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Re: QMX RF sweeps
Karl, there is one more fix for you to make. Refer to?
the section Low 20m output power on early QMX builds Capacitors C525 and C516 values incorrectly swapped in the 1.00e build manual. These are the two capacitors next to the PTT port. I don't know that these will have any affect on your RF sweep graphs, but if you haven't already performed the swap, power output will be low, as stated in the troubleshooting guide. ? |
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Re: QMX Failure Discovered...and new problem
Dan,
When you have IC403 removed, check the voltage at the junction of R401 and R402, in both receive and transmit. It should be 2.5V in both cases. If you have a short at one of the bandswitch capacitors, it could go substantially higher in Receive and then trigger a latchup melt-down of the chip. The energy to produce this failure may have come from the 5 Volt supply. You seem to doubt that, and that is legit. It also might have come in from the clock generator, but that seems to be working, as you can transmit power. The remaining possibility is that the transmitter itself has fried that chip, and probably the mux chip ahead of it , too, or that a latch up as described above has happened. These scenarios seem unlikely but cannot be discarded. JZ KJ4A On Fri, Aug 18, 2023 at 5:01?AM Daniel Walter via groups.io <nm3a@...> wrote:
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Re: Fldigi and QMX successful???
开云体育Indeed that sounds like the QMX issue I see. However it does not happen on the QDX, ONLY on the QMX.?TRY reverting to firmware 006 and see if it fixes it. If so then you have exactly what I see with any mode with fldigi. 73, Cliff, AE5ZA
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Re: QMX Poor contrast with backlight on
I found the culprit! I had the screw securing the corner power supply board too tight, which caused the body of inductor L101 to contact pin #3 on the LCD board. Backing off on this screw just a little bit yielded enough clearance to put things right! Next time I remove the entire unit from the case, I'll flatten the solder hill on pin#3 and/or put a bit of kapton tape between L101 and pin#3. Unfortunately, I misplaced my kapton tape a couple weeks before my QMX build, but until then all seems good.
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Re: #qdx Middle band QDX 30m - 15m
#qdx
Hello Reiner,
Did you use all the values of the low band LP filter 20/30 for HB-QDX?? Were you able to look at the harmonics from this modification?? I did not make any changes to my HB lpf and the second harmonic did not meet FCC requirements on 30m.? I have been toying with changing out the filter, but wasn't sure it was worth the effort. .Andy W3SW |
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Re: Fldigi and QMX successful???
This looks very similar to the issue with FT8CN?/g/QRPLabs/topic/100738548#107806
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Re: QMX and FT8CN audio issue - strange issue
I'm away from my QMX for a few days. I wonder if someone could try reverting to firmware 1.0.6 as mentioned here?/g/QRPLabs/topic/100771166?p=Created,,,20,2,0,0
The author of that thread claims that Fldigi worked until he updated the firmware from 1.0.6. Then it started losing audio on the second transmission. Sounds like our issue.? 73, Mike KK7ER? |
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Re: Fldigi and QMX successful???
Wow, the description of failing on the second transmission sounds suspiciously like the FT8CN issue here:??/g/QRPLabs/topic/100738548
It is probably the same problem. Sounds like we need Hans to sort it out. 73, Mike KK7ER? |
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Re: QMX #146 is toast
g4edg
Thanks Hans
Ive just sent you a ticket describing the fault in more detail...think we must have been typing at the same time. One curious thing Ive just noticed is that when testing the 4 pin connector to the LCD board, is that if I touch with my finger the LED pin i.e. the one that connects to the gate of FET switching the LED on and off, the LED will go out, and slowly come back on again, which seems to suggest the LED pin is not connected to anything...just flapping in the wind. The LCD is switching on just because VCC is there.? LED is connected to the processor OK 73 Steve G4EDG |
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Re: I completed the assembly of the new QMX
GIUSEPPE
the red dots give me a short while the blue dots are ok, I don't know what to do. Giuseppe iu8eun Il Ven 18 Ago 2023, 16:15 GIUSEPPE via <iw8rsb=[email protected]> ha scritto:
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Re: QMX Part Missing
Hi Jim ? OMG! Sorry Hans - I thought you had an assistant (or two) handling those things for you. OK, QRX’ing - back to using my 20 meter QCX mini for a while. ? I should have. I wish I had. But... :-(? Anyway I got to your ticket now and my colleagues are handling sending you the missing part, my apologies. 73 Hans G0UPL |
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Re: I completed the assembly of the new QMX
GIUSEPPE
I tested at this moment with the DVM in the points marked in blue on the photo and it doesn't bring any short circuit.? Should I check somewhere else that there isn't a short before powering the QMX????? Thank you Giuseppe iu8eun Il Ven 18 Ago 2023, 11:10 GIUSEPPE via <iw8rsb=[email protected]> ha scritto:
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Re: QMX and FT8CN audio issue - strange issue
Same here too. The phone is a OnePlus 9 PRO. I tried several different audio settings, with the same result, first TX with RF out, second and subsequent periods no RF.?
A friend of mine has the same problem with his QMX. He tried his? with several different android phones and tablets with no luck. The only common factor being that I built both QMXs, at least that doesn't appear to be the issue. Any ideas welcome. 73 Colin |
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Re: QMX Part Missing
Hello Jim The only staff that reads the helpdesk tickets is ME... And I was on a little family vacation, I got back to QRP Labs office yesterday (Thursday) morning... so am still catching up on tickets... I am to be caught up TODAY... please QRX... 73 Hans G0UPL On Fri, Aug 18, 2023 at 4:53?PM Jim Bennett / K7TXA via <w6jhb=[email protected]> wrote: Hans - any status update on getting this core shipped out? Haven’t heard anything from your staff about it via the help ticket I submitted a week ago.? |
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Re: QMX #146 is toast
Hi Steve I am still catching?up on emails, my apologies if this has already been mentioned or dealt with.? The row of blocks on the LCD indicates that the LCD is powered, but it has not received any commands from the processor. If the display backlight is on, and you see the row of blocks, then this means that the microcontroller has correctly booted up the 3.3V SMPS and the 5V SMPS, so now the LCD has power; it has switched on the LCD backlight, and attempted to write to the LCD.? Normally if you got this far, it means the microcontroller is fine, but for some reason, the microcontroller is not communicating its commands to the LCD module; this is normally due to a connection issue on the signals between microcontroller and LCD. The usual suspects: dry joint, short to ground or adjacent signals, etc. 73 Hans G0UPL On Wed, Aug 16, 2023 at 7:49?PM g4edg via <G4edg=[email protected]> wrote: Hello Jack |
Karl
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