC5 is still removed.
With IC2 removed, current draw = 0ma. -- I trust this means that my issue lies with something on the 5v rail?
IC2 removed and powered by itself is drawing about 3ma and putting out 5v.?
Q7 removed = 0ma.
Q7 removed and bypassed = 900ma
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Re: #qdx QDX and a smoked BS170
#qdx
I'd like to add a little more info from the troubleshooting I've just completed.
IC5 is still removed.
With IC2 removed, current draw = 0ma. -- I trust this means that my issue lies with something on the 5v rail?
IC2 removed and powered by itself is drawing about 3ma and putting out 5v.?
Q7 removed = 0ma.
Q7 removed and bypassed = 900ma
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In my clock kit manual, Hans says to use a clean well regulated power source. I grabbed a 5v switcher from the collection and since it was running 5v with or without the load I went with it.
Sense I just bought an Oscope I decided to learn how to measure ripple, etc, and learned that I had a better option in the junk box with a linear supply. But I dont know what the characterization of a "clean" power source is, what consequences result from a dirty supply are and so on. How clean does the clock supply need to be?
My Meanwell lrs-150-12 and -24 are rated at 150-156mv p-p at 20mhz with 12 inch twisted pair terminated with 47uf and 0.1uf caps.
Is this considered clean enough for the clock and qcx, 50w amp rigs? It seems to be. My 5V wall wart measures better that this on the scope with a similar setup.
--
regards,
Bryan, N0LUF
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Re: QDX SWR protection circuit?
#qdx
I have a project at work where I needed to simply convey a bunch of machine states. I was amazed at how much information I can share with a 3 color LED. With color and solid and blink I can easily do 20 states. My boss is yellow blue colorblind and my coworker is red green colorblind so that limited the colors I could use.?
Colin ? ? ? ? ??  ? ? ? ?K6JTH
On Sun, Feb 25, 2024 at 8:34?AM Alan G4ZFQ < alan4alan@...> wrote: On 25/02/2024 15:57, Mike KK7ER wrote:
> I doubt Hans has time or motivation to make any big changes to the QDX
As you say it is a BIG change. Requiring new PCB to take the extra
components and processor connections. Maybe a LED to show it has activated.
The QMX is slowly progressing, then the QSX...
73 Alan G4ZFQ
--
Colin - K6JTH?
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Re: QDX SWR protection circuit?
#qdx
On 25/02/2024 15:57, Mike KK7ER wrote: I doubt Hans has time or motivation to make any big changes to the QDX As you say it is a BIG change. Requiring new PCB to take the extra components and processor connections. Maybe a LED to show it has activated. The QMX is slowly progressing, then the QSX... 73 Alan G4ZFQ
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On 25/02/2024 15:34, LA1KHA Kjell wrote: would like to have a mod to run qcx transiever on 100mW low and 1W high Kjell, I would try using a lower voltage, maybe a QCX would work as low as 7.5 volts. Separating the PA power feed would enable lower voltage, lower power out. 73 Alan G4ZFQ
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Re: QDX SWR protection circuit?
#qdx
We're talking about potential new QDX features.?
But at this point the QMX features are a superset of the QDX features.
Realistically, I doubt Hans has time or motivation to make any big changes to the QDX design when customers can just buy a QMX.?
The only difference I can think of at the moment is that the QDX is always powered on while the QMX requires a button push.?
IIRC, there was a thread here on remotely turning on the QMX.?
That may be all that is needed to swap out a QDX for a QMX.?
73, Mike KK7ER?
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Although the USB 3.x standard states "any device" may not draw more that 500 mA, there are "charging standards that allow current draw up to 1,500 mA.? Many laptops and other devices have dedicated USB charging ports.? "Most" will allow the high current on the normal USB port
Keep in mind that this works best when you are using a single high current draw device, and any other device on that "hub" is not drawing more than (say) 50 mA.? I do "in vehicle testing".? We have tested devices similar to what Howard showed on a couple of Lenovo and Dell laptops.? In some cases, we had issues with charging the battery during the process and some ground look issues with our other equipment connected to the same laptop.
-------
Rob KB8RCO
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Any tryed to mod the qcxmini for lower power and better battery life.
I like to run QRPp wirh a PP3 9v battery on a Rockmite with power 100mW, but would like to have a mod to run qcx transiever on 100mW low and 1W high.? Would like to have any tip .Posible it can use the AGC controll signal to do this or a spesial program version.
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#qdx QDX and a smoked BS170
#qdx
Hi everyone. I need a little help if you could.
I've had my QDX v4 (12volt) up and running for quite some time with no issues. Yesterday I was doing ft8 on 20m and heard a pop and caught a whiff of magic smoke. The LED light went out.
After investigating I found that one of the bs170's had burned popped open. Maybe I had a bad swr at the moment, I'm not sure.?
I got busy replacing the blown fet and hooked everything back up. I noticed that the frequency and bands weren't changing and the audio was strange with no perceived signals.?
I measured the current draw on power up RX and found it to be about 700ma. I removed all 4 bs170's and the current didn't change. I then removed IC5 and now the current draw is around 900ma.?
I'm at a bit of a loss of what to check next. Can anyone suggest some test points with expected voltage or resistance levels?
Many thanks!
James Shrum - AB9LM
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Re: Theory of operation (circuit theory)?
Hi Peter
There aren't yet full theoretical notes. You can find some stuff in my FDIM 2023 conference proceedings article at and a lot of the design is similar to QDX which is described in some detail in it's manual at . Despite this various material there are still some gaps and a detailed explanation does need to be penned... But there's a lot to do and it hasn't been done yet...
73 Hans G0UPL
Hi. Last evening I finished assembling my QMX and loaded the firmware. Today I¡¯ll see how she performs. Having built the QCX years ago, I keep searching for the alignment instructions but since there were no adjustable pots in the build (except for the LCD screen) can I assume there is no alignment??
It is noted in the assembly manual that the circuit theory is found in another location. Can anyone tell me where I can find the circuit theory?
Is there any alignment needed other than adjusting the coils on the band pass filters?
I appreciate the engineering that went into getting all the functionality into such a small and compact package.
72
Peter/AA2VG
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I am powering my QDX from USB directly like Howard for almost a year and no problems. The only difference in my power mod is I removed IC2, 78M05 altogether from QDX pcb. This clears any 12V to 5V conflict. -- ?
73, Barb, WB2CBA
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Re: QMX FW 17 and side tone clicks
I too am hearing these sidetone clicks in my earphones as I send. I noticed they go away if I raise the sidetone to an uncomfortable level but return when I turn the sidetone level back down.
Keith N8CEP
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Re: Theory of operation (circuit theory)?
Hello Peter,
The design is described in great detail in the QDX manual, you'll find that there's no other alignment other that tinkering with the coils.
Regards,
YO3GFH
op. Adrian
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Re: Noise around 150Hz on digi mode with my
#qmx
Hi Hans,
?
Thanks a lot, I ignore that feature exists on WSJTX.
?
73,
Quentin VA2HSW/F4HSW
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QMX Diagnostic Power Out Vs Meter
My QMX Rev 2 Putty Diagnostic is showing <.5w with a voltage of 10.1. ?Supply voltage into the QMX was 11.9. ?My SWR/power meter is a good CB unit that shows 2watts on 80m, and about 2.5 watts on the other bands. This CB meter should differentiate between .5 and 2.5 watts I would think.
I¡¯ve been making contacts on 20m FT8 on a 4ft magloop that¡¯s only 70% efficient on 20m. A <.5w signal probably wouldn¡¯t be heard on that antenna¡dunno. ?
If the CB meter is wrong, could I have blown my finals and how could I check? ?Could the diagnostic be wrong?
--
Bill Harbour
K4VIB
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Theory of operation (circuit theory)?
Hi. Last evening I finished assembling my QMX and loaded the firmware. Today I¡¯ll see how she performs. Having built the QCX years ago, I keep searching for the alignment instructions but since there were no adjustable pots in the build (except for the LCD screen) can I assume there is no alignment??
It is noted in the assembly manual that the circuit theory is found in another location. Can anyone tell me where I can find the circuit theory?
Is there any alignment needed other than adjusting the coils on the band pass filters?
I appreciate the engineering that went into getting all the functionality into such a small and compact package.
72
Peter/AA2VG
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Hi Hans,
Thanks again for the great QRP Labs products.
You're right about me getting my wires crossed somewhat. I was thinking about the following QMX issue when I made the comment:?. I was also thinking of the 1.5V SMPS transmit bias circuit in the QDX.
I had an unexpected failure of my QDX during initial testing of the diode modification I described. The failure occurred while powered by 5V from the USB cable and then connecting 12V, and the symptoms were similar to what Gunnar explained in his original post. I believe it was a Rev 4 QDX. It has been a few months since this happened, and it sounds like I need to revisit this scenario.
The initial intent of the diode solution was to allow 5V operation via the existing USB connection, while also allowing 12V operation when desired. This solution seems to work reliably as long as, when your want to run full power, you connect 12V first.
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Re: QMX early use fail - dynamic vdd signature
Hi Steve,
This is not the typical cpu VDD short to ground behavior. ?Check with a DVM in continuity mode for VDD shorted to ground on the main board without any other boards plugged into it. ?You can trace where the short is (if there is one) with a milliohm meter. ?If you can¡¯t find it, I¡¯m glad to take a look. ?My backlog for repairs is small.
73,
Jeff
W1NC
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Colin Kaminski
LA1KHA Kjell
Barb WB2CBA