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QMX with QLG2 GPS
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I have used a QLG1 with my QCX+ and minis for WSPR and with my shack clock. I love QRP Labs.
I recently assembled a QMX and I have an unbuilt kit for the QLG2. I see in the manual that the QMX does not have a 5V output to power the QLG2. I want to take both on SOTA outings (which means I want to carry as little weight and bulk as possible). What are your thoughts on the best options for a portable 5V power supply for the QLG2? -- 73 Michael N6QP Up in Thin R |
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Hello Rob I specifically did NOT make provision for 5V for powering a GPS for two reasons: 1) On the QCX+ and QCX-mini,?+5V is available at the tip of the PTT output connector. This was specifically designed to be compatible with the 50W PA kit which was designed to suit the QCX. It was probably a mistake to make the QCX PTT output a?+5V-active signal, which is not the accepted ham radio equipment convention, where a grounded PTT in/out is normal. But it's a mistake which is made and done and hard to back out of now.? However QDX has the possibility for both an active +5V output to suit the 50W PA, and a grounded output to suit conventional amplifiers. These are on the tip and the ring respectively. This way the QDX can be used with either. It's important to make it usable with other amplifiers because?the 50W PA kit is single band (unless modified), whereas QDX is multi-band.? Since QMX is also multi-band and closer really electrically to QDX, than it is to QCX-mini, I chose to go with the QDX style PTT output, not the QCX+/QCX-mini style. Therefore there is no connector available to be able to provide a?+5V output suitable for powering a QLG2.? 2) The second reason is that if I allow a?+5V connection to the outside world, then I have to provide specifications for it; for example maybe I would have to say, the?+5V output from the?+5V SMPS would need to be limited to 50mA. And how would I specify the ripple under all circumstances, and guarantee that it would suit a QLG2, and not be noisy for a QLG2, or perhaps require filtering? How would I guarantee that nothing would kill the 5V SMPS if you shorted something by mistake, or otherwise abused it?? Right now, the?+5V SMPS is inside QMX, and is powering only QMX. The microcontroller knows how much current the QMX requires on its?+5V rail, and it knows the applied supply voltage to QMX (by measurement), and it has a built-in performance curve, in other words a graph of PWM duty cycle vs supply voltage; from that it can calculate with a suitable safety margin (I currently use 15%) a maximum duty cycle and it can prevent anything going higher than that.? This self-contained feature of the load on the SMPS, lets me apply a number of self-protection mechanisms which make it able to withstand many kinds of faults; if there is a cold joint on any pin of any of the SMPS connections, it will not cause a failure that over-volts the 3.3V or 5V rails enough to kill the components supplied by those rails. Of course you can't recklessly short or solder-bridge anything to anything and expect to always survive, but you never can anyway on any board.? Do you see?? A 7805 voltage regulator like on QCX-series transceivers, is one thing. And probably even fine, a SMPS buck converter general purpose board that you could use to power things (though the switching noise can be a problem).? But QMX does things in WILD ways, for performance (low receive current, without noise) and cost, and in order to be able to tame the wildness, it has to be well in control of everything! It's WILD for the single microcontroller of QMX, to be the control loop for its own 3.3V supply and the 5V supply and PIN diode supply, all being switched mode buck converters for the desired low receive current consumption.? Yet, the wildness is adequately and elegantly tamed, by all the hardware and firmware failsafe mechanisms that I put in. All the PWM and control signals to the SMPS boards are pulled down or up by resistors so that in the absence of microcontroller CONTROL, everything is safe. In the event of cold solder joints causing signal disconnections in one or more pins, everything is safe. The firmware runs the PWM in timer peripherals that are independent of the main program execution. The control loop runs in the highest priority interrupt. If the code hangs, it never kills the system by letting the PWM control loop go off on its own. If it crashes and resets, then the SMPS boards are also in a safe state due to the hardware safeguards. Believe me, I know! Because when I do code development, of course I make many mistakes, which crash the program or hang it. But it never kills the system. I've been doing all my code development, all my various hardware testing and changes, incident Turkish coffee, and even the harsh input voltage step (see ), all on the same QMX, that never dies. I could not do SOME of those safeguards, if the 5V rail was opened up to external use. Right now if you connected the QLG2 power supply to the?+5V pin of the SMPS, with a wire (because I intentionally provided no connector pin), then it would not work because it would draw more current and this would trigger the protection mechanism on max PWM duty cycle vs supply voltage.? Sure, I could add a configuration parameter, for example, that disables the max-PWM check internal model. Then it would work and supply the 30-40-50mA or whatever it is the QLG2 takes. This would be well within the capability of the 5V SMPS board. But: a) you'd lose some important safeguards and b) I don't know if the ripple and noise would be OK for the QLG2 or would need more filtering.? I'd suggest rather than talking me into providing a "disable 5V SMPS safeguards" parameter, you'd be better off getting?+5V for the QLG2 from somewhere else... it's quite easy to build a 7805 in line to the QLG2 and will be much nicer :-)? 73 Hans G0UPL On Sun, Aug 20, 2023 at 4:28?PM <ha7rja@...> wrote: I have the same issue. There seems to be 5V available on plug-in PCB #1, so can that be used for powering the GPS module? |
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I'm just running my QLG2 through the USB port from a spare iPhone charger and so far it's working well.? I was hoping though to be able to leave it connected to the QCX-mini continuously for a remote and unattended CW beacon but apparently that's not possible with this design due to sharing of the same jack with the PTT function.? ?If there's a way to do this I would like to know.?? Thanks, Jerry AC5JM.
On Sunday, August 20, 2023 at 09:29:56 AM CDT, Hans Summers <hans.summers@...> wrote:
Hello Rob I specifically did NOT make provision for 5V for powering a GPS for two reasons: 1) On the QCX+ and QCX-mini,?+5V is available at the tip of the PTT output connector. This was specifically designed to be compatible with the 50W PA kit which was designed to suit the QCX. It was probably a mistake to make the QCX PTT output a?+5V-active signal, which is not the accepted ham radio equipment convention, where a grounded PTT in/out is normal. But it's a mistake which is made and done and hard to back out of now.? However QDX has the possibility for both an active +5V output to suit the 50W PA, and a grounded output to suit conventional amplifiers. These are on the tip and the ring respectively. This way the QDX can be used with either. It's important to make it usable with other amplifiers because?the 50W PA kit is single band (unless modified), whereas QDX is multi-band.? Since QMX is also multi-band and closer really electrically to QDX, than it is to QCX-mini, I chose to go with the QDX style PTT output, not the QCX+/QCX-mini style. Therefore there is no connector available to be able to provide a?+5V output suitable for powering a QLG2.? 2) The second reason is that if I allow a?+5V connection to the outside world, then I have to provide specifications for it; for example maybe I would have to say, the?+5V output from the?+5V SMPS would need to be limited to 50mA. And how would I specify the ripple under all circumstances, and guarantee that it would suit a QLG2, and not be noisy for a QLG2, or perhaps require filtering? How would I guarantee that nothing would kill the 5V SMPS if you shorted something by mistake, or otherwise abused it?? Right now, the?+5V SMPS is inside QMX, and is powering only QMX. The microcontroller knows how much current the QMX requires on its?+5V rail, and it knows the applied supply voltage to QMX (by measurement), and it has a built-in performance curve, in other words a graph of PWM duty cycle vs supply voltage; from that it can calculate with a suitable safety margin (I currently use 15%) a maximum duty cycle and it can prevent anything going higher than that.? This self-contained feature of the load on the SMPS, lets me apply a number of self-protection mechanisms which make it able to withstand many kinds of faults; if there is a cold joint on any pin of any of the SMPS connections, it will not cause a failure that over-volts the 3.3V or 5V rails enough to kill the components supplied by those rails. Of course you can't recklessly short or solder-bridge anything to anything and expect to always survive, but you never can anyway on any board.? Do you see?? A 7805 voltage regulator like on QCX-series transceivers, is one thing. And probably even fine, a SMPS buck converter general purpose board that you could use to power things (though the switching noise can be a problem).? But QMX does things in WILD ways, for performance (low receive current, without noise) and cost, and in order to be able to tame the wildness, it has to be well in control of everything! It's WILD for the single microcontroller of QMX, to be the control loop for its own 3.3V supply and the 5V supply and PIN diode supply, all being switched mode buck converters for the desired low receive current consumption.? Yet, the wildness is adequately and elegantly tamed, by all the hardware and firmware failsafe mechanisms that I put in. All the PWM and control signals to the SMPS boards are pulled down or up by resistors so that in the absence of microcontroller CONTROL, everything is safe. In the event of cold solder joints causing signal disconnections in one or more pins, everything is safe. The firmware runs the PWM in timer peripherals that are independent of the main program execution. The control loop runs in the highest priority interrupt. If the code hangs, it never kills the system by letting the PWM control loop go off on its own. If it crashes and resets, then the SMPS boards are also in a safe state due to the hardware safeguards. Believe me, I know! Because when I do code development, of course I make many mistakes, which crash the program or hang it. But it never kills the system. I've been doing all my code development, all my various hardware testing and changes, incident Turkish coffee, and even the harsh input voltage step (see ), all on the same QMX, that never dies. I could not do SOME of those safeguards, if the 5V rail was opened up to external use. Right now if you connected the QLG2 power supply to the?+5V pin of the SMPS, with a wire (because I intentionally provided no connector pin), then it would not work because it would draw more current and this would trigger the protection mechanism on max PWM duty cycle vs supply voltage.? Sure, I could add a configuration parameter, for example, that disables the max-PWM check internal model. Then it would work and supply the 30-40-50mA or whatever it is the QLG2 takes. This would be well within the capability of the 5V SMPS board. But: a) you'd lose some important safeguards and b) I don't know if the ripple and noise would be OK for the QLG2 or would need more filtering.? I'd suggest rather than talking me into providing a "disable 5V SMPS safeguards" parameter, you'd be better off getting?+5V for the QLG2 from somewhere else... it's quite easy to build a 7805 in line to the QLG2 and will be much nicer :-)? 73 Hans G0UPL On Sun, Aug 20, 2023 at 4:28?PM <ha7rja@...> wrote: I have the same issue. There seems to be 5V available on plug-in PCB #1, so can that be used for powering the GPS module? |
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Hi Jerry ?
The beacon?functionality (includes CW and WSPR) is exactly what QLG2 is designed for, on both the QCX-series and QMX transceivers. QMX serial data and 1pps are connected to the transceiver (QCX-series or QMX) with a 3.5mm stereo connector. It's all in the relevant manuals.? 73 Hans G0UPL |
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OK, that's encouraging.? My QCX stops transmitting following GPS synchronization until I unplug the QLG2.? I must have missed something in the programming.? I'll review the manuals again. Thanks, Jerry
On Sunday, August 20, 2023 at 10:12:00 AM CDT, Hans Summers <hans.summers@...> wrote:
Hi Jerry ?
The beacon?functionality (includes CW and WSPR) is exactly what QLG2 is designed for, on both the QCX-series and QMX transceivers. QMX serial data and 1pps are connected to the transceiver (QCX-series or QMX) with a 3.5mm stereo connector. It's all in the relevant manuals.? 73 Hans G0UPL |
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Michael, I just received a Talentcell TB1203000-USB 12V + 5VUSB battery pack, to power my QMX. Thomas Witherspoon K4SWL uses/has used this compact brick to power his QCX. I didn't even think of also powering my QLG2 with it. But indeed, it has a 12V barrel jack output AND a 5V USB A output. It's still charging, so I haven't tested it out. This little pack is exactly the same size as the QMX. It might work well for your SOTA QMX+GPS outings.
$27 Amazon |
Michael N6QP
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