Re: QMX mid band 60m reassignment
60m IS available in the US, but the channels make it rather useless too. So I second the effort to reprogram that slot. On the other hand, upgrading your license sounds like a pretty good idea!
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73, Dan? NM3A
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Just finished building my QMX Midband. Everything seems to be working fine except that the output on 15m is 3dB below that on the other bands. Here is output power by band and by voltage:
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The scans look more or less OK except for a few outliers:
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Image sweep on 60m is pretty poor:
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on the other bands (e.g., 20m) it looks OK:
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SWR sweep (into a dummy load) looks OK except for 15m:
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I checked my dummy load with my VNA. The SWR is practically 1 (return loss <-30dB) and flat from 0-50MHz. So not sure why the QMX SWR sweep on 15m is so bad.
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ADC I/Q test looks good:
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Haven't been able to test the QMX on the air except for two FT8 QSOs which were working fine.
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This is my second QMX. The first QMX I built was a Highband and while it was working for a while, the sweeps were inconsistent (the ADC I/Q test was horrible) and it suddenly stopped working. My second attempt of building a QMX (this Midband version) seems to have gone better.
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Any thoughts on the low output power at 15m and the poor image sweep and SWR sweep on 60m and 15m, respectively?
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73,
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Andreas, K6AKW
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QMX+ Displayed Voltage Low
Got my QMX+ up and running today. The unit is configured for 12 volt operation and I have?
made sure that my input voltage is 12 volts or less. My battery has a nominal voltage other
than 12 volts, so I used the advice on adding diodes to the battery leads to drop the input
voltage to the QMX. I've got a measure voltage of 11.75 at the terminal but the display on?
my QMX+ indicates that my voltage is 8 volts. Additionally, my transmit power is approximately
1 watt on 80 and 20 meters. I have not tried the other bands yet. The receiver is working?
well and overall the unit appears to be functioning properly. Any advice on the voltage question
would be greatly appreciated.
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Corey (WB0RXQ)
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Re: QMX New build - no flash drive - how to troubleshoot?
so far I get
- correct BAT_LEVEL value
- PWR_ON pulled down when left encoder depressed
no 3.3 volts present at ?LIN_REG_EN
when depressing the left rotary encoder the voltage at LIN_REG_EN goes to .75 3/4 of a volt but never 3.3 regardless of BATT input voltage.
I wonder if that means I have an issue with my PCB #2?
Cheers!
~Gordon
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Thanks Hans. One other note of possible interest. When Message 2 completes, it immediately begins Message 1 with the digit "8", then sends Message 1, which in my case is my call: N7RCS. All my other Messages are blank and never had anything entered into them.
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Jim?
N7RCS
Palm Bay, FL
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Re: QMX New build - no flash drive - how to troubleshoot?
On Mon, Jul 15, 2024 at 02:41 PM, @Ludwig_DH8WN wrote:
I think you came only to the first step of the description. Maybe one of the relevant connections to/from the SMPS boards is not ok. Checking the mentioned signals and levels you should find the failure. Please be aware a failure may also exist between the pin headers of the main board and the SMPS.
Ludwig,
Thank you for the guidance & fast response!
I'm going to give this a shot tonight.
Best regards!
~G
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Sorry, figured it out: I was in practice mode in CW, thus the P and no RF output.
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73,
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Andreas, K6AKW
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Re: QMX New build - no flash drive - how to troubleshoot?
?the current draw is only .05 MA if the left encoder is pressed down. when I release it goes back to zero.
Gorden, in this document from QRP Labs Wiki you find a description of the switch on process, about the levels of some signals and also a link to a sketch to find these signals. ?
I think you came only to the first step of the description. Maybe one of the relevant connections to/from the SMPS boards is not ok. Checking the mentioned signals and levels you should find the failure. Please be aware a failure may also exist between the pin headers of the main board and the SMPS.
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73 Ludwig
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Does anybody know what the P at the end of the second line means?
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73,
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Andreas, K6AKW
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Re: QMX mid band 60m reassignment
The 60m band is not available in VK so similar "waste" here.
Replacing it with 80m would work, receiver performance should be ok.
But you would need to check the LPF as it may not have enough harmonic attenuation.
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73,
Warren.
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Re: QMX mid band 60m reassignment
Why not go for a license upgrade?
On Mon, Jul 15, 2024 at 3:21?PM Samantha Collins via <samcollins910= [email protected]> wrote: Just ordered a mid band 60 - 15m?
As I'm just a lowly intermediate license holder and therefore not allowed on 60m it'll be an entirely wasted band.?
Can I resign that filter for anything else ???
Seems a shame wind the torroids and tune the band for a band I can't use...
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Michigan QRP Club Zoom Chat Report 7/11/24
Zoom Notes 11 July 2024 We had eight folks attend last week’s Michigan QRP Club’s Zoom meeting.
Ed AB8DF Pete WK8S Tony W8CDC Stuart M0SGV Tim N7TDB Jim K8DDV Carlos TBD Casey KC9IHL
The topic was Field Day 2024. Ed gave a rundown on what he did for field day. Stuart wanted an explanation of what is Field day. Ed, Tony and Casey did their best to explain what Field day is. It is not a contest. It was started many years ago and has gravitated on club participation. Food at FD can be a big deal for some clubs. Old guys seem to be the most of participants and the trend is to smaller groups and fewer of them. The Ham population is aging. Some of the bigger clubs do VE exams. There was a hope that the recent popularity of POTA would influence the amount of activity on Field Day. Sprit of FD was originally doing emergency messages and to simulate an emergency. It is a fun thing. Other items that were discussed were: 13 colonies POTA conditions Xegiu? 6200 reviews Trading radios. Carlos has a KH1 he wants to trade for another rig. Getting on the air with CW. Just do it. Pink Slips from FCC ARRL Spanmaster receiver Second harmonics FCC and white vans. Shack pictures How to trade a radio with someone you do not know ? Weather
Next weeks topic is keys. Anyone can take the floor and tell us about their keys. We will go one by one until all have had a chance to have the floor. Files, pictures and presentations can be shared if you have any. There will be time for comments and questions. Please try to stay muted when someone has the floor.
Ed AB8DF
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QMX mid band 60m reassignment
Just ordered a mid band 60 - 15m?
As I'm just a lowly intermediate license holder and therefore not allowed on 60m it'll be an entirely wasted band.?
Can I resign that filter for anything else ???
Seems a shame wind the torroids and tune the band for a band I can't use...
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I don't think the display issue is relevant to this unless you are having display troubles too.? What is relevant though is that a low level signal from the internal generator used for those alignment tests also, sometimes, points to the signal not getting through the lowpass filter. Receive and transmit RF paths go through there, as well as the test signal from the internal signal generator. You might want to check the turns counts again, as well as verify the right capacitors are installed in the LPF. But that along with the voltages you will measure may point to the general area of the receiver circuit that's having problems. Good luck .. .73 .. .Ron
Thanks Bruce for mentioning the bad joints. For my own edification, would you be able to tell me (maybe by referencing the picture) which joints look the most problematic? I ask because I did inspect the joints, and while some of them looked a bit ugly I didn't see any that looked obviously bad. It's likely this is just because my eye for bad joints is not yet well-trained, so helping me find the bad ones would be a great help.
In general, is it possible to detect bad joints by checking continuity on either side of the board? Or are there issues that wouldn't be detected with this test?
I was not using a dummy load; I was using my multi-band HF antenna that should have low enough SWR on 20m. (I am aware this is generally considered bad practice; I don't have a good dummy load at my test bench, only an old ATU with an internal dummy load that is annoying to use. Clearly I should have gotten the QRP Labs dummy load kit along with the QCX+...) I'll re-run the RF power test with the dummy load and see if the numbers change substantially. I believe I correctly set the radio for 20m operation, but I will check again.
Ron, I will do those measurements tonight and reply here with the results. I did do the alignment procedures. The bandpass filter alignment tone is audible, but much quieter than the manual led me to expect. (I did not have to take my headphones off during the test.) The I/Q balance and high and low phase alignments do not seem very responsive to changes in the volume knob (or, for that matter, to turns of the screw on the variable resistors). After watching one of your YouTube videos about the QCX+, I tested the resistance across the three terminals of the volume pot; they seem to be correct.
One other piece of information that might be relevant is that I initially soldered the LCD screen to the front plate using the wrong nylon spacers, and so had to de-solder it, remove it, and resolder it. I used a plunger-type desoldering tool to remove the solder, but to remove the LCD and its pin headers from the plate I had to apply a good amount of force. After doing this, I found some brown material on the pins. Is it possible I damaged the front plate PCB contacts by doing this? Would this damage be detectable and/or fixable?
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Sandy,
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Your guidance was spot on!
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A double press of the TUNE knob displays the Message list then a single press of the same TUNE knob produces only a single transmission of the message. This is how I was initiating message transmission. As you say, if the LEFT button (Keyer/RIT/Menu) is pressed instead of the TUNE knob, then the message is transmitted with the selected delay and number of repeats.
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Operator error strikes again!?
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I am so pleased that there is no problem. Thanks very much for your reply.
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Regards 72,?
Roy-KD1RT
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QMX New build - no flash drive - how to troubleshoot?
Hi folks!
I just completed assembly of my QMX and am eager to validate and tune it.
upon applying power and usb-c I do not see a flash drive.
QMX V3 device & Debian (12) Linux
- lsusb shows no new devices
- dmesg shows no new kernel events
- tried holding the left rotary control down for various iterations of time 1,5,10,20 seconds etc.
- poured over all the boards multiple times with magnification and good lighting.
- all diode polarities validated (installed right way round.
- I tested all the continuity test points described in the build manual
- tried different cables, different PC, different OS validated my cables using smartphone and usb drive
- I looked for the possible short on the mosfets on the power supply daughter cards no short between the tab any other traces.
Not sure of my next step in troubleshooting.
Also I noted that when testing voltages on the SMPS 5v supply
- I see the input voltage at whatever I set it 8-12volts
- I hear the audio amp pop in headphones when pressing left encoder
- the current draw is only .05 MA if the left encoder is pressed down. when I release it goes back to zero.
- I never see other voltages apart from the input voltage on either power supply board.
Could my issue be the SMPS board(s)?
What should my next troubleshooting steps be?
Best regards & 73's
Gordon Young - WA8Q
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Re: QMX+ Build Report and Low Power Question on 40m and 30m
On Mon, Jul 15, 2024 at 08:32 PM, M0WAS wrote:
Up to 1.6W on 40m and 0.75W on 30m now. Resoldered and jiggled about the windings. I think next step is taking them out completely and just really tightening up the turns. The fact that doing that and nothing else has increased the power output on 30m from 0.25W to 0.75W means it's all to do with them I think.
?Just to add a question. There's obviously reduced flow here, or something's not right anyway, should I refrain from any sort of transmitting on 40m while it's well below 3W? I assume anything from 2.5W and up is considered 'okay'?
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Re: QMX+ Build Report and Low Power Question on 40m and 30m
Up to 1.6W on 40m and 0.75W on 30m now. Resoldered and jiggled about the windings. I think next step is taking them out completely and just really tightening up the turns. The fact that doing that and nothing else has increased the power output on 30m from 0.25W to 0.75W means it's all to do with them I think.
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Thanks Bruce for mentioning the bad joints. For my own edification, would you be able to tell me (maybe by referencing the picture) which joints look the most problematic? I ask because I did inspect the joints, and while some of them looked a bit ugly I didn't see any that looked obviously bad. It's likely this is just because my eye for bad joints is not yet well-trained, so helping me find the bad ones would be a great help.
In general, is it possible to detect bad joints by checking continuity on either side of the board? Or are there issues that wouldn't be detected with this test?
I was not using a dummy load; I was using my multi-band HF antenna that should have low enough SWR on 20m. (I am aware this is generally considered bad practice; I don't have a good dummy load at my test bench, only an old ATU with an internal dummy load that is annoying to use. Clearly I should have gotten the QRP Labs dummy load kit along with the QCX+...) I'll re-run the RF power test with the dummy load and see if the numbers change substantially. I believe I correctly set the radio for 20m operation, but I will check again.
Ron, I will do those measurements tonight and reply here with the results. I did do the alignment procedures. The bandpass filter alignment tone is audible, but much quieter than the manual led me to expect. (I did not have to take my headphones off during the test.) The I/Q balance and high and low phase alignments do not seem very responsive to changes in the volume knob (or, for that matter, to turns of the screw on the variable resistors). After watching one of your YouTube videos about the QCX+, I tested the resistance across the three terminals of the volume pot; they seem to be correct.
One other piece of information that might be relevant is that I initially soldered the LCD screen to the front plate using the wrong nylon spacers, and so had to de-solder it, remove it, and resolder it. I used a plunger-type desoldering tool to remove the solder, but to remove the LCD and its pin headers from the plate I had to apply a good amount of force. After doing this, I found some brown material on the pins. Is it possible I damaged the front plate PCB contacts by doing this? Would this damage be detectable and/or fixable?
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William C Brown
Gordon Young
Ronald Taylor