Re: USB reconnection to QMX+ after PC restart
On 29/01/2025 22:34, Carl Willis (KF4KIG) via groups.io wrote: Regarding the relay idea, how would this work?? Interrupting supply power to the QMX+ probably just turns it off, in which state it remains unless the power button is pressed (is this correct?). Carl, I was thinking of a QDX which does come up instantly. I'm not sure about the QDM. Does it just need the power button press? As I said, I've not thought about the details. A little routine run at startup could trigger some circuitry, maybe from a COM port. Jon, I had thought it was a problem with Windows but I'm sure Linux users have reported it as well. I have it with a QDX and a RPi. 73 Alan G4ZFQ
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Re: 12V Battery 2Ah + Charger 2.4A
That's an extremely good price. Here in Austrian Lidl they cost 25� each and the electronics doesn't seem so dumb (has cell balancing and all). At this price I wouldn't think twice I guess.?
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Re: Factory assembled QMX Encoder not working
First thing to try is to increase the space between the button and the chassis by setting it higher. Happened to me that the button came down, in particular if the push is a bit pushy, and then was too low to trigger the push contact.
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73 Peter
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Re: Disconnection while transmitting, something in my USB cable?
#help
#qmx
Since I'm still waiting patiently for my QMX+, I can't say anything specific to that device - but I did have similar problems with other transceivers: Everything fine while receiving, no problems when using the TRX standalone, but weird things happen on the PC, when transmitting while USB is connected. Basically, the effect has always been, that the USB device did not not behave as expected anymore, disconnects, throws errors, does random other things. The errors and disconnects could be observed with the dmesg -w command in Linux. I even had problems with some other wired USB-devices, like unwanted keystrokes from my keyboard, mouse disconnecting, transceiver resetting, problems in the wired-network-stack, disconnecting DSL, to name but a few. All of them presumably related to unwanted RF in the shack (e.g. introduced? by an ungrounded and badly tuned endfed antenna). The problems were repeatable when using more power and did not occur that often when using QRP. SSB made less problems than FT-8.
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I found the following measures helpful:
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* Proper HF-grounding of the TRX
* Using a properly tuned antenna / minimizing unwanted RF
* HF-grounding the balun on my endfed antenna
* Not routing the antenna-cable and the USB-cable in parallel. Not having loops or knots the USB cable. Not having RF components in close proximity to USB cables.
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* Using an USB-cable as short as possible (50 cm at the moment in my case).
* Use of an USB 2.0 cable instead of a 3.0 cable (not the blue ones, but the black or white ones). The USB-A type cables are backwards-compatible, but I found the 2.0 cables working much more reliably than the 3.0 cables. Maybe I just picked some special-case, though.
* Use of a high-quality cable. Not necessary an expensive one, but one with a good (= thick, dense) shielding. I did not have good experiences with the coiled USB-cables from Digirig, by the way. Those are great cables and work very well in my portable UHF/VHF settings, but were not the best for connecting an HF-TRX to my PC.
* Using ferrite chokes on both ends of the USB cable (without coiling the cable). Don't do that on 3.0 / USB-Connections - but absolutely ok on 2.0 Hi-Speed connections.?
* Galvanically isolate the PC from the TRX. That's easier said than done, because the ground is an essential part of the USB-protocol. Lifting the shield or connecting it to ground made things worse in my case. I now use an USB Isolator device. I did have no luck with the cheap usb-isolators, though and ended up with an (absolutely not cheap) Hi-Speed-Isolator from Intona. There are much cheaper Hi-Speed Isolators on the marked now, but I did not have the chance to test those yet. Those isolators may introduce a field of problems on its own, especially when used to isolate multiple USB-devices, but at the end, I found them very helpful. I did have good results, too isolating the serial connection using optocouplers (before converting them to USB) and audio transformers on the audio signals. Both do cost only a few cents and do provide full galvanic isolation. The whole idea behind this measure is, that no RF that may be on the TRX-ground can reach the PC-ground / shield.
* Also some USB-Hubs or even some specific USB-connections on the PC did introduce problems. Trying different components and avoiding some specific connectors on the PC helped.?
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Maybe not every bulletpoint is strictly neccesary. I did get away with some wild setups. I had great success for a long time with a 5 meter long cheap cable without chokes, without galvanic isolation and coiled like a mess. On the other hand, I had big problems, even with a short, choked cable but an inproper tuned endfed antenna. I never hat big problems when using a well-tuned dipole. So: That's just my observations and what I did to solve the problems. If, from time to time, any similar problem arises in my portable setup: I check the TRX-grounding, route the uSB-cable as direct as possible, make sure an USB-Isolator is used and the antenna is properly tuned. That measures do solve those problems for me reliably. And: Maybe I just have been lucky, but I never did any damage to my PC so far - knocking on wood :-)
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Yours, Joe, DJ0CHE
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Can you include some more information like your location and is the QDX assembled and working?
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Factory assembled QMX Encoder not working
I received my assembled QMX a couple of days ago. Out of the box, the encoder intermittently woked a couple of times changing tuning steps and now does not work on the functions that require pushing down on the shaft, specifically tuning step change, messages, or factory reset. It does work on those functions done by rotating the shaft. This occured after only a couple of step changes.
Has anyone else experienced this problem?
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Re: QMX+ suddenly SWR sweep stops
Hi Bruce,
sorry, I have seen your email just now.
It's not mentioned in any document!
Now, with your and Stan's describtion I fully agree that its a realy bad idea ...
Thanks a lot for explaining it! I'll change my setup, and won't do it again that way ;-)
Cheers,
Torsten
Am 29.01.2025 um 10:02 schrieb Bruce Akhurst:
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Where was this idea mentioned in the instructions ?
ATUs aren’t very bright. ?They initially offer a wild range of match solutions to spot a good one some of which will look
like a horrible SWR at the transmitter
Along with the horrible SWR may be high CMC which can cause damage too
Running such tests at the lowest TX output power the tuner will accept is a good plan- ? Doing it via a 3dB pad is good too
--
vy 73 de Torsten | DB2TE
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Re: QMX+ build ... don't do what I just did
I would use braid and a bit of extra flux.? I just did this on? some low pass boards for a U3S.? I did add a bit of solder to the holes so the braid had good contact.? On one board I managed to reverse the c1/c4 with c2/c3.? I was able to remove the capacitors using ChipQuick low melt solder, then filled the holes with 60/40 ( don't leave ChipQuik on a board as it is brittle) then cleaned them out with braid.?
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Re: Interesting source of chirps
Basically space is a huge klystron.
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On Jan 29, 2025, at 21:20, ta2rx bekir via groups.io <ta2rx.bekir@...> wrote:
? I do not know how effective they are on our radios but I found this info interesting:
73! de Bekir TA2RX
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Interesting source of chirps
I do not know how effective they are on our radios but I found this info interesting:
73! de Bekir TA2RX
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Re: USB reconnection to QMX+ after PC restart
I would think that the USB interface would detect both connects and disconnects. When you power cycle the computer, the connection goes away and this should be detected. When the computer restarts, the USB interface should detect this and begin to attempt enumeration.
All USB devices I’ve ever used are automatically detected at each reboot of the computer. This seems like a solved problem so what am I missing? Could this be due to the lack of a dedicated USB interface chip?
Tony
On Wed, Jan 29, 2025 at 4:34?PM Carl Willis (KF4KIG) via <carl.willis= [email protected]> wrote:
I would think that if the QMX+ firmware can execute a bootstrapping power-on sequence, it could trivially be programmed to restart itself, but indeed that is beyond my level of familiarity.
Regarding the relay idea, how would this work?? Interrupting supply power to the QMX+ probably just turns it off, in which state it remains unless the power button is pressed (is this correct?).
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Re: USB reconnection to QMX+ after PC restart
I don't have any problem rebooting my Raspberry Pi remotely and the QMX+ retains connectivity ...?
I use X11 forwarding to XQuartz on my MacBookAIr to run WSJTX on the Raspberry Pi but manipulate it similar?to remote desktop.
Occasionally?I have to reboot and never had an issue with the QMX+ not being seen.? ?Likely a difference between PC and Linux drivers On Wed, Jan 29, 2025 at 5:34?PM Carl Willis (KF4KIG) via <carl.willis= [email protected]> wrote:
I would think that if the QMX+ firmware can execute a bootstrapping power-on sequence, it could trivially be programmed to restart itself, but indeed that is beyond my level of familiarity.
Regarding the relay idea, how would this work?? Interrupting supply power to the QMX+ probably just turns it off, in which state it remains unless the power button is pressed (is this correct?).
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Re: 12V Battery 2Ah + Charger 2.4A
Agreed, if you can, go for the most moderate charging rate on batteries as possible, unless you have some absolute need for them to be completely charged in 1-2-3 hours. The batteries will appreciate the lower charge rate, there will be less heating and the life-expectancy of the cells will increase because you are not flogging the chemistry about.
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I was badly burned by the misapplication of lithium batteries in a circuit where there was a lead-acid string prior to modification (not my modification). The cells decided to spontaneously combust and I (foolishly) felt the need to yank the batteries out to save the device.
--
Tisha Hayes
AA4HA
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Re: Disconnection while transmitting, something in my USB cable?
#help
#qmx
The impedance of a toroid is the square of the number of turns you make through the toroid.
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So impedance, the resistance to AC signals.. doubles with two turns, quadruples with three turns.. and so on.
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Yes, you get 'some impedance from going through a toroid once, you get much more impedance if you can take that wire and go through twice, or three, or four times.
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That impedance, (resistance to the flow of AC) will attenuate down signals (going both ways) through the conductor. Your radio becomes isolated from computer noise, Your computer becomes isolated from radio noise (and RF power due to a mismatched antenna system.
You also need to remember that the 'mix' of the ferrite core is going to be frequency-range-deterministic. Some are better at lower frequencies, other at higher (+VHF)
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I always thought it a little wasteful of just doing a single pass but then sticking four or five cores in series. Take advantage of any room through the core and put as many turns as you can through it. That is one advantage of snap-on cores, you can usually get 2-3 turns through even a small core.
--
Tisha Hayes
AA4HA
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Re: QMX+ build ... don't do what I just did
Bruce,
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I'm just a little behind you on my build, I just soldered L502 in. As far as I can see, those LPF holes don't have anything soldered to them, so you are all right.
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Joel
N6ALT
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Re: USB reconnection to QMX+ after PC restart
I would think that if the QMX+ firmware can execute a bootstrapping power-on sequence, it could trivially be programmed to restart itself, but indeed that is beyond my level of familiarity.
Regarding the relay idea, how would this work?? Interrupting supply power to the QMX+ probably just turns it off, in which state it remains unless the power button is pressed (is this correct?).
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QMX+ power & transmit current vs input voltage plots
I characterized my recently completed QMX+ by recording?
transmit current vs band and input voltage - 7, 8, 9, 10, 11, 12 v (the/my QMX+ refuses to transmit below about 6.75v )
receive current was about 170ma at 7v input to about 110ma at 12v.
i also recorded transmit power at these same configurations.
two plots are attached.
160m exceeds 6W at 11v input and 7W at 12v
30 and 80 exceed 6w at 12v
maximum transmit current observed was 1.02A
Should I avoid using configurations that exceed 5W out, or is it the transmit current that is the destructive parameter?
thanks in advance
lars/KN5UTE?
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QDX and Japanese Band Limits
I checked again today my QDX Hi Band, PCB rev.5, firmware v1_10 and the problem /g/QRPLabs/message/103640 is still there: transmission is disabled on all bands (20M to 10M) if "Japanese Band Limits" is "ENABLE". If it is "DISABLE" no problem all bands will transmit.
73 - Pierre - FK8IH
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Alan, fldigi v.4.2.06 is installed in c:/Programs and the fldigi.files is installed in my user forlder.
73 - Pierre - FK8IH
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Re: USB reconnection to QMX+ after PC restart
On 29/01/2025 20:38, Carl Willis (KF4KIG) via groups.io wrote: Whenever I reboot the mini PC, with the QMX+ remaining powered, I lose USB connectivity to the QMX+. Carl, Unfortunately this is normal. The QDX/QMX will only enumerate once then require a power cycle. Hans knows this but does not know how to correct it. A possibility is to trigger a relay when the computer starts up. I'm sure it could be done but to my knowledge this has not been discussed. 73 Alan G4ZFQ
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Peter HB9EBE
Tom Clifton
Tisha Hayes, AA4HA
Joel Caulkins/N6ALT
Carl Willis (KF4KIG)
Pierre - FK8IH