On Tue, Feb 13, 2024 at 09:05 PM, EA3IKB wrote:
Hi Adrian,
thanks for your suggestion. Actually when I came back from work I tried the key on Practice mode and there was some malfunctioning. So I cleaned the contacts with sandpaper and immediately the malfunctioning went away. Whether this was the entire culprit of the problem I had on the air, I will check next weekend on a new activation (I do not have an antenna at my QTH, sadly...) but it looks promising that the problem will be fixed already!!
I am new in CW and I was too shy when cleaning the contacts, I did it with a piece of paper only... I was afraid of damaging the contacts. Ok, I have learned a new thing. Thanks!
Will keep you posted.
Joan - EA3IKB
Joan, Hope you don't use regular sandpaper, you will ruin the plating from the contacts! In my previous post, I've mentioned very fine grained (800 grit) sandpaper used for shining guitar frets, that's the one you should use. Regards, YO3GFH op. Adrian
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QDX-M, 10m Band, T1 Core Material. Power Output
I am testing a QDX-M for the 10m Band. I would like to find out if there is any difference in power output at this frequency using the supplied BN43-202 core for the T1 transformer by comparing it with the BN61-202 core. ?I have fitted header sockets for the T1 transformer to save re-soldering the board. The transformer leads make good connection with the PCB. T1 is wound the same for 9 volts for both cores. I measured the primary inductance of the 43 core (23.5 uH) with the secondary open circuit and found 0.08 uH with the secondary short-circuited. The secondary circuit measured the same. The primary and secondary inductance of the 61 core was lower as expected: 4.3 uH (opposite winding shorted: 0.08 uH). These measurements were not done at signal frequency. ?
?
The power output (43 core) was measured as about 3.9 W (repeated); the power input was 9.0 volts x (0.85A-0.15A) = 6.3 W (The RX = 0.15A), ? ? ? ? ? ? ?Efficiency about 62%
The power output (61 core) was measured as about 3.8 W (repeated); but the power input was lower: 9.0 volts x (0.77A-0.15A) = 5.6 W ? ? ? ? ? ? ? ? ? ? ? ? ?Efficiency about 68% ?
My SWR/Power meter is an old Daiwa CN 620B and using the 20W fsd range. I have once calibrated it with a 50 ohm load and using an oscilloscope. Needs to be checked again with a better oscilloscope. ? ?
The power outputs are very close but the power input difference is about 0.7 W?
Typical output on 10m is quoted as 3 - 4 W. My outputs seem OK, but I cannot explain the power input difference. ?The T1 impedances for 43 and 61 cores are quite different. I'm no expert but I have read that the transformer has to be matched with the combined output impedances of the BS170s and the input impedance of the LP Filter? Their impedance difference does not seem to bother the BS170s??
Perhaps more data is needed for a conclusion.
Comments?
73, Robin?
?
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Since the upgrade to firmware 16, I can no longer tune lower than 20 meters to listen, QMX reverts to 14.074 regardless if CAT control or stand alone.
I was using HDSDR to listen to other 30 and 40 meters ham bands and can no longer do this.
I don't think QMX is capable of doing this by itself, not as far as I know. The firmware upgrade would have done a configuration reset implicitly. Are you sure you hadn't made some edits in the band configuration menu which you've long forgotten? I'm assuming yours is a high-band QMX. So maybe it's as simple as reducing the lower frequency limit of the 20m band column in the band configuration screen?
73 Hans G0UPL
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Hello,
Since the upgrade to firmware 16, I can no longer tune lower than 20 meters to listen, QMX reverts to 14.074 regardless if CAT control or stand alone.
I was using HDSDR to listen to other 30 and 40 meters ham bands and can no longer do this.
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Hi Yannig,
the cleaning of the contacts as suggested by Adrian seems to have kind solved the problem on practice mode. I will add a counterpoise in my next activation and see how it behaves. Probably even not entirely necessary, the addition of a counterpoise will make the antenna more efficient. Will let you know.
Thanks for stepping in!
Joan - EA3IKB
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Hi Adrian,
thanks for your suggestion. Actually when I came back from work I tried the key on Practice mode and there was some malfunctioning. So I cleaned the contacts with sandpaper and immediately the malfunctioning went away. Whether this was the entire culprit of the problem I had on the air, I will check next weekend on a new activation (I do not have an antenna at my QTH, sadly...) but it looks promising that the problem will be fixed already!!
I am new in CW and I was too shy when cleaning the contacts, I did it with a piece of paper only... I was afraid of damaging the contacts. Ok, I have learned a new thing. Thanks!
Will keep you posted.
Joan - EA3IKB
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Re: QMX V3? What does V3 bring?
Hello Colin
The BPF is a series resonant LC circuit, and a 1:4 multiplexer selects one coil tap of the inductor, and one capacitor. There are a lot of parasitic elements present in the circuit, including PCB trace inductances and capacitances, and the capacitance of the MUX chip input pins, self capacitance of inductor windings, and probably more.?
I expected QMX and QDX would be the same on this area. Nobody more surprised than me. But somehow the interaction of the parasitic elements managed to change everything.
Exactly how: still a mystery!
73 Hans G0UPL
Hans, I love reading your updates and circuit theory. I was wondering if you had an update to the cause of the V1 receiver change? I still find it amazing that the QDX and the QMX V1 receiver filters do not?function not the same. Colin - K6JTH
Hello Dave
Sorry for the lack of clarity. There are 1,000 PCBs arriving here in 2-3 days which cleared customs today. They are all Rev 3. So all pending kit orders will be shipped Rev 3 boards.?
73 Hans G0UPL
On Tue, Feb 13, 2024, 8:09?PM Dave Schmidt < dgschmidt@...> wrote: Thanks for the info Hans!
So is the shipment of V2 boards you are waiting for going to ship as V3?? Or is V3 still in fab?
Dave
--
Colin - K6JTH?
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Re: Removing SOIC Chips (QMX IC402)
I was in your shoes a few weeks ago. I've never done hot air work before so ordered a Yihua rework station and a few IC402 replacements as well and went to town. I started on a pretty low heat setting (500F I think) and held it on the chip for maybe 10 seconds. The whole board and all its components heat up quite a bit in the process, so I was very conservative with the heat application to try and prevent frying anything else on the board. That didn't work so I let the board cool off and then upped the heat. I repeated this process probably 10 times before I was getting to a pretty high heat setting (maybe around 900F) and then was really scared I was going to overheat other components, but the solder still wouldn't melt. Eventually I just went yolo on it with a high heat setting and held it there for longer than I was comfortable with and got the chip to melt off. I think the dual ground planes really pull the heat away from the component. Definitely wait until it's floating on the melted solder to pull it off and don't try to pry it at all or you'll pull the traces off the board and then you have a whole other set of problems.
I just used a soldering iron and the residual solder on the pads to reattach the new chip, adding a tiny bit of new solder where it seemed necessary. Apparently I didn't fry anything cause it's been working fine ever since. Was still pretty nerve-wracking though.
And for the diode I just used the soldering iron. Blasting that area with the hot air gun seemed like a bad idea.
Best of luck!
Brad
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Re: QMX V3? What does V3 bring?
Hans, I love reading your updates and circuit theory. I was wondering if you had an update to the cause of the V1 receiver change? I still find it amazing that the QDX and the QMX V1 receiver filters do not?function not the same. Colin - K6JTH
Hello Dave
Sorry for the lack of clarity. There are 1,000 PCBs arriving here in 2-3 days which cleared customs today. They are all Rev 3. So all pending kit orders will be shipped Rev 3 boards.?
73 Hans G0UPL
On Tue, Feb 13, 2024, 8:09?PM Dave Schmidt < dgschmidt@...> wrote: Thanks for the info Hans!
So is the shipment of V2 boards you are waiting for going to ship as V3?? Or is V3 still in fab?
Dave
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Colin - K6JTH?
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Re: QMX V3? What does V3 bring?
Hello Dave
Sorry for the lack of clarity. There are 1,000 PCBs arriving here in 2-3 days which cleared customs today. They are all Rev 3. So all pending kit orders will be shipped Rev 3 boards.?
73 Hans G0UPL
On Tue, Feb 13, 2024, 8:09?PM Dave Schmidt < dgschmidt@...> wrote: Thanks for the info Hans!
So is the shipment of V2 boards you are waiting for going to ship as V3?? Or is V3 still in fab?
Dave
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Re: QMX V3? What does V3 bring?
Thanks for the info Hans!
So is the shipment of V2 boards you are waiting for going to ship as V3?? Or is V3 still in fab?
Dave
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Re: Removing SOIC Chips (QMX IC402)
I have removed a few IC402's just hot air and tweezers.? I do use some aluminum flashing to screen off local components from the hot air.
When replacing, I think it was Hans, recommended using Blue Tac to keep the SMD's in place while soldering.?
I find that sometimes a pin is not properly soldered although looks good under the microscope.? I recommend checking continuity between the pad and pin.??
Note the replaced soldering will look uglier than the original. If you look at the PPT needed mod you will see even the QRP-labs change IC402 looks fairly ugly:
https://www.qrp-labs.com/qmx/qmxpttmod.html#galleryd20f63044e-3
I hope this helps, good luck
Chris
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Removing SOIC Chips (QMX IC402)
So I have a replacement on the way (several, actually, just in case), along with some diodes for the Q508 related fix for the QMX.
I have a hot-air rework tool, and have some finer tips on order for it, but was wondering if that is the best bet for removing IC402.
I have also seen suggestions on the group for using a small sharp blade ("carpet cutter") to cut the pins, lift off the carcass of IC402 and then desolder the pins. I have also seen a reference to using a dental tool during the process.
Given that I have a hot-air tool (Yihua), would it make the most sense and just do the obvious and use that to heat up the pins to remove it? Are there other suggestions?
72 JRJ W9IYN
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Re: QMX no / very low receive audio in WSJT-X
I have confirmed that my issue is indeed IC402. I applied the diagnostic fix that was posted by Chris
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Re: QMX V3? What does V3 bring?
And P.S. There is NO reason to try to change to a Rev 3 board... no change in functionality!
Hello Dave
Rev 3 is not here yet. The cargo cleared customs today in Izmir so I expect the last 250km by road to take 2-3 days. The changes from Rev 2 -> Rev 3 are minor, as follows:
1. Moved L402 a little away from C437
This was just because there was a very occasional tendency for a solder bridge to occur here.?
2. Q202 source changed +12V to +5V
After this change, the?microcontroller GPIO port PB4 (pin 90) never sees more than?+5V. Previously it saw the full supply voltage e.g. +12V via 100K resistor R209. Technically this probably exceeds the GPIO pin specification, arguably, depending on how you interpret the datasheet. There is no reported instance of any damage or failure which could be causally linked to this. However, just for the sake of good practice, I made the change to connect the Q202? source to?+5V instead of?+12V. Circuit?operation is unaltered by this but it avoids the potential specification breach.?
3. Added R115 100K LIN_REG_EN to Gnd
This is similar to point 2, above. Now on GPIO port pin PD7 (pin 88) which could also see the full?+12V supply?via a 100K resistor. Again no known instance of any failures can be causally linked to this potential breach but for good practice, it is prudent to avoid it. So I added a new 100K resistor R115 from LIN_REG_EN to Gnd. That ensures that the voltage at this GPIO pin is halved, so it doesn't exceed 6V. Yet it does not affect the functionality of the supply switchover circuit from linear to SMPS buck converters.?
4. Changed D108 to 5.6V, 5W zener diode.?
This can potentially provide a greater degree of protection against voltage spikes in the millisecond interval that it takes the SMPS buck converter control loop to counter any increases in supply voltage. Note that this has already effectively been 5W for several hundred kits already?because the SMPS boards were also manufactured and sold separately.?
It's also a very long story - that did cause several weeks of pain here - the 3.6V zener in the 3.3V supply was also changed to a 5W type. But who knew, you just can't do that. Briefly: zener diodes below 5V have a very very shallow action. There are two mechanisms, the zener break-down and avalanche breakdown. Below 5V or so, the zener break-down is dominant and it is very gradual indeed. A diode specification includes the current at which the voltage measurement is made. If you intend to operate at any other current, you better beware, the voltage will be totally different! This was all new to me and I had to do a great deal of experimentation to unravel it, then we obtained 500 3.6V 500mW diodes again and had to swap out all the 5W diodes on the separately made SMPS boards. That's why you see a red glass diode on some boards.?
5. Enlarge USB-C pads
Just an attempt to get better soldering of the USB-C connector.?
6. Change C509 from 100nF to 1nF
7. Change R510 from 10K to 470K
This modification was already made, by us, to all Rev 2 boards shipped as kits and assembled radios.?
8. Add D516 1N4148 to TxRx switch
The modification required to Rev 2 boards, described here:?
Which has already been made, by us, to all Rev 2 boards shipped as kit or assembled radio, from the start of 2024.?
9. Change Qnn names to Q5mm on page 5
Just to tidy up and make the component naming consistent!
On Tue, Feb 13, 2024 at 6:26?PM Dave Schmidt < dgschmidt@...> wrote: I ordered a QMX V2 kit in late January knowing it was delayed until early Feb, but when I was on the website checking my order, I see there is now a V3 of the QMX.
Anyone know what the V3 changes are?
Dave
AI6VX
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Re: QMX V3? What does V3 bring?
Hello Dave
Rev 3 is not here yet. The cargo cleared customs today in Izmir so I expect the last 250km by road to take 2-3 days. The changes from Rev 2 -> Rev 3 are minor, as follows:
1. Moved L402 a little away from C437
This was just because there was a very occasional tendency for a solder bridge to occur here.?
2. Q202 source changed +12V to +5V
After this change, the?microcontroller GPIO port PB4 (pin 90) never sees more than?+5V. Previously it saw the full supply voltage e.g. +12V via 100K resistor R209. Technically this probably exceeds the GPIO pin specification, arguably, depending on how you interpret the datasheet. There is no reported instance of any damage or failure which could be causally linked to this. However, just for the sake of good practice, I made the change to connect the Q202? source to?+5V instead of?+12V. Circuit?operation is unaltered by this but it avoids the potential specification breach.?
3. Added R115 100K LIN_REG_EN to Gnd
This is similar to point 2, above. Now on GPIO port pin PD7 (pin 88) which could also see the full?+12V supply?via a 100K resistor. Again no known instance of any failures can be causally linked to this potential breach but for good practice, it is prudent to avoid it. So I added a new 100K resistor R115 from LIN_REG_EN to Gnd. That ensures that the voltage at this GPIO pin is halved, so it doesn't exceed 6V. Yet it does not affect the functionality of the supply switchover circuit from linear to SMPS buck converters.?
4. Changed D108 to 5.6V, 5W zener diode.?
This can potentially provide a greater degree of protection against voltage spikes in the millisecond interval that it takes the SMPS buck converter control loop to counter any increases in supply voltage. Note that this has already effectively been 5W for several hundred kits already?because the SMPS boards were also manufactured and sold separately.?
It's also a very long story - that did cause several weeks of pain here - the 3.6V zener in the 3.3V supply was also changed to a 5W type. But who knew, you just can't do that. Briefly: zener diodes below 5V have a very very shallow action. There are two mechanisms, the zener break-down and avalanche breakdown. Below 5V or so, the zener break-down is dominant and it is very gradual indeed. A diode specification includes the current at which the voltage measurement is made. If you intend to operate at any other current, you better beware, the voltage will be totally different! This was all new to me and I had to do a great deal of experimentation to unravel it, then we obtained 500 3.6V 500mW diodes again and had to swap out all the 5W diodes on the separately made SMPS boards. That's why you see a red glass diode on some boards.?
5. Enlarge USB-C pads
Just an attempt to get better soldering of the USB-C connector.?
6. Change C509 from 100nF to 1nF
7. Change R510 from 10K to 470K
This modification was already made, by us, to all Rev 2 boards shipped as kits and assembled radios.?
8. Add D516 1N4148 to TxRx switch
The modification required to Rev 2 boards, described here:?
Which has already been made, by us, to all Rev 2 boards shipped as kit or assembled radio, from the start of 2024.?
9. Change Qnn names to Q5mm on page 5
Just to tidy up and make the component naming consistent!
On Tue, Feb 13, 2024 at 6:26?PM Dave Schmidt < dgschmidt@...> wrote: I ordered a QMX V2 kit in late January knowing it was delayed until early Feb, but when I was on the website checking my order, I see there is now a V3 of the QMX.
Anyone know what the V3 changes are?
Dave
AI6VX
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Re: QDX only powering up when USB is connected
Okay, fair enough, I don’t have a QDX or the amp.
There must be a difference with them in the position of the power socket relative to the panel and then the panel hole size matters.
73, Rowan.
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Re: #qcxmini Can't adjust I-Q Balance, Phase Lo or Phase Hi
#qcxmini
Yes. A piece of the toroid magnet wire with enamel removed from both ends is what I meant. Should work fine.?
Good luck…Ron
On Mon, Feb 12, 2024 at 19:58 Pat K7GUD < pxforti@...> wrote: Thanks Ron. I'll give it a try. Can I use the magnetic toroid wire and just clean the ends? Or do I need coated wire?
If that doesn't work, I'll send it to an expert/you ;)
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Alan Wolke has a number of excellent videos on scope basics:?
I don't see a playlist just for scope basics, but the video titles are useful and informative.
On Tue, Feb 13, 2024, 06:55 Bryan Curl < bc3910@...> wrote: I finally replaced my oscope which I foolishly sold years ago. but struggle to remember how to use it.
does anyone know agood online resource to study up on using one?? im not taking about how to use the buttons and features but rather it's practical common uses.? like when to user the 1x,10x, twin lead probes, tracing circuits, do's and don'ts,? e.t.c.?
--
regards,
Bryan, N0LUF
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QMX V3? What does V3 bring?
I ordered a QMX V2 kit in late January knowing it was delayed until early Feb, but when I was on the website checking my order, I see there is now a V3 of the QMX.
Anyone know what the V3 changes are?
Dave
AI6VX
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Colin Kaminski
cube1us
Ronald Taylor