Re: QMX working FB then shorted out. Ideas?
Jeffrey,
I'll take your word for it. I've blown the finals on the QDX and it was just low power out. I guess the QMX is different. That sure is an easier fix than some other things.
I'll just pull the finals and if it will power up then I'll know they are the issue.
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Yes. ?That is not unusual for blown finals. ?Try replacing all 4 BS170s. ?Chances are good that will fix it. ?If not it may be the driver IC needs replacement also.
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QMX: Kit build trouble, a short between A & B for Step 17 of Section 2.9
I started building QMX following the instructions carefully. I've been checking the solders in every step.
Installed the transformer T501, checking the continuity between the A points were fine as well as the continuity between the B points.
However, when I checked between A points and B points, my DMM shows about 370 KOhms.?
I guess I must have a short somewhere. :(
I've been using a digital microscope to verify solder bridges on the way, and did visual inspection, but I cannot find anything that could be shorted.
Any suggestions on how to troubleshoot this?
I am about to brute force troubleshoot by desoldering one by one while checking the continuity.
Thank you in advance.
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SMD 10k resistor, 103 replacement for QCX mini
I picked up a QCX mini, 20 m, revision 1 at a ham fest.? When building I noticed the R46 resistor was badly placed and cracked.? It looks like a factory error when placing the SMD's.? I need a replacement of the SMD 10k resister, labeled 103.? Mouser has about 20 options.? Can anyone point me to the correct SMD resistor so I can repair this kit.
Thanks,?
AB4BA
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The Q103 FET was broken In an attempt to move it, 'D403'.? I have several AOD21357 FETs that appear to have virtually identical specifications.? Can they be used as an acceptable substitute for Q103?? Hopefully someone other than Hans will answer, he is surely too busy to bother with this question.?
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Re: QMX: Kit Build complete - My observations
Finished, in the box and working!
--
73
Karl
KI4ZUQ
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Re: QMX successful so far - power chase
Yesterday I activated a POTA and took part in the Skeeter Hunt with 10 contacts in 7 States and the RBN reporting me 3750 miles away using my QCX-Mini and a homebrew 20m (46”) Mag mount. ?My power after the tuner was just 3.5w or so.
My point is....... don’t sweat trying to squeeze out the last mW, it’s the ears on the other end and YOUR antenna that is most important.
JOHN KK4ITX?
The QCX-Mini is a great machine and I bet that the QMX is better in many ways too !!
John
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On Aug 28, 2023, at 20:20, Sandy < mac3iii@...> wrote: I agree with other commenters. Quit while you are ahead.... Or buy another kit, build it, and tweak/modify to the max! That way you will always have one that works :) Sandy KB3EOF
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Re: QMX working FB then shorted out. Ideas?
Yes. ?That is not unusual for blown finals. ?Try replacing all 4 BS170s. ?Chances are good that will fix it. ?If not it may be the driver IC needs replacement also.
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Re: PTT over CAT in WSJT-X no function, does not transmit in FT8
Set the "power" slider in WSJT-X all the way up. In the digital mode the QMX is not modulating SSB. Its doing true FSK, based on the tones on the input. If they're below the threshold to decode, there's no output.
73 de K9ID
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On 8/28/2023 2:46 PM, Alan G4ZFQ wrote: On 28/08/2023 17:25, Reinhard Gr?nz via groups.io wrote:
My device still has a problem. It does not broadcast in FT8. If I tap the PTT button in the configuration of WSJT-X, it lights up red. There is no signal on the antenna when transmitting. Reinhard,
Possibly PC configuration? /g/QRPLabs/topic/100624101#108489
73 Alan G4ZFQ
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Re: QMX successful so far - power chase
I agree with other commenters. Quit while you are ahead.... Or buy another kit, build it, and tweak/modify to the max! That way you will always have one that works :) Sandy KB3EOF
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Re: QMX working FB then shorted out. Ideas?
Thanks Paul. I realize that they may be blown, but from my recollection they didn't continue shorted. Low power out was the usual symptom IIRC. This is a complete short immediately on power on.
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Most likely culprits are going to be the BS170's, and possibly
IC503, from other reports. Paul -- AI7JR
On 8/28/23 15:32, Cliff wrote:
Well, guys, I'm up a creek it seems here. I'm an old guy, raised on Tubes, and don't really understand Mosfets and the schematics for the QMX are hard for me to follow.
Some suggestions to trace the issue here would be much appreciated.
I built this QMX about 3 1/2 months ago. It's been working FB with firmware 006 ever since. This morning I was using it and transmitted accidentally with no antenna attached. It's happened before with no consequences, but this time something shorted out big time. The power supply went into current limiting at 1 amp with the voltage dropped to 6 volts. Powered off with a BIG SIGH!
Opened it up and just a little smell of hot electronics, but not the usual burnt smell. Inspecting all the boards and nothing obviously burned.
Lowered the voltage to 7 volts and current limiting to 600 mA. Pushed the encoder to power up and nothing happens. Raised the power back to 12V and with one hand on the power off switch pushed the encoder. Current started climbing rapidly so power off quickly.
Tried to figure out the schematics and I get lost with all the plug numbers not being consistent between pages and some times I see multiple connector diagrams like JP101 and JP102 that seem identical as well as new to me symbols, etc. and Not really knowing how things work in the sequence I finally started this email.
Obviously something in the power up sequence has shorted, but how to trace it I'm totally at a loss.
Some help/ideas will be greatly appreciated.
Thanks!!!
73,
Cliff, AE5ZA
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Re: QMX: Kit Build complete - My observations
Good write-up, Joerg! Spot on all! I tuned in Q103/Q104 magic smoke as I was getting close to putting them in and checked with DVM for the dreaded short and found none.
Mine is finally in the box and am in ops mode now! Whole new set of things to learn. Oh, yes! You may want to review proper shut-down of PuTTY affecting the operation. There was something about CAT control if one did only disconnect from the computer or just turn the QMX off. Well, you MUST exit PuTTY properly or the radio will NOT transmit but only a few milliwatts!
--
73
Karl
KI4ZUQ
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Re: QMX successful so far - power chase
Jamie,
I would trust the scope measurements. You might try pinching the windings on L513 a little closer together to see if the power on 20/30 goes up a little bit.? Then I'd leave it alone.
Walt - KK4DF?
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Re: QMX successful so far - power chase
You won't be able to tell the difference in what you might squeeze out. I would quit before you short something out. Bruce KS4V
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-------- Original message -------- From: "James C. Hall, MD WB4YDL" <heartdoc@...> Date: 8/28/23 6:02 PM (GMT-06:00) Subject: [QRPLabs] QMX successful so far - power chase
Hello All: It appears my QMX build has gone quite well. I used a couple (actually 3) different measurements of power. I used a Elecraft DL-1 dummy load and first the diode detect method. Then I clipped to the anode side of its diode and fed that into my oscilloscope and got those readings. Realizing that the Elecraft DL is a bit different (diode at the 25 ohm end), this made the math different. Also I had to go to high impedance on the ‘scope. Anyway, power measurements are as follows: 80M - 4.20w on both methods 60M - 4.43w (diode), 4.48w (scope) 40M - 3.88w (diode), 4.07w (scope) 30M - 3.50w (diode), 3.67w (scope) 20M - 3.51w (diode), 3.80w (scope) I used a cheap Chinese QRP meter and it was 0.25 to 0.5w off everything. I used it just for a sanity check. Now, in the great watt chase, should I try to go for that extra watt, and how would I go about it ? 73, Jamie WB4YDL
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Thank you for that. I am computer caveman! I have generally a very hard time eit many of these programs and idiosyncracies of Microsoft Windows. Some hwve gone to later versions of WSJT-X and fldigi, both of which I am somewhat familiar and successful. To try those first seems prudent for now. I may try yours later.
73
Karl
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Re: QMX working FB then shorted out. Ideas?
Most likely culprits are going to be the BS170's, and possibly
IC503, from other reports.
Paul -- AI7JR
On 8/28/23 15:32, Cliff wrote:
toggle quoted message
Show quoted text
Well, guys, I'm up a creek it seems here. I'm an old guy, raised on Tubes, and don't really understand Mosfets and the schematics for the QMX are hard for me to follow.
Some suggestions to trace the issue here would be much appreciated.
I built this QMX about 3 1/2 months ago. It's been working FB with firmware 006 ever since. This morning I was using it and transmitted accidentally with no antenna attached. It's happened before with no consequences, but this time something shorted out big time. The power supply went into current limiting at 1 amp with the voltage dropped to 6 volts. Powered off with a BIG SIGH!
Opened it up and just a little smell of hot electronics, but not the usual burnt smell. Inspecting all the boards and nothing obviously burned.
Lowered the voltage to 7 volts and current limiting to 600 mA. Pushed the encoder to power up and nothing happens. Raised the power back to 12V and with one hand on the power off switch pushed the encoder. Current started climbing rapidly so power off quickly.
Tried to figure out the schematics and I get lost with all the plug numbers not being consistent between pages and some times I see multiple connector diagrams like JP101 and JP102 that seem identical as well as new to me symbols, etc. and Not really knowing how things work in the sequence I finally started this email.
Obviously something in the power up sequence has shorted, but how to trace it I'm totally at a loss.
Some help/ideas will be greatly appreciated.
Thanks!!!
73,
Cliff, AE5ZA
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QMX successful so far - power chase
Hello All:
It appears my QMX build has gone quite well. I used a couple (actually 3) different measurements of power. I used a Elecraft DL-1 dummy load and first the diode detect method. Then I clipped to the anode side of its diode and fed that into my oscilloscope and got those readings. Realizing that the Elecraft DL is a bit different (diode at the 25 ohm end), this made the math different. Also I had to go to high impedance on the ‘scope.
Anyway, power measurements are as follows:
80M - 4.20w on both methods
60M - 4.43w (diode), 4.48w (scope)
40M - 3.88w (diode), 4.07w (scope)
30M - 3.50w (diode), 3.67w (scope)
20M - 3.51w (diode), 3.80w (scope)
I used a cheap Chinese QRP meter and it was 0.25 to 0.5w off everything. I used it just for a sanity check.
Now, in the great watt chase, should I try to go for that extra watt, and how would I go about it ?
73, Jamie
WB4YDL
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Re: VFO signal generator frequency limits
Richard
The display will read out the frequency well beyond the limits of the chip to produce a signal at that reading. I checked mine and at about 100 MHz and the voltage of the signal starts to go down. At about 200 MHz it is very weak and somewhere above that no signal. I would say from those rudimentary facts the VFO is practical to use from about 3MHz to about 100MHz with out additional circuitry to boost the signal. Most of us are interested in the HF spectrum anyway and if you were interested in VHF or UHF frequencies there are other methods to get to those bands.
Bill N7EU
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QMX working FB then shorted out. Ideas?
Well, guys, I'm up a creek it seems here. I'm an old guy, raised on Tubes, and don't really understand Mosfets and the schematics for the QMX are hard for me to follow.
Some suggestions to trace the issue here would be much appreciated.
I built this QMX about 3 1/2 months ago. It's been working FB with firmware 006 ever since. This morning I was using it and transmitted accidentally with no antenna attached. It's happened before with no consequences, but this time something shorted out big time. The power supply went into current limiting at 1 amp with the voltage dropped to 6 volts. Powered off with a BIG SIGH!
Opened it up and just a little smell of hot electronics, but not the usual burnt smell. Inspecting all the boards and nothing obviously burned.
Lowered the voltage to 7 volts and current limiting to 600 mA. Pushed the encoder to power up and nothing happens. Raised the power back to 12V and with one hand on the power off switch pushed the encoder. Current started climbing rapidly so power off quickly.
Tried to figure out the schematics and I get lost with all the plug numbers not being consistent between pages and some times I see multiple connector diagrams like JP101 and JP102 that seem identical as well as new to me symbols, etc. and Not really knowing how things work in the sequence I finally started this email.
Obviously something in the power up sequence has shorted, but how to trace it I'm totally at a loss.
Some help/ideas will be greatly appreciated.
Thanks!!!
73,
Cliff, AE5ZA
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I am using omnirig instead of hamlib.?
Though I didn’t try it with qmx yet.?
73
Barb WB2CBA
?
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Chris, What does this mean?
And copying libhamlib-4.dll from the 2.6.1 install to the new version makes it work with the new versions.
Chris
I had some success today on both fldigi and WSJT-X with Kenwood TS-440S, COM6 and even QMX came up on the sound devices! But there is some kind of mutual interference on the Win 10 laptop when switching between programs. On WS the rig would go to freq and decode but would crap out* when transmit was enabled and its turn came up. Neither program would show on a power meter when "tune" was selected.
*means rig control/error box would pop up
Any suggestions? Was getting ready to load new versions on WS and fldigi....
73
Karl
KI4ZUQ
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Karl
KK4ITX John
Bruce KS4V
Paul - AI7JR
Barb WB2CBA