Re: #qmx+ #qmx #qdx Documentation updates
#qmx
#qdx
Could you list the pages that changed so those of us awaiting our QMX+ delivery can update our assembly manuals?? I already printed out the assembly manual to read while awaiting delivery.
On Fri, Jan 3, 2025, 8:01 AM Hans Summers via <hans.summers= [email protected]> wrote: Hi all
Since T37-6 (yellow) toroids suddenly got scarce, some new batches of QDX 80-20m, QMX 60-15m and QMX+ are now being supplied with some T37-10 (shiny black) toroids. I have updated the QDX, QMX and QMX+ manuals to reflect this.?
-- Dale Hardin
KS4NS
Elberta, AL
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#qmx+ #qmx #qdx Documentation updates
#qmx
#qdx
Hi all
Since T37-6 (yellow) toroids suddenly got scarce, some new batches of QDX 80-20m, QMX 60-15m and QMX+ are now being supplied with some T37-10 (shiny black) toroids. I have updated the QDX, QMX and QMX+ manuals to reflect this.?
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Re: QMX(+) Build experience, Poor Audio Filter Sweep/RF Filter Sweep/Image Sweep/ADC IQ test and resolution with new PCM1804
I suspect ESD or power supply damage to an incomplete board would not be repeated once fully built.? ESD damage, to ICs in particular, is often evident only after a few weeks or months...
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Re: QMX(+) Build experience, Poor Audio Filter Sweep/RF Filter Sweep/Image Sweep/ADC IQ test and resolution with new PCM1804
On Wed, Jan 1, 2025 at 11:22 AM, Hans Summers wrote:
QMX is the outstanding problem. We will find a solution to that too.?
The QMX boards could be tested with some sort of bed of nails test fixture that provided the appropriate test signals for IC403 couldn't they?
Use the CLK2 signal attenuated by R513 with a suitable level and phase shift, then the Rx Audio and Image tests should work.? That's enough to test most of the Rx side on an unpopulated board.
?
Yeah like my QCX-mini test fixture:
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Yes, that's the sort of thing I was thinking of, not surprised you have already tried it..
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I understand that it's a lot of work to make but if 1 in 7 of the QMX kits fail because of the PCM1804 problem 100% testing seems essential.? I don't think it's reasonable to keep shipping QMXs untested if that level of failure can be expected, it isn't fair on your customers.
?
Would a test rig that picked up the test signal from R518 and passed it through T401 to the inputs of IC403 work?? Your test harness would provide VCC and VDD and ground, that's 6 or 7 pins.? Run the Rx diagnostics through the USB connection.? This bypasses the LPFs and the BPFs but if they are needed they could be added to the test rig and a single band test done.? The alternative seems to be to connect each board manually using test clips, time consuming and error prone.
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Chris, G5CTH
?
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QMX+ indicates better SWR with antenna disconnected. Issue resolved!
Just in case anyone else gets the same symptoms:-
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I built a v2 PCB QMX+ and all went well until i went to transmit into a dummy load and the swr protection activated and a high swr was indicated via the terminal program. I checked the load with an swr meter and a VNA and it looked fine. I was somehat surprised that when the dummy load was DISconnected the swr dropped as did the swr alarm!
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I suspected an error winding T507 so i spent the next 2 nights rewinding it changing the 4 permutations of winding directions but nothing changed. The DC voltages out of the detector diodes matched what the terninal program was saying.
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On the 3rd night I tried checking resistances, which is hard to do as the windings are DC grounded. I removed T507 yet again and checked the resitances. Measuring across R522 showed 50 ohms. Measuring across the tracks to R520 did not reveal 49.9 ohms! I then measured across the solder pads physically on R520; still not 50ohms. Examination under a USB microscope (i knew it would come in useful one day!) showed a break in the resistive element. I found a 51 ohm resitor as a temporary measure , replaced T507 and all worked perfectly. I subsequently got a 49.9 ohm resitor and put it in.
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Now you can buy blank QMX+ cases from the ship I have now built an ATU100 into one of them (I have one that would work inside the QMX+ box but that would mean hacking the QMX+ front panel, i will wait till the QMX+ software supports it.) The other case has a 3 x 18650 battery pack () ?which powers the radio well through a dropper diode
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Dave
G4FRE
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Re: QMX+ No transmit or receive
Joel,
I had a similar incident on a QRP Labs built QMX+. ?It had lower power output from the factory (3 watts or so which is within spec) and then it had no power output. ?I checked T501 and it didn’t look like the wires had taken up solder completely like I want to see. So I reheated that transformer with high heat and longer application. Now I have even higher power output. ?So trusting the soldering procedure to burn off the lacquer coating on the wire is a not so good an idea in my opinion. ?I would at least scrape some of the coating off before soldering. ?And apply more heat for a longer period of time to complete the connection. ?
Just my humble opinion, but with 65 years of learning from my mistakes my method works for me.? ? Be the REASON someone smiles today.
Dave K8WPE
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On Jan 2, 2025, at 7:48?PM, Joel Macneill via groups.io <joelmacneill1977@...> wrote:
? Hello Chris, hello Ludwig! Wow I've got some interesting news this evening. Those voltages that I said weren't present yesterday, are present today. I can't explain it but I set the radio up on the workbench again this evening and confirmed that there was no voltage at t401 like yesterday, but I did have voltage this evening. And I have the voltage that I need at pins 7 and 9 of IC 403 and at pin 9 of IC 402. I'm not quite sure how to explain this because I didn't do anything to it. When I noticed the voltages were there, I connected the antenna to the BNC and right away I heard a crackle in my headphones. Now I'm getting signal meter deflection and I'm listening to CW on 80 m. I'm going to listen to the other bands as well but I'm also going to go into the area where I last was yesterday and make absolutely sure I do not have a loose connection. Obviously when I was poking around with the meter, something happened. Maybe my trifilar coil could have an intermittent short? I don't know but I'm hoping to find out and I will let you all know. Thanks very much for all of your input!
73s
VY2KW
On Wed, Jan 1, 2025 at 06:14 PM, Joel Macneill wrote:
1) I have continuity from C526 to the anode of each 1N4007 diodes closest to the rear of the radio and from the cathode of?each.?
Joel, thank you very much for your wishes.
I don't understand the thing with the cathodes. To the anode is ok but to the cathode the same time?
?
All the five points are related to the LPF section. If TX is working well the LPF section should be also ok.
IC408 pin#5 only has 2.5v. ?(idle receive)
?
Sorry, my mistake. 2.5 V is ok.
IC402 pin#9 is 0v,?
IC403 pin#7 is ?0v, pin#9 is 0v
Like Chris wrote: 2.5 V from the voltage devider R401 R402 would be ok.
?
IC402 pin#1 0v and pin#3 0v.?
Ok both connected to GND.
That voltage should also be present at the trifilar toroid coil. Perhaps I am not making sufficient connection there or perhaps it's a short?
Later you found this by yourselfe. I think no short. In case of a short it should be close to 0 V AND the same voltage across R402, C406. It's strange to find 0 V at all the three pins to C402 / C403. It means all three windings are affected. It looks like more than one bad connection and / or connecting the windings in a wrong way.
?
I hope fixing T401 will be the solution.
?
73 Ludwig
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QMX+ - Another build experience
Hi all.
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I have completed the build of a V2 QMX+ over the festive period, and the? radio? is working very well indeed.? I did have some issues however and wonder if the excellent assembly instructions could be further improved to help others avoid the pain of removing a soldered in LCD display module.
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The issues I had in the build were mainly with the front panel.? On initial inspection one of the pull up resistors for the was at about 45 degrees to its proper placement and had the metal cap on the end missing.? Fortunately I have a kit of various 0603 resistor values, so no problem to replace.? On visual examination the rest looked to be soldered OK.? When completed however the "Return" button did not work and operation of the encoders was erratic.? After a bit of tracing it was found that the other pull up resistors on the board were damaged.? These are unfortunately located under the soldered in display module which had to be removed.? I did successfully manage this and replaced all the resistors on the board with new ones as they were all suspect - on two of them the values could not be read at all and they had the appearance of being overheated.
I think it would be worth adding a note in the instructions to check the continuity and values of these parts before soldering in the display module.
If there is ever a further revision of the PCB design then these parts could easily be moved to the other side of the PCB so they are accessible.
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There was another fault on the main PCB.? D501 had received a knock somewhere, probably during the manufacturing process and was not in its proper position with the PCB track lifted.? As the other end (nearer the middle of the board) was soldered OK and did not appear strained I surmise that somehow it got knocked while the board was cooling just after soldering.? The part tested OK and was connected to the rest of the circuit as it should be so I left it.
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I also think that the assembly instructions should explain the diagnostic tests that should be carried out before putting the QMX on air and what can be considered acceptable and not acceptable.? The assembly instructions can refer to the operating instructions, but could include a simple list of the tests to be done.? If for example there is a fault with a low pass filter, maybe even as simple as? miscounting the turns and having too many, then the PA will see a high SWR even with a good dummy load attached which could result in the PA expiring if an attempt to transmit at full power is made.? This can be seen during the sweep of the low pass filters - the current increases dramatically as the sweep progresses.??
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Despite the issue with the build quality of the pre-assembled PCB I am very impressed with the radio and am having lots of fun with it.? Brilliant piece of design and engineering.??
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Dave M0WID
?
?
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Re: QMX(+) Build experience, Poor Audio Filter Sweep/RF Filter Sweep/Image Sweep/ADC IQ test and resolution with new PCM1804
If boards with a failed PCM1804 never fail when the part is replaced, that points to counterfeit parts.?
No, it doesn't; counterfeit parts is only one option; there could also be ESD problems causing it, either during assembly, or subsequent handling somewhere along the line; or there could be problems during our bootloader flashing and testing procedures.? ? And I'd not have them stuffed at that assembly house, make it?a hand add at QRP Labs instead.
Just when I thought I was already having the maximum amount of fun possible per day...
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Chris,
?
I am not sure I am reading the chart correctly, but it looks like there is a significant power output difference for the different bands. ?The line color for band is not in the picture.
?
Did you record output power for each band?
?
73
Evan
AC9TU
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Re: I damaged my QCX mini
Ron,
Thanks I’ll go that one, I appreciate the help.?
Rick KC6UXI
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Re: QMX+ No transmit or receive
Hello Chris, hello Ludwig! Wow I've got some interesting news this evening. Those voltages that I said weren't present yesterday, are present today. I can't explain it but I set the radio up on the workbench again this evening and confirmed that there was no voltage at t401 like yesterday, but I did have voltage this evening. And I have the voltage that I need at pins 7 and 9 of IC 403 and at pin 9 of IC 402. I'm not quite sure how to explain this because I didn't do anything to it. When I noticed the voltages were there, I connected the antenna to the BNC and right away I heard a crackle in my headphones. Now I'm getting signal meter deflection and I'm listening to CW on 80 m. I'm going to listen to the other bands as well but I'm also going to go into the area where I last was yesterday and make absolutely sure I do not have a loose connection. Obviously when I was poking around with the meter, something happened. Maybe my trifilar coil could have an intermittent short? I don't know but I'm hoping to find out and I will let you all know. Thanks very much for all of your input!
73s
VY2KW
On Wed, Jan 1, 2025 at 06:14 PM, Joel Macneill wrote:
1) I have continuity from C526 to the anode of each 1N4007 diodes closest to the rear of the radio and from the cathode of?each.?
Joel, thank you very much for your wishes.
I don't understand the thing with the cathodes. To the anode is ok but to the cathode the same time?
?
All the five points are related to the LPF section. If TX is working well the LPF section should be also ok.
IC408 pin#5 only has 2.5v. ?(idle receive)
?
Sorry, my mistake. 2.5 V is ok.
IC402 pin#9 is 0v,?
IC403 pin#7 is ?0v, pin#9 is 0v
Like Chris wrote: 2.5 V from the voltage devider R401 R402 would be ok.
?
IC402 pin#1 0v and pin#3 0v.?
Ok both connected to GND.
That voltage should also be present at the trifilar toroid coil. Perhaps I am not making sufficient connection there or perhaps it's a short?
Later you found this by yourselfe. I think no short. In case of a short it should be close to 0 V AND the same voltage across R402, C406. It's strange to find 0 V at all the three pins to C402 / C403. It means all three windings are affected. It looks like more than one bad connection and / or connecting the windings in a wrong way.
?
I hope fixing T401 will be the solution.
?
73 Ludwig
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Re: 2m/440 cw/ssb qrplabs kit?
I bought a 6 meter transverter from him last year. I tried it with a?QCX with usdx conversion with 10 m filtering and power reduced to 300 mw. Made 6 contacts on FT8?and then the band went dead before I had a chance to try it for SOTA.? Puts out about 10 w.?
-- Jginaz
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Re: QMX(+) Build experience, Poor Audio Filter Sweep/RF Filter Sweep/Image Sweep/ADC IQ test and resolution with new PCM1804
Jeff Moore has never seen a PCM1804 fail after he’s replaced it and he replaces quite a few of them. Jeff is sourcing replacement devices from Digikey and they’re also available directly from TI.com. I tend to agree there’s something amiss in the CM’s procurement process.
Tony
If boards with a failed PCM1804 never fail when the part is replaced, that points to counterfeit parts.? And I'd not have them stuffed at that assembly house, make it?a hand add at QRP Labs instead.
?
Jerry, KE7ER
?
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On Thu, Jan 2, 2025 at 07:56 AM, Jerry Gaffke wrote:
When final test detects a problem with the PCM1804, do they replace it with stock you buy from directly from TI?
Do these parts also fail in the same way at a 15% rate?
It could be your assembly house is sourcing what they believe are parts from TI, but they are counterfeit.
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Evan
I did not really figure out why the peak voltage gets worse at lower frequencies.? In general these peak voltages are caused by the harmonics reflected back into PA transistors by the LPF.? It could be how the higher harmonics stack up because of the particular phase of the reflected higher harmonics.??
?
The plot shows peak voltage vs SWR for 40m to 160m bands
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Re: QMX(+) Build experience, Poor Audio Filter Sweep/RF Filter Sweep/Image Sweep/ADC IQ test and resolution with new PCM1804
If boards with a failed PCM1804 never fail when the part is replaced, that points to counterfeit parts.? And I'd not have them stuffed at that assembly house, make it?a hand add at QRP Labs instead.
?
Jerry, KE7ER
?
?
On Thu, Jan 2, 2025 at 07:56 AM, Jerry Gaffke wrote:
When final test detects a problem with the PCM1804, do they replace it with stock you buy from directly from TI?
Do these parts also fail in the same way at a 15% rate?
It could be your assembly house is sourcing what they believe are parts from TI, but they are counterfeit.
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Re: Release of version 1.2 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#ABS
#ATU
#PSU
#QMXplus
Dear Stan,
?
please put me on the 2nd list, if you descide to have one.
Best regards,
Stefan
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Re: Release of version 1.2 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#ABS
#ATU
#PSU
#QMXplus
Please include me in the next group buy (if it materializes). Thanks for the effort on this.
Paul - K9MR
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On 2024-12-31 00:22, Stan Dye via groups.io wrote: To all who are asking about being part of a new group buy of the ABS
add-on for the QMX+:
Cal and I have you on our list for a potential new group buy of the
ABS boards and components. Sorry for the delay in responses.
We are still busy getting the current group buy out to the 30+ who
subscribed to the initial buy, and resolving some (hopefully minor)
issues we have found in further testing. When we have completed that,
we will look at logistics, etc., and make a decision about another
group buy for those who missed the first one. The prices for a second
group buy, if we decide to continue with it (which is likely), will
depend on the number who subscribe to it, since the cost depends on
quantity discounts. Please be patient with us as we get the first buy
completed.
Here are the ones we have on the list so far who have requested to be
part of a second group buy:
ZL1ANY Stephen
W9LG Michael
KF7EJ Will
K7RAN Randy
KS4NS Dale
OZ1ES Erik
Nico Smith
Dave Campbell
Thank you,
Stan KC7XE
Links:
------
[1] /g/QRPLabs/message/136293
[2] /mt/110280831/427835
[3] /g/QRPLabs/post
[4] /g/QRPLabs/mutehashtag/abs
[5] /g/QRPLabs/mutehashtag/atu
[6] /g/QRPLabs/mutehashtag/psu
[7] /g/QRPLabs/mutehashtag/qmxplus
[8] /g/QRPLabs/editsub/427835
[9] /g/QRPLabs/leave/830565/427835/1452075636/xyzzy
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Re: CW Practice / Rag Chew
Good job, Ed.
From coastal TX I saw RBN spots but none reaching this far south.? Hopefully the unsettled Geo will settle by 1/3/25.??
Charles K5KXJ
On Thursday, January 2, 2025 at 10:39:38 AM CST, Ed Kwik via groups.io <ekwik@...> wrote:
On 1/2/25 I had a CW practice / rag chew
session on 40 meters. I worked three stations:
Conditions were very poor. SSN = 163, SFI = 219, A = 86, K = 5
so the band was pretty noisy.
I will be doing another CW on the air practice session Friday
01/03/25 . Anyone is welcome. This practice is intended
for operators who are new to CW or they need some practice. IT
DOES NOT MATTER HOW POOR YOUR CW IS. Mistakes are OK. Poor fists
are OK. Slow speed is OK. Really slow speed is OK. This practice
is meant for you to improve your CW. I will do my best to adjust
to your skill level. Operate at any power level. If several
stations show up, I will operate as a round-table control
station. I will do it as a round-table so everyone gets a chance
to transmit. Please listen to my directions.
Details:
Time - 10:00 AM Eastern Time / 15:00 UTC
Band - 40 Meters
How to find me - I will find a clear frequency and call CQ. Go
to the Reverse Beacon Network and search for my call sign AB8DF.
That will tell you what frequency I am on.
Tune your station to that frequency and if you hear me give me a
call. If there is a QSO in progress, please wait for a break in
the action. Then send your callsign. If I hear you, I will
invite you to join the QSO and start a round-table QSO.
Reply to this email if you have questions.
IT DOES NOT MATTER HOW POOR CW IS
Ed
AB8DF
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Re: 2m/440 cw/ssb qrplabs kit?
I have a Ten-Tec 1210 transverter that should work just fine with a high-band QMX. W1GHZ had designed a simple 2 metre transverter for the Flex-1500 that could probably be reworked by someone handy with Kicad...
72 de Russ, va3rr
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Re: Wanted: low power 50 MHz. linear amplifier
I like my Hardrock 50 and there is/was a low-power driver amp option.? If no longer available it would not be too difficult to integrate a similar driver.
73, Don N2VGU
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Dale Hardin KS4NS
Bruce Akhurst
David Wilcox K8WPE
va3rr
Donald S Brant Jr