Hi folks?
See attached... Just me and the sleeping Lab Tech-mini, a glass of fresh pomegranate juice by the river. WX 23C sunshine... And remoting from my mobile phone into QRP Labs Towers for a bit of QDX fun on 20m FT8...?
73 Hans G0UPL http://qrp-labs.com
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Re: QCX 50W Amp - Low RF Output
#20m
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Werner,?
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the situation you describe - low power , a bout half expected output? seems to arise , historically where people have one side of the class C pair??working but for component failure reason or bad soldering reason the other side of the push push circuit is?not working.? NB your supply would need to be good for around sixty W if you want this unit to supply 25 W out? - read on
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1. CHeck that you do have the bias voltage available when the PTT is triggered. By which a Mean a full five?
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volts out off the regulator.? Perhaps the regulator has failed or is at some lower voltage.? Generally if you?
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put in a five volt regulator 78LM type backwards it simply does not function.??
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2? Trace that voltage across to the? R5 potentiometer.? Check that this is really a five K unit. If it is 10K?
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or something like that then the return signal in the? gate path is throttled.? ?check it is physically?
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assembled correctly and the slider is bearing well.
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3.? check that the bias (once the PTT is asserted) is getting all the way to the respective MOSFET gates.? Bad?
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stripping of the? wire in the trifilar transformer could be the issue - it might look like a good solder joint?
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but one of the gate joints might be defective.
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4. At this point if the phasing TFR? is built and stripped correctly with the correct phasing then you have to?
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start suspecting the MOSFETs.
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5 if you put a? leaded one ohm resistor in the Drain leg of each mosfet as? a temporary connection you can see?
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they are responding properly in static mode to increases in common gate? bias. Clearly you have to measure the?
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voltage under the respective resistor to GND and watch it for both Mosfets.
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6. Did you put in the RF? OPut transformer with the three turn secondary pointing in the correct direction ?.?
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I am guessing this might be a common fault for those who do not follow directions precisely. :
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At nineteen volts supply and with 5 W RF in then you should have about 25 W out.? This is a class C device . If?
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feed it with say 2.5 W in you will get to next to nothing out, far less than a proportional calculation would??suggest.?
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TE Fidler
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Re: QDX - No RF output, Tx line stays low
Hi Hans,
The issues that I am seeing are on the first connection.? It seems that once I get it connected successfully it can run in receive mode for hours without any issues.? I had only one instance where the sound interface failed after a few minutes of running.? Since that one time, I have not had another failure after the first successful decode on FT8.? I have not tried many transmissions, maybe 6 to 7 attempts and 4 QSOs on FT8.? There were no dropouts on transmission.?
I also had a friend come over to look into his QDX low power output.? His laptop is running Windows 10, and we had issues getting it to connect.? Once we did get it connected there were no issues.? It was the startup sequence that seems to impact the connection quality.
It should be noted that I have only used FT8 so far.? I do not have the JS8Call program loaded on any of my computers nor have I tried the WSPR mode of WSJT-X that I do have on most of my PCs and the Raspberry Pi.
I went through the Windows System Events but could not find any errors that might help explain the USB drops.
73
Evan
AC9TU
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Re: QDX - No RF output, Tx line stays low
Hi Alan
I thought that in your earlier email, you were referring to Windows sound devices. Not CAT.?
CAT drop outs are likely a different thing. We need to get to the bottom of whether there are OS USB sleep issues, or QDX firmware issues, or differences in application software, or common mode feedline RF issues.?
In my own case here (Linux XUbuntu 18.04, QDX Rev 1 PCB, 12V built, Firmware 1.01c but same on all)... I have seen occasional drop-out of CAT only, and only on JS8Call, and only when actually transmitting.?
I have not seen it while JS8Call is only monitoring. Nor have I seen it on WSJT-X. I do have a known common mode feedline current problem that I tackle via 10 turns coax on FT240-43 ferrite toroid. And I have a ferrite clip-on on the USB cable.?
The fact it happens only on JS8Call during transmit seems to indicate RF interference.?
On the other hand why does it not happen on WSJT-X when I'm operating FT8...?
Anyway I think we are all collecting evidence and we'll get to the bottom of these issues between us.?
I did have a nice QDX 40m JS8Call QSO last night with Steve CT7ANL 3,300km West of me. See attached. I was particulalry proud when he said that my Ultimate 3S was what had got him interested in data modes.?
73 Hans G0UPL http://qrp-labs.com
-------- Original message -------- From: Alan G4ZFQ <alan4alan@...> Date: Sun, Nov 14, 2021, 11:37 AM To: [email protected]Subject: Re: [QRPLabs] QDX - No RF output, Tx line stays low On 14/11/2021 08:27, Hans Summers wrote:
>The question is: what
> is different in Windows cases like yours, where it isn't working?
Hans,
That's what I'm wondering after attempts on a W7 netbook, W7 laptop, W10
PC. All into a dummy load and CAT drops out after a few hours maximum
WSPR, still testing.
73 Alan G4ZFQ
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Re: QDX - No RF output, Tx line stays low
Hi Hans,
I went back and was able to cause the USB sound issue.? It happens if you power up the QDX THEN connect the USB cable.? This time when I did the 3 power cycles it did not connect.? I had to reboot the PC, connect all the cables, power on the QDX,? Power down the QDX, and then apply power once more.? This was after I had used the QDX with the Windows PC most of the day.? It is the USB audio card link that is failing to start correctly.
I am open to suggestions on how to proceed.? I have a way to get it to work, so I can use it.? I would like to help find out what is happening.
73
Evan
AC9TU?
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Re: QDX - No RF output, Tx line stays low
On 14/11/2021 08:27, Hans Summers wrote: The question is: what is different in Windows cases like yours, where it isn't working? Hans, That's what I'm wondering after attempts on a W7 netbook, W7 laptop, W10 PC. All into a dummy load and CAT drops out after a few hours maximum WSPR, still testing. 73 Alan G4ZFQ
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Re: QDX - No RF output, Tx line stays low
Hi Alan
QDX *is* supposed to be like that and for many people, that's exactly how it is working. I plug in QDX and it "just works"... OK I'm on Linux but many Windows ops have reported success too... The question is: what is different in Windows cases like yours, where it isn't working??
73 Hans G0UPL http://qrp-labs.com
-------- Original message -------- From: Alan G4ZFQ <alan4alan@...> Date: Sun, Nov 14, 2021, 11:10 AM To: [email protected]Subject: Re: [QRPLabs] QDX - No RF output, Tx line stays low On 14/11/2021 07:07, Evan Hand wrote:
> I either get operation as
> normal or the input bar is either high or low red meaning no audio or
> too much audio.? Two more power cycles and it is back to mid-level
> green.?
I have much the same experience.
CAT is lost. Sometimes around 3 startup attempts before it works again
for a while.
Several times on startup or during an attempt to recover from lost CAT I
have seen a giant signal sent to WSJT-X. It is white noise at a very
high level.
I was hoping the QDX would be like a USB sound device and initialise and
startup? when booting Windows but no way.
73 Alan G4ZFQ
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Re: QDX - No RF output, Tx line stays low
On 14/11/2021 07:07, Evan Hand wrote: I either get operation as normal or the input bar is either high or low red meaning no audio or too much audio.? Two more power cycles and it is back to mid-level green. I have much the same experience. CAT is lost. Sometimes around 3 startup attempts before it works again for a while. Several times on startup or during an attempt to recover from lost CAT I have seen a giant signal sent to WSJT-X. It is white noise at a very high level. I was hoping the QDX would be like a USB sound device and initialise and startup when booting Windows but no way. 73 Alan G4ZFQ
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Re: BNC connector position on the QCX mini
Thanks guys!
I will try to make sure it¡¯s parallel to the PCB. And maybe use an enclosure to check if it fits nicely.
73, Victor PA8MM?
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Re: QDX - No RF output, Tx line stays low
Hi Hans,
When it does happen, the LED is on solid, with no flashing.? I wait until it is solid before opening WSJT-X.? Then I either get operation as normal or the input bar is either high or low red meaning no audio or too much audio.? Two more power cycles and it is back to mid-level green.? Since following my startup-sequence I have not seen it again.? I will see if I can replicate what causes the problem and post back to you if I do.
73
Evan
AC9TU
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Re: QDX - No RF output, Tx line stays low
Hi Evan
To know where QDX is in firmware update mode or not, you only need to look at the status LED. A slow continuous flash means firmware update mode.?
In power up in normal operating mode the status LED flickers quickly for 5 seconds. During this time if you disconnect power and reconnect, it will enter firmware update mode.?
There are a lot of posts and I can't refer to it precisely but I seem to remember someone posting their sequence of operations, their recipe for success... That included waiting for the status light flickering to stop and become steady. In fact this is not necessary. QDX operates in those first 5 seconds, there is no need to wait for connecting PC etc. You don't need to wait for the steady LED.?
73 Hans G0UPL http://qrp-labs.com
-------- Original message -------- From: Evan Hand <elhandjr@...> Date: Sun, Nov 14, 2021, 9:36 AM To: [email protected]Subject: Re: [QRPLabs] QDX - No RF output, Tx line stays low Hi Hans,
I still do not know what the underlying issue is with the two Windows 10 systems that I have tried so far.? I can say that I can now reliably connect and use the QDX on one of them, it may just take 3 restarts to get it to work.? I do not have that issue with the Raspberry Pi system unless I first have the issue with one of the Windows systems.? So it seems to be a state issue in the QDX that can take 3 power cycles to resolve.? Once resolved it does work well on both systems.? Maybe it has something to do with the upgrade system in the QDX.? Not sure that I have the tools to work this one out.
As long as I know about the 3 power cycle fix, I see it only as a nuisance.? If you are careful on the first startup after a power down it does not happen.? The sequence seems to be the thing:
1 Connect the antenna and USB cable
2 Be sure the PC is on and ready to go
3 Connect the QDX power
4 Then start whatever program you want to connect to.
If the program will not work, then power off the QDX, reapply power, and try again.? You may have to repeat this a second time to get it to work.? If I do need to start again, I always start with the terminal connection to ensure it is not in update mode.? I also ensure that I always exit out of terminal mode before closing the PuTTY program.? A power switch on the QDX would have made this easier.? I am looking into modifying the case and board to see if I can squeeze one in.? I have two extra to experiment with as two of our builders opted not to build the kit.
73
Evan
AC9TU
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Re: QDX - No RF output, Tx line stays low
Hi Hans,
I still do not know what the underlying issue is with the two Windows 10 systems that I have tried so far.? I can say that I can now reliably connect and use the QDX on one of them, it may just take 3 restarts to get it to work.? I do not have that issue with the Raspberry Pi system unless I first have the issue with one of the Windows systems.? So it seems to be a state issue in the QDX that can take 3 power cycles to resolve.? Once resolved it does work well on both systems.? Maybe it has something to do with the upgrade system in the QDX.? Not sure that I have the tools to work this one out.
As long as I know about the 3 power cycle fix, I see it only as a nuisance.? If you are careful on the first startup after a power down it does not happen.? The sequence seems to be the thing:
1 Connect the antenna and USB cable
2 Be sure the PC is on and ready to go
3 Connect the QDX power
4 Then start whatever program you want to connect to.
If the program will not work, then power off the QDX, reapply power, and try again.? You may have to repeat this a second time to get it to work.? If I do need to start again, I always start with the terminal connection to ensure it is not in update mode.? I also ensure that I always exit out of terminal mode before closing the PuTTY program.? A power switch on the QDX would have made this easier.? I am looking into modifying the case and board to see if I can squeeze one in.? I have two extra to experiment with as two of our builders opted not to build the kit.
73
Evan
AC9TU
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I didn't know gas tube lightning protectors before reading here. Does the ground connection need to have a dedicated grounding (hard to achieve from my flat on the second floor of a bulding...) or can it be connected to the ground pin of any AC outlet in the house?
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Re: QDX - No RF output, Tx line stays low
Hi Evan?
I did test on Windows. It takes a while to boot up but if you're patient Win10 does work OK. I find it frustrating but it works.?
I didn't have any problems connecting or operating QDX from Windows. Quite a few reports from other users here also confirm the same. So Windows works... But then again other people are having problems with it. So it seems not all Windows systems are equal.?
73 Hans G0UPL http://qrp-labs.com
-------- Original message -------- From: Evan Hand <elhandjr@...> Date: Sun, Nov 14, 2021, 7:21 AM To: [email protected]Subject: Re: [QRPLabs] QDX - No RF output, Tx line stays low Hi Ben,
Congratulations on finding the problems and the QSO.
FYI, I too have the issue of needing to power cycle the QDX a number of times to get a connection.? I have the issue on more than one Windows PC, so it is a compatibility question with Windows.? As Hans has stated he has not done extensive testing with Windows as he has a long startup situation with his current Windows PC.? I was given a tip to disable the suspend function for the USB connections.? That may have helped in reducing the reoccurrence of the problem, but I was able to connect prior to making the change.? The tip is in this message from Gregg Myers:
/g/QRPLabs/message/74548
I have found that after I get the QDX connected it does work well.
73
Evan
AC9TU
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Re: QDX - No RF output, Tx line stays low
It may seem counterintuitive, but this tool works better if there is plenty of solder on/in/around the hole. The reason is that with more solder, there is more contact with the tip of the desoldering tool, so more heat flows all the way through the via to the other side and melts the solder on the other side too, which is critical for a good clear. You really want to have to do it only once, otherwise too much pressure and the high (420C) temperature will damage &/or lift the pad, so be brave, add enough extra solder to cover the entire flat surface of the tool tip.
This technique of adding a little extra solder is especially important if the hole you're trying to clear is on the ground plane, which will do its darnedest to pull all the heat away and prevent a successful clear.?
As with all soldering, make sue the board is properly restrained and not wobbling around, plan your angle of approach, make sure you don't touch plastic parts with the shaft of the tool, and be careful not to slip and remove surface mount parts instead.
--
Julian, N4JO.
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Re: QDX - No RF output, Tx line stays low
Jay,
I have found a tool like this to be the best:
Note: This is not the exact tool that I have, as I cannot find the link that I used a couple of years ago.
I find that positioning the hole of the tool right over the lead sticking through, putting slight pressure on the lead until I feel it give a little, then try to center and then release the bulb.? Be sure to squeeze the bulb with you thumb before you put it over the board.? I have an old box that I keep beside the work surface that I pump the bulb a couple of times to clear before going to the board to remove the part.? Again, be sure to squeeze the bulb away for anything that can be damaged, and holding the bulb squeezed, place it on the joint to be processed.
Here is the video that I used to learn how to do it:
I have not had a solder pad lift using this tool and technique.? Your mileage may vary.
73
Evan
AC9TU
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Re: QDX - No RF output, Tx line stays low
Thanks for the advice, Evan. How did you clear the solder from the BS170 holes? I tried wick and was only successful with 2 holes. I didn¡¯t want to be too aggressive as the pads were starting to lift.?
Jay
toggle quoted message
Show quoted text
On Saturday, November 13, 2021, 9:38 PM, Evan Hand <elhandjr@...> wrote: Hello Jay,
FWIW, I had to replace IC5 after determining that it was not working.? I removed the 4 BS170 MOSFET finals and then tested the output of IC5 to the gate pads.? One side had nice square wave signals, the other did not.? IC5 was bad, probably taken out when the finals became resistors and not MOSFETs anymore.
To repair IC5, I simply cut off all of the leads of IC5 with a fine diagonal cutter right next to the IC.? Clip parallel to the chip side to reduce any strain on the pad.? ?I then cleaned off the left behind leads with my iron and solder wick. Then installed the 74ACT08 replacement.? I verified that the drives to the gate pads were correct (On the first test I found that one of the output leads of IC5 had a cold joint) and then installed the BS170s.? I would have had issues if I had not found the joint issue with one of the pins on IC5.
You might want to replace all 4 of the BS170 MOSFETs while you are at it.? The ones that check out as OK could be weakened, and they are not that expensive.? Better to start with a fresh set of tested BS170s.
If you do decide to use Chip Quick be sure to clean off all of the solder after the removal of the IC as per the instructions.? That solder is very brittle and will cause long-term issues if not removed properly before installing the new part.
Good luck with the repair.
73
Evan
AC9TU
--
Jginaz
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Hello Mike,
As others have stated, it MAY be OK.? If it were a kit I was building I would strip the wire from the toroid, deburr the toroid, and then rewind.? If you will not be moving the QDX much, then the other fixes should be OK.? I did have the same issue with T1.? Deburring and careful inspection is required for all ferrites,?
Again, this is the way that I would do it.? Others have had success with their repairs.
73
Evan
AC9TU
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Re: Qdx smoked - USB
#qdx
I too had an issue with sharp edges on T1, even after a quick deburring.? I noted the issue and had to strip out the wire, do an aggressive deburring, and replace it with fresh wire.? Good thing I had the right size wire.
I did not see or feel burs on the toroids, just the binocular core.
I did share this with my club build group, did not post it on the Groups.io server.
73
Evan
AC9TU
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Re: QDX issues: Measuring L
I put a 100 ohm carbon resistor in series with the inductor and do a simple Smith chart centered on your target frequency. Set Marker > Smith VALUE > R+L/C. ?Put on your glasses and read the upper right corner.
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Timothy Fidler
Leonardo IW5CWC
Julian N4JO