Recently a fellow ham sent me a QMX rig to fix.??This is to be my 100th QMX that I have fixed - assuming that I accomplish that with this one.???I wanted to share the journey.??I found this one interesting.??This is a Rev 2 QMX with rev 14 firmware.??Wound for 12V.??This is the first part of a story - the diagnosis and how I arrived at it.??I wanted to share because this is more interesting than most and it may help someone else.??More will be posted later.
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?My usual routine with a new rig is to disassemble, inspect, clean??and inspect again.??I use a 10x stereo microscope for everything with very bright side and overhead lights.??I scrape flux off, use 99% isopropyl alcohol to clean with an extra soft toothbrush.??Then I inspect again.??I can fix almost all rigs this way.??There are always solder blobs, solder balls, cold solder joints in every rig that comes to me.
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This rig came in very clean.??No excess flux, no bad solder joints, no solder splashes.??It did have a few long pins that ended up shorting to the case, adjacent boards and wreaked a bit of havoc.??I fixed those before proceeding.
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After applying power at 7V with current limits, it came up only with top row black boxes.??No backlight, nothing on PUTTY.??Looking with a scope I could see the 3.3V rail was good and 3.3V PWM was within range.??But the 5V rail was sitting at about 5.8-5.9 V and the 5V PWM was at about 78% as measured on my scope.??Not Good!??But I knew the CPU was running enough to produce PWM signals for the SMPS boards.??Thats good!
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I tested the SMPS power boards on my homemade test fixture.??They were fine.??I tested for near shorts or low resistance on the 5V rail.??It looked fine also.
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I put the SMPS boards back into the rig and plugged in the controls board.??I also installed the jumper to force the QMX into firmware update mode.??That worked.??The QMX came up wit the “disk drive” on my Linux desktop.??I installed rev 16 firmware knowing that Hans had fixed a bug in initializing the EEPROM.??I thought the forced factory reset upon installation of Rev 16 might shed some light.??It did.??Now the rig came up immediately into Diagnostic mode.??It’s the only screen that will come up in PUTTY if something is seriously wrong.??I could see that the 5V rail was at 78% duty cycle as I saw on my scope but the reported voltage to the CPU was only 4.8 volts.??The CPU was trying its hardest to reach 5V but it maxed out at 78% and couldn’t get there.??I measured the ADC_5V signal on the board and my scope read 2.4V.??That is consistent with the diagnostic screen reporting 4.8V since there is a 2x divider in the circuit.
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ADC_5V only goes from the SMPS board to the CPU.??Something was clamping it at 2.4V.??It had to be a short on the SMPS (no, because I tested those separately), the main board in the traces (possible, but unlikely), or in the CPU (UGH!).??I lifted pin 32 of the cpu and confirmed that indeed the CPU was clamping that line at 2.4 volts.??After lifting that pin, the board showed 2.95V for ADC_5V.??And that CPU pin 32 in the air showed 2.4V.??Proof enough for me.
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So this means that replacing the CPU is the only option.??This rig has sentimental value to its owner, so he said please proceed.??I have a few bare boards with programmed CPUs that I have just for this kind of occasion.
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Tomorrow I will proceed with the operation.??I have to accomplish that in the morning when I am at my best and after only 1 cup of coffee.??I’ll post my progress here.
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73 for now
Jeff
W1NC
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Re: QMX locks up during keying practice
Is the "S" showing in the display just to the right of the frequency when this happens? That would mean lock out on high SWR. If that's happening, check your dummy load or the coax or adaptor you are using to connect it to the QMX.? In the meantime, you should probably be using the Practice mode found in the CWKeyer menu. This allows you to practice without generating any RF.
Have fun ... Ron
I have been using the QRPLabs dummy load connected to my QMX, with a Begali paddle, to practice my morse sending. The issue I have is a little random in that the length of time that things are ok varies. After perhaps 1 to 2 minutes of sending with decoded letter appearing correctly on the screen the QMX will just lock up - i.e. no further tones heard or characters displayed. I have to turn off the power then turn on again to continue 'sending' morse. Please let me know if a short video demo would help make theissue clear.
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Thanks for this suggestion, Fernando. I found some very useful information in that book.
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Re: QMX locks up during keying practice
What version of firmware?
-mike/w1mt
I have been using the QRPLabs dummy load connected to my QMX, with a Begali paddle, to practice my morse sending. The issue I have is a little random in that the length of time that things are ok varies. After perhaps 1 to 2 minutes of sending with decoded letter appearing correctly on the screen the QMX will just lock up - i.e. no further tones heard or characters displayed. I have to turn off the power then turn on again to continue 'sending' morse. Please let me know if a short video demo would help make theissue clear.
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Re: 50W PA Input SWR 3 and up! What can I mess with?
The amp is (more ore less) working. Heap down your abuse upon me for my malignant deeds, of which I will speak of presently.... Center pin of q4 got disconnected from one of the resistors.? Works now, but SWR is high. On a short piece of coax from TX to PA, the SWR is 2.5 and QMS shows 5.4W. Uncomfortable. Long coax shows 1.9 SWR and 2.4W, PA draws 45W at 18V, heat is good, definitely getting out.? The amp is (more ore less) working. Heap down your abuse upon me for my malignant deeds, of which I will speak of presently....  Center pin of q4 got disconnected from one of the resistors.? Works now, but SWR is high. On a short piece of coax from TX to PA, the SWR is 2.5 and QMS shows 5.4W. Uncomfortable. Long coax shows 1.9 SWR and 2.4W, PA draws 45W at 18V, heat is good, definitely getting out.?  Getting out though! Weirdness with the cable has me head scratching, and I prefer to run the long (5 meter) cable from the TX to PA for the apparent attenuation. Did Amazon ship me spark plug wire with BNC on the end? LOL wouldn't surprise me.?? Thanks for all the help. I have other data, but this is the 3rd time I've tried to post these images and the forum keeps losing the post. Still feels like a hack, so wondering what others think? Andy KA1PLU
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QMX locks up during keying practice
I have been using the QRPLabs dummy load connected to my QMX, with a Begali paddle, to practice my morse sending. The issue I have is a little random in that the length of time that things are ok varies. After perhaps 1 to 2 minutes of sending with decoded letter appearing correctly on the screen the QMX will just lock up - i.e. no further tones heard or characters displayed. I have to turn off the power then turn on again to continue 'sending' morse. Please let me know if a short video demo would help make theissue clear.
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Thank you Hans…
It will be very exciting when his radio can do sideband.
i’m looking forward to it and I do know I have to be patient because you don’t release updates until you’re 99% certain they’re perfect and I can deal with that.
thank you for the great work!
N2HHH
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Can the choice be retained by mode???
Charles K5KXJ
On Thursday, February 15, 2024 at 06:46:57 AM CST, Cliff <ae5zaham@...> wrote:
May I caution here, digital modes are all USB so one does not want the lower bands to change to LSB.
Hello Howard
Yes you are correct, at the moment there is only the one USB/LSB setting and it applies to the whole radio, not by band. I will fix it eventually, particularly when it comes to the proper SSB implementation.? On Thu, Feb 15, 2024 at 8:47?AM Howard Lamhut < Howardlam@...> wrote: I have the QMX And I love this radio.The one thing I’m not certain if it has or has not been addressed is I love to listen to upper and lower side band audio on 40 m and 20 m.
The only issue is 40 m is lsb ?and 20 m is usb and the qmx does not seem to remember these settings specific to the band.? At this point in time if I set it for 40 m then go to 20 m it forces me to go back to the menu to change it from LSB to Usb.
on the upside the single side band audio on this radio is absolutely superb.
is my observation on this issue correct?
on the final note I have built 4 QRP labs radios and I’m loving all of them. ?
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Re: QCX mini became a little deaf after transmitting near a telescopic balcony antenna
Glad you got it working Yuri. Best 73…Ron
Thank you Ron again!
I checked output pins before soldering and no shorts or low resistance to ground.
After that I soldered FST3253 from QRP-Labs and everything works like before. Only performed alignment again to be on the safe side.
Voltage on IC legs (from troubleshooting page) as expected about 2.4V.
br,
Yuri
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May I caution here, digital modes are all USB so one does not want the lower bands to change to LSB.
toggle quoted message
Show quoted text
Hello Howard
Yes you are correct, at the moment there is only the one USB/LSB setting and it applies to the whole radio, not by band. I will fix it eventually, particularly when it comes to the proper SSB implementation.? On Thu, Feb 15, 2024 at 8:47?AM Howard Lamhut < Howardlam@...> wrote: I have the QMX And I love this radio.The one thing I’m not certain if it has or has not been addressed is I love to listen to upper and lower side band audio on 40 m and 20 m.
The only issue is 40 m is lsb ?and 20 m is usb and the qmx does not seem to remember these settings specific to the band.? At this point in time if I set it for 40 m then go to 20 m it forces me to go back to the menu to change it from LSB to Usb.
on the upside the single side band audio on this radio is absolutely superb.
is my observation on this issue correct?
on the final note I have built 4 QRP labs radios and I’m loving all of them. ?
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Re: QCX mini became a little deaf after transmitting near a telescopic balcony antenna
Thank you Ron again!
I checked output pins before soldering and no shorts or low resistance to ground.
After that I soldered FST3253 from QRP-Labs and everything works like before. Only performed alignment again to be on the safe side.
Voltage on IC legs (from troubleshooting page) as expected about 2.4V.
br,
Yuri
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Hello Howard
Yes you are correct, at the moment there is only the one USB/LSB setting and it applies to the whole radio, not by band. I will fix it eventually, particularly when it comes to the proper SSB implementation.?
On Thu, Feb 15, 2024 at 8:47?AM Howard Lamhut < Howardlam@...> wrote: I have the QMX And I love this radio.
The one thing I’m not certain if it has or has not been addressed is I love to listen to upper and lower side band audio on 40 m and 20 m.
The only issue is 40 m is lsb ?and 20 m is usb and the qmx does not seem to remember these settings specific to the band.?
At this point in time if I set it for 40 m then go to 20 m it forces me to go back to the menu to change it from LSB to Usb.
on the upside the single side band audio on this radio is absolutely superb.
is my observation on this issue correct?
on the final note I have built 4 QRP labs radios and I’m loving all of them.
?
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I have the QMX And I love this radio.
The one thing I’m not certain if it has or has not been addressed is I love to listen to upper and lower side band audio on 40 m and 20 m.
The only issue is 40 m is lsb ?and 20 m is usb and the qmx does not seem to remember these settings specific to the band.?
At this point in time if I set it for 40 m then go to 20 m it forces me to go back to the menu to change it from LSB to Usb.
on the upside the single side band audio on this radio is absolutely superb.
is my observation on this issue correct?
on the final note I have built 4 QRP labs radios and I’m loving all of them.
?
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Sure Cliff, I tested the QMX both in WSPR independently without using software and in CW, I made a local QSO on 20 meters and the power output is 7 W, so there shouldn't be any problems, I'll have to look at the manual for the settings .? thanks 73
Giuseppe iu8eun
By software I was thinking of ones like fldigi that is used for digital modes as fldigi and some other digital mode software has difficulty with the QMX if Transmit ID is on. It will transmit once and never again unless the QMX is power cycled.
I suspect WSPR should work fine.
My other question was if you tested the QMX transmit in the QMX's builtin firmware config utility to verify it transmits.
On Feb 14, 2024, at 13:54, GIUSEPPE < iw8rsb@...> wrote:
Hi Cliff, what do you mean what software do you broadcast with??? I simply updated the firmware and figured out the QMX with the wspr data.? The first transmission went well, the subsequent ones didn't have any RF output even though I had the SWR at 1 or less than 1. I don't know what it could be.? 73
Giuseppe iu8eun What software are you using to transmit?
Does it transmit in hardware test mode when in the config mode via putty?
73,On Feb 14, 2024, at 04:21, GIUSEPPE < iw8rsb@...> wrote:
good morning everyone, yesterday morning I wanted to do a test with the QMX second high band version with firmware 1_00_015, the first transmission went very well, the time was set perfectly by the qlg1 and it gives me 7 w output, not a single band antenna perfectly tuned to 20 meters with swr 1 or -, the problem is that on the second transmission and all subsequent ones it did not transmit any power, the swr protection was deactivated, have any of you had the same problem or know what it could be, it would be the case update the firmware to 1_00_016?? Thank you and good day.
Giuseppe iu8eun Hi Philip
I just did a single WSPR transmission on 40m with the GPS plugged in. See attached... Not burning any DX but then again my power supply is at 7.5V (12V QMX) and it's 40m and still daytime; furthermore my antenna wire (long side of the OCFD) fell down and lies on the metal roof. It really doesn't work well, it stops the internet working in my entire house, even at such low power! Anyway no SWR tripping...
On Sat, Feb 10, 2024 at 5:11?PM Hans Summers via ??<hans.summers= [email protected]> wrote: Stand alone only.
Then that's very strange. I'd wonder in that case if there is some common mode feedline issue (a.k.a. grounding?issue,? a.k.a. in shack), and perhaps adding your GPS connection does something that pushes the SWR over the limit - though SWR and common mode currents aren't the same the causes and symptoms have some relation... to test it, I'd suggest checking with a dummy load.?
If you do still see it on the dummy load then please could you show me exactly what WSPR settings you used and describe it so I can try to reproduce it? Because here everything is running just fine on WSPR with the GPS connected. As a general rule, if there's a software bug, I have?to be able to reproduce it before I can fix it.?
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By software I was thinking of ones like fldigi that is used for digital modes as fldigi and some other digital mode software has difficulty with the QMX if Transmit ID is on. It will transmit once and never again unless the QMX is power cycled.
I suspect WSPR should work fine.
My other question was if you tested the QMX transmit in the QMX's builtin firmware config utility to verify it transmits.
toggle quoted message
Show quoted text
On Feb 14, 2024, at 13:54, GIUSEPPE < iw8rsb@...> wrote:
Hi Cliff, what do you mean what software do you broadcast with??? I simply updated the firmware and figured out the QMX with the wspr data.? The first transmission went well, the subsequent ones didn't have any RF output even though I had the SWR at 1 or less than 1. I don't know what it could be.? 73
Giuseppe iu8eun What software are you using to transmit?
Does it transmit in hardware test mode when in the config mode via putty?
73,On Feb 14, 2024, at 04:21, GIUSEPPE < iw8rsb@...> wrote:
good morning everyone, yesterday morning I wanted to do a test with the QMX second high band version with firmware 1_00_015, the first transmission went very well, the time was set perfectly by the qlg1 and it gives me 7 w output, not a single band antenna perfectly tuned to 20 meters with swr 1 or -, the problem is that on the second transmission and all subsequent ones it did not transmit any power, the swr protection was deactivated, have any of you had the same problem or know what it could be, it would be the case update the firmware to 1_00_016?? Thank you and good day.
Giuseppe iu8eun Hi Philip
I just did a single WSPR transmission on 40m with the GPS plugged in. See attached... Not burning any DX but then again my power supply is at 7.5V (12V QMX) and it's 40m and still daytime; furthermore my antenna wire (long side of the OCFD) fell down and lies on the metal roof. It really doesn't work well, it stops the internet working in my entire house, even at such low power! Anyway no SWR tripping...
On Sat, Feb 10, 2024 at 5:11?PM Hans Summers via ??<hans.summers= [email protected]> wrote: Stand alone only.
Then that's very strange. I'd wonder in that case if there is some common mode feedline issue (a.k.a. grounding?issue,? a.k.a. in shack), and perhaps adding your GPS connection does something that pushes the SWR over the limit - though SWR and common mode currents aren't the same the causes and symptoms have some relation... to test it, I'd suggest checking with a dummy load.?
If you do still see it on the dummy load then please could you show me exactly what WSPR settings you used and describe it so I can try to reproduce it? Because here everything is running just fine on WSPR with the GPS connected. As a general rule, if there's a software bug, I have?to be able to reproduce it before I can fix it.?
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Hi Cliff, what do you mean what software do you broadcast with??? I simply updated the firmware and figured out the QMX with the wspr data.? The first transmission went well, the subsequent ones didn't have any RF output even though I had the SWR at 1 or less than 1. I don't know what it could be.? 73
Giuseppe iu8eun
What software are you using to transmit?
Does it transmit in hardware test mode when in the config mode via putty?
73,
On Feb 14, 2024, at 04:21, GIUSEPPE < iw8rsb@...> wrote:
good morning everyone, yesterday morning I wanted to do a test with the QMX second high band version with firmware 1_00_015, the first transmission went very well, the time was set perfectly by the qlg1 and it gives me 7 w output, not a single band antenna perfectly tuned to 20 meters with swr 1 or -, the problem is that on the second transmission and all subsequent ones it did not transmit any power, the swr protection was deactivated, have any of you had the same problem or know what it could be, it would be the case update the firmware to 1_00_016?? Thank you and good day.
Giuseppe iu8eun Hi Philip
I just did a single WSPR transmission on 40m with the GPS plugged in. See attached... Not burning any DX but then again my power supply is at 7.5V (12V QMX) and it's 40m and still daytime; furthermore my antenna wire (long side of the OCFD) fell down and lies on the metal roof. It really doesn't work well, it stops the internet working in my entire house, even at such low power! Anyway no SWR tripping...
On Sat, Feb 10, 2024 at 5:11?PM Hans Summers via ??<hans.summers= [email protected]> wrote: Stand alone only.
Then that's very strange. I'd wonder in that case if there is some common mode feedline issue (a.k.a. grounding?issue,? a.k.a. in shack), and perhaps adding your GPS connection does something that pushes the SWR over the limit - though SWR and common mode currents aren't the same the causes and symptoms have some relation... to test it, I'd suggest checking with a dummy load.?
If you do still see it on the dummy load then please could you show me exactly what WSPR settings you used and describe it so I can try to reproduce it? Because here everything is running just fine on WSPR with the GPS connected. As a general rule, if there's a software bug, I have?to be able to reproduce it before I can fix it.?
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Re: IQ mode Enabled on version 16
#qmx
Thanks Adrian and Jim,
Glad I am not the only one.? Being a CW wannabe, but no where close to actually using it effectively, the SDR functionality is quite important to me, and seriously, the QMX pulls stations from everywhere.? It is absolutely great.??
No worries - will stick to V-14 until our guru "Hans" presents a solution.
73 de ZR6TM
Timo
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What software are you using to transmit?
Does it transmit in hardware test mode when in the config mode via putty?
toggle quoted message
Show quoted text
On Feb 14, 2024, at 04:21, GIUSEPPE < iw8rsb@...> wrote:
good morning everyone, yesterday morning I wanted to do a test with the QMX second high band version with firmware 1_00_015, the first transmission went very well, the time was set perfectly by the qlg1 and it gives me 7 w output, not a single band antenna perfectly tuned to 20 meters with swr 1 or -, the problem is that on the second transmission and all subsequent ones it did not transmit any power, the swr protection was deactivated, have any of you had the same problem or know what it could be, it would be the case update the firmware to 1_00_016?? Thank you and good day.
Giuseppe iu8eun Hi Philip
I just did a single WSPR transmission on 40m with the GPS plugged in. See attached... Not burning any DX but then again my power supply is at 7.5V (12V QMX) and it's 40m and still daytime; furthermore my antenna wire (long side of the OCFD) fell down and lies on the metal roof. It really doesn't work well, it stops the internet working in my entire house, even at such low power! Anyway no SWR tripping...
On Sat, Feb 10, 2024 at 5:11?PM Hans Summers via ??<hans.summers= [email protected]> wrote: Stand alone only.
Then that's very strange. I'd wonder in that case if there is some common mode feedline issue (a.k.a. grounding?issue,? a.k.a. in shack), and perhaps adding your GPS connection does something that pushes the SWR over the limit - though SWR and common mode currents aren't the same the causes and symptoms have some relation... to test it, I'd suggest checking with a dummy load.?
If you do still see it on the dummy load then please could you show me exactly what WSPR settings you used and describe it so I can try to reproduce it? Because here everything is running just fine on WSPR with the GPS connected. As a general rule, if there's a software bug, I have?to be able to reproduce it before I can fix it.?
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Re: Removing SOIC Chips (QMX IC402)
On Tue, Feb 13, 2024 at 05:13 PM, Bruce Akhurst wrote:
Brain surgery on your latest radio is probably *not* the right way to gain
initial experience
I am NOT new to using hot air to solder SMT. However, removal is something I have only done a couple of times before, on boards that were less dense, hence the request for suggestions. I like the idea of a wooden stick - I have some that I used for winding the QMX toroids that would be applicable. 73 JRJ W9IYN
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Re: 50W PA Input SWR 3 and up! What can I mess with?
Wonderful suggestions - I will check these this evening. T1 has been checked and double checked (and wound twice just for fun) so I don't suspect it. But the other parts deserve a triple check, and it's even possible that D1 is in fact bad or backwards.
I should add that RX performance seems fine with the PA inline (and it must be powered with the green light on only, of course) and power consumption when keyed also increases to a value that seemed inline with expectations with a modest input power, but perhaps I made an error. I will borrow the de-soldering gun from work this evening and report back to the group with my findings and any cautionary tales.?
I really appreciate everyone helping me with my amp. Thank you!
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Ronald Taylor
Howard Lamhut
Yury SP2RM
cube1us