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Re: QMX and QMX+ won't boot.
On Sat, Jun 22, 2024 at 04:19 PM, Niels Jalling wrote:
All the smps-boards was tested and working in a rev.1 QMX.Niels, so you produced the same failur in both, but where??? Or did you use for both the same power cable, maybe a broken one? When pressing the poweron they both try to draw more than 1A at 8.8VIf not the cable please limit the current to around 250 mA for more tests. But before testing voltages check resistance from VDD to GND and VCC to GND with all the subboards removed from the mainboard. The linked document contains a link to a sketch to find the signals on the QMX. For QMX+ the signals are marked in the assembly manual. All these values should be around 10 kOhm or more. If only a few ohms something is wrong related to the VDD rail and / or the VCC rail. Please read this QRP Labs Wiki document about the start, section "switch on power". There you find information about some signals and voltages to search for the problem. 73, Ludwig |
L506 Winding Gap Improves Filter Sweeps
I just finished building my second QMX+ and the 160m filter sweep had rather ugly oscillations on it.? L506 in the 160m filter has so many windings that the start and end windings had butted against each other likely adding some parasitic capacitance in parallel.? I found that by creating a small gap between the start and end winding the sweep greatly improved.? This also improved the sweeps on almost all other bands although to a lesser degree.? I went back to my first QMX+ (which did not have ugly oscillations on the 160m sweep) and added the gap and also noticed improvement in the sweeps on almost all bands.? Has anyone else experienced this?
Andy KY4DF |
Re: QMX stopped transmitting
On Sat, Jun 22, 2024 at 10:39 AM, luigi vkw wrote:
What I have noticed is that the Voltage on transmitter is only 0.4 V.Luigi, TX voltage 0.4 V is for not transmitting, it's ok. But voltage for transmitting around 5.x V is a bit low compared to the supply voltage. Maybe to much current is drained from the PA? 1. So please show current for all the three reported bands while transmitting or something is wrong in the supply of the PA. 2. Please check the solder joints to connect L502. 3. Please check voltages at S, G and D of Q507 when transmitting. 4. Did you measure the output by an external meter? If not could you do this? 5. Please check the solder joints to connect T501 and T507. 73, Ludwig |
Re: QMX+ dev board question
Ham Radio
Jim and Hans I even used APL - extremely cryptic (but powerful and totally unmaintainable)? The choice of Basic is excellent and mere mortals can figure out what the code is doing. -- |
Re: QMX+ failed with power issues on first power up
Enjoy the FD weekend Mark! We will hit it again when you rest up. JZ On Sat, Jun 22, 2024, 3:21?PM w8gu via <w8gu=arrl.net@groups.io> wrote: Thank you.? Time for me to walk away for a while.? Must have entered the numbers in the calculator wrong.? |
Re: QMX+ failed with power issues on first power up
Thank you.? Time for me to walk away for a while.? Must have entered the numbers in the calculator wrong.?
Time to go to field day anyway.? Thank you for your help! Will go back and look at power supply on the oscilloscope tomorrow morning.? ?If things look iffy, I may just order new power supply boards.? I have been looking to put in an order for the GPS module anyway. |
Re: QMX goes into SWR protection mode during WSPR transmission
Hi Bruce,
thanks for the reply! I do not have a CMC choke on the antenna feed at this time (need to build one first). Transmitting into the dummy load seems to be working fine. SWR shows 1.3 and external power meter shows 4W. LPF sweep looks perfect. When transmitting into the real antenna (10m J-Pole vertical), SWR shows 1.6 and the external power meter shows 4W also. I'll try with a CMC choke and see what happens. 73, Andreas |
Re: Antenna tuner companion for QMX?
#qmx
Did you build the pocket tuner? If yes, would you be willing to share your experience with it?
73, Peter HB9EBE |
Re: QMX+ failed with power issues on first power up
Mark, I calculate? i=e/r = .042/1.25 = 0.0336A = 33.6 mA which is altogether reasonable. JZ On Sat, Jun 22, 2024 at 3:01?PM w8gu via <w8gu=arrl.net@groups.io> wrote: L201 measures 1.3 ohms on my Fluke. |
Re: QMX+ failed with power issues on first power up
L201 measures 1.3 ohms on my Fluke.
My old Kiethley measures 1.2 ohm.? Not sure which to believe. Voltage .042 vdc 350 mA Datasheet says 5351 is 33 mA typical.? We are getting 10x that. Based on this, the problem is most likely in the 5351, IC202, or the TXCO (or, of course, in something that is driven by one of their outputs). (kind of makes me wonder how hot the hidden components under the 3.3 volt power supply are getting.? Thinking about making a short temporary extension cable to run the system with the 3.3 volt power supply set off to the side) |
Re: QMX+ failed with power issues on first power up
I think that is the right interpretation, Mark. JZ On Sat, Jun 22, 2024 at 2:06?PM w8gu via <w8gu=arrl.net@groups.io> wrote: So if the decision on when to jump from linear to switching is made based on the 5 volt output, and if the 5 volt output is actually 5 volts, but if the 3.3 volt output is actually 3 volts (10% low), then the ADC in the microprocessor is probably using the 3.3v as a reference and saying the 5volt output is 5% high (the screen shows 5.54) and therefore not going over to switching mode. |
Re: QMX+ dev board question
开云体育For sure - absolutely nothing wrong with Basic. My programming career started out in the 60’s with RPG and then COBOL and IBM Assembly language. I’ve looked at C++ and wonder how the developers ever came up with a command syntax like that. In recent years I started using XOJO here at home - it is a resurrected version of Basic, and the command structure and syntax of Basic make life real easy for beginners and pros alike. Good choice, Hans!Jim
--
Jim / K7TXA Eagle, ID SKCC 10447T BUG 301 |
QLG3 Altitude Units
After a few hours troubleshooting why my QLG3 was not working (there's a separate thread on that adventure) I was in the GPS viewer watching it latch onto the satellites when I noticed that my QTH had suddenly gone from 2,600 feet ASL to 790 meters. Thought the GPS was whacky, then I realized that the number showing is in meters. Kinda threw me for a loop, as my older QLG2 & QRP Labs Clock gave me a display in feet. :-)
Any way that the GPS viewer can be changed to show both units? -- Jim / K7TXA Eagle, ID SKCC 10447T BUG 301 |
Re: QMX+ failed with power issues on first power up
So if the decision on when to jump from linear to switching is made based on the 5 volt output, and if the 5 volt output is actually 5 volts, but if the 3.3 volt output is actually 3 volts (10% low), then the ADC in the microprocessor is probably using the 3.3v as a reference and saying the 5volt output is 5% high (the screen shows 5.54) and therefore not going over to switching mode.
That also explains the 8.1 volts on the screen when I put 7.5 volts in. That makes me a lot happier that the microprocessor is still OK. |
Re: QMX+ - Another One Comes To Life!
This one is resolved - mostly. It turns out that when the CR2032 battery is inserted into its holder, the connectors on the right side (the minus side) short out against the positive part of the battery. I've looked at this rather closely under my magnifiers and for the life of me I cannot see how this holder ever can work as designed. So, either I've got a defective battery holder or there is a design flaw in this thing. I was able to circumvent the problem by placing a small (very small) piece of tape on the edge of the battery. Thus, when it is inserted into the holder, the two little prongs still contact the minus side of the battery, but the base of those pins no longer come in contact with the slightly larger positive part of the battery.
Has anyone else come across this situation? Wondering if Hans has followed this thread...? -- Jim / K7TXA Eagle, ID SKCC 10447T BUG 301 |
Re: QMX+ failed with power issues on first power up
The system does come up in linear mode initially.? LIN_REG_EN is an output of the MCU. It disconnects the linear regulator when the MCU decides the SMPS supply voltages are ready. IIRC the MCU monitors ADC_5V to make that decision. The ADC_3V3 signal is what is displayed as the 3.3V SMPS output. JZ On Sat, Jun 22, 2024 at 1:27?PM w8gu via <w8gu=arrl.net@groups.io> wrote: I do not really understand the enabling of the linear versus switching 3.3. |
Re: QMX+ failed with power issues on first power up
I do not really understand the enabling of the linear versus switching 3.3.
Does the system come up in linear initially and get moved to switching by the microprocessor? Is LIN_REG_EN an output of the microprocessor? If so, what does the microprocessor use to determine that it is time to go to switching mode? Is the 3.3 voltage on the hardware diagnostics the voltage of the output of the switching mode 3.3 (i.e., ADC_5V)? ================= still on my to-do list is - checking the resistance/voltage on L201 - Looking at the outputs CLK0/1/2 on a scope. Not likely to get to these until tomorrow.? Planning on visiting our club's field day operations. |
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