Re: Debugging BS170-related issues
Well, I'm getting closer after the meltdown. Q503, Q507 and all the BS170's replaced.? Power output 0.6 watts. Drawing 350 mA from 12 volt supply. Gate voltage on the BS170's seems okay - 2.6 volts key down.? PA voltage 9.6 volts, key down. Swapped BS170's. No change.
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Where do I measure/check next ?
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Thanks and 73,
Steve, N2IC
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Re: V6 Sythesiser PCB link wire
Well it’s a lovely job. ??
Only noticed it under high magnification !?
Thanks Bruce! Mr Levent is very good at such things and after some hundreds he was getting even better! But still, I will try not to make that PCB mistake again next time...
73 Hans G0UPL
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Hi QMXies.?
As a sota enthusiast i was missing a working clock (on the QMX .. not QMX+) regardless if batteries have been removed before.
There is everything there also in QMX, but the 32kHz Q and the buffer battery.
I (carefully) released pins 6, 8, 9 of the STM32 from the PCB, soldered 3 thin wires to the elevated pins ant fixed them with epoxy glue. Then attached a 32kHz Q to 8 & 9 pin wires.
As i don't need the PTT output for sota, i removed the PTT connector, which made room for the CR2016, attached to pin 6 wire.
Settings "real time clock"? set to QMX+? RTC? and "set time"? -- voi la. Now the RTC keeps on running while QMX is in his transport box without any power attached :-)
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I have to confess, you need some skills in working with very small soldering tips under the microscope, as the pins of the STM32 are really close together. Solder bridges don't have to bring you out of concept ;-)
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:-) Wolfgang OE3WHU  
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Re: Power Failure on New Factory-Assembled QMX+
To close the subject, the problem was with me, not with the QMX+.?
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I don't know what I did last week (may have been transmitting on 10m into a 15m tuned dipole), but the rig finally would not switch on and I thought I had fried it.? A few days later Hans asked me to check voltage on receive.? Honestly!? I was sure that it wouldn't switch on.? But it did, and is working flawlessly.
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Lesson:? If you keep trying to transmit with an 'S' constantly appearing on the display, and finally the rig won't switch on, don't despair.? Give it some time, check and re-check your settings and try again.
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Tim Ei2KA
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QMX+ points A continuity check to ground question
On p25 of the Rev 3 QMX+ manual, there is a check for continuity to ground from three points A. BEFORE installing T501, when checking the three points A,? I get about 15 ohms with the DMM black lead on the ground connection, but open circuit (desired) with the? leads reversed (ie red lead on the ground connection). Is this to be expected? The 4 BS170's ARE installed.
I am troubleshooting a continuity check problem identified after having installed T501 (now removed).
Thanks
Steve AK0M
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Re: Help ID QDX Digital voltage and band option
Hello Dave,
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Dan's suggestion is good with one addition:? do the test into a 50-ohm dummy load.? Antennas can cause higher or lower power due to differences in impedance.
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73
Evan
AC9TU
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Re: ProgRock2 programming??
On 02/04/2025 14:59, cct314159 via groups.io wrote: - Even though they are "rated" for "12 volts" *don't even think about running one at that voltage:*? I'd avoid going above 10.0 volts. Yes, that reminds me. I tested with 12 volts and it certainly got a lot hotter than I expected. The ones I use are fed from 5 volts and keep cool. 73 Alan G4ZFQ
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Thank you, Ludwig. That does it. PA voltage now 0.3 instead of 10.9.
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73,
Steve, N2IC
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Re: QMX (not-plus) power issue
What did you come up with, Michael?? Did you ever get your 20m power up beyond 1.2w?
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Joshua
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Re: Tone or birdie every 500 Hz in USB mode
My guess is that DIGI mode has a wider bandwidth so more noise. This will cause AGC to cut the gain a little bit and the spurs will appear reduced.
Tony
AD0VC
toggle quoted message
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For some reason I cannot get audacity to record from the QMX.. But WSJT-X sees it fine (yes, I closed WSJT-X first before trying Audacity). So no audio recordings but another picture. Mel, mine sounds very similar to yours.
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I have confirmed that the pulsating tone noise at 1Khz was from the GPS module, as with it removed the noise at 1Khz is markedly reduced. I will run it this way in the morning and see if it is better able to decode MSK144 without that persistent pulsating
noise at 1KHz. I still see less of these noise lines in DIGI mode than in either USB or LSB, so I think there is something different with the RX audio? in DIGI that might help with USB also if I can figure out what the difference is.
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Re: V6 Sythesiser PCB link wire
Well it’s a lovely job. ??
Only noticed it under high magnification !?
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Re: SSB audio distortion #qmx #SSB Firmware beta 1_01_003 release
#qmx
#ssb
Hi Mehmet,
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Everything looks for me. I have no ideas now. I don't have a QMX+, instead, a QMX HB version and a QMX LB version. And 80m is the only band I had trouble with.
--
73, de BD8BTE
op: Lun Yang
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Steve, if your solder iron has enough power (at least 50 W but better a bit more) you may do this:
- Desolder L502.
- Apply ChipQuick low temp solder to the two pins of Q507.
- Take a bit of flux on the metal of Q507 opposite to the two pins.
- Take a blob of normal solder with your iron on this metal of Q507 and wait 5 or 8 (or 12) seconds or so until you could take Q507 away. Because of ChipQuick the heat coming through Q507 to the pins is enough to melt this solder.
- Remove all ChipQuick from the solder pads for the pins.
- Don't remove the solder from the pad for the body of Q507.
- Apply a bit flux on the solder pad for the body of Q507.
- Hold the new Q507 in place using tweezers and heat Q507 like in No. 3 and 4 until you feel Q507 is swimming on the solder.
- Remove the solder iron and hold Q507 in place until it's fixed.
- Solder the two pins.
- Solder L502.
73 Ludwig
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Re: SSB audio distortion #qmx #SSB Firmware beta 1_01_003 release
#qmx
#ssb
Hi Lun,
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The phase error plot doesnt complete for most of the bands, not just 20m. All of the plots just look random zigzags and never the same on consecutive runs. Some are just a straight lines going across the top of the screen and these seem to complete ..
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This is what I get on 20m..
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?
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No Tx
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During Tx
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Mel, M0KMD
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?
?
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Re: Help ID QDX Digital voltage and band option
Power supply voltage does not matter for RX. It only makes a difference on TX. You could try and figure out how the output transformer is wired, but that is difficult without removing it. I would suggest powering it at 9V and seeing what the power output is. If it is a 9 V unit, power should be 4-5 W on all bands. If it is a 12 V unit, power will be about 2-3 W.?
--
73, Dan? NM3A
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Re: Qmx plus rev 2 not powering up
Azgael, please check schematics for QMX+ Rev. 2 / 3 page 1.
Gate of Q101 together with LIN_REG_EN is connected via R101 to "+12V". With pressed vol-encoder and not running controller LIN_REG_EN is pulled to around the voltage at "+12V". After the controller gets VDD via IC101, starts to run and VDD is proper generated via Q109 the controller will pull LIN_REG_EN low to around 0 V.
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Checking schematics Rev. 4 for QMX you will find nearly the same things but additional R115 from LIN_REG_EN to GND, forming a voltage divider 0.5:1. This pulls LIN_REG_EN for the start only to 50% of "+12V".
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But if you would see also only 50% of "+12V" at LIN_REG_EN of your QMX+ maybe R115 is hidden somewhere in the "deep parts" of QMX+ schematics.
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73 Ludwig
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Re: Tone or birdie every 500 Hz in USB mode
For some reason I cannot get audacity to record from the QMX.. But WSJT-X sees it fine (yes, I closed WSJT-X first before trying Audacity). So no audio recordings but another picture. Mel, mine sounds very similar to yours.
?
?
I have confirmed that the pulsating tone noise at 1Khz was from the GPS module, as with it removed the noise at 1Khz is markedly reduced. I will run it this way in the morning and see if it is better able to decode MSK144 without that persistent pulsating noise at 1KHz. I still see less of these noise lines in DIGI mode than in either USB or LSB, so I think there is something different with the RX audio? in DIGI that might help with USB also if I can figure out what the difference is.
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Re: QMX+ rev 3 freezes shortly after boot
On Wed, Apr 2, 2025 at 01:24 AM, @Ludwig_DH8WN wrote:
Michael, please don't switch on your QMX+ in the moment. I will send more information later today.
73 Ludwig
RR! Will hold off on any more tests/debugging until I hear from you ?
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Re: Gibberish characters appended onto end of Message 1
I had a similar experience. After deleting and re-recording the messages, it has not re-appeared.?
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73, Dan? NM3A
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After the great BS170 meltdown on my QMX, I'm down to replacing Q507 (Q503 and the BS170's have been replaced and look good). I do not have a hot air rework station - only ChipQuik. It looks like the drain is a pad, not directly accessible with a soldering iron.? Suggestions on how to replace Q507 with the materials I have ?
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73,
Steve, N2IC
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Joshua KJ7LVZ
Bruce Akhurst
Michael Shiplet