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Re: QDX-M and 630m

 

Hello Glenn

Ros EX0AA did designs for LF for QDX-M and I need to test and document them and put them in the shop. One more thing on my long ToDo list. Along with an 8m QDX-M too. And all the bands in between.

73 Hans G0UPL


On Fri, Sep 29, 2023, 7:53 PM Glenn VE9GJ <ve9gj@...> wrote:
Has anyone built a QDX for 630m? If so would you share the toroid cores and turns that were used?

73
Glenn VE9GJ

Re: QDX-M and 630m

 

Hello Glen,
I have 3 QDX-M units running at 2200m, not what you want, but I can describe the process I used to design the toroids and turns.
Before I do that, there is an account of a SOTA activation that we did, with pics including the modified QDX-M here:


First, Ross VK1UN helped me with the design of the low pass filter. This uses the ELSIE filter design program. http://tonnesoftware.com/elsie.html
The design process was not difficult, but I first tried to use ferrite toroids as they have a higher inductance per turn than iron toroids. Unfortunately the power rating for the ferrites was much exceeded and they ran very hot. That is when Ross directed me to the iron toroids, requiring about 100 turns each!
For the other toroids and transformers? I calculated the impedance of the inductors in Hans 12m design, and then scaled this for the same impedance at 137.5 kHz. It worked for me!

Here is the list of inductors/capacitors I used.

QDX-M modifications for 2200m band, final version (2023 09 27)
LPF Filter design by Ross Ballantyne, VK1UN
?
The components listed here refer to PCB Rev 5M
(document version 1.02 published 08-Feb-2023)
?
Part Number Toroid Wire Turns Ind.uH Function
T1 FT50A-75 24 AWG 20:(10+10) ? ? ? ?1200 ? ? ? ?9V output transformer
T2 FT50A-75 28 AWG 40:40:40 ? ? ? ? ? ? ? ? 4800 Trifilar
L4 T50-2 28 AWG 98 ? ? ? ? ? ? ? ? 51.4 ? ? ? ? LPFilter
L10 T50-2 28 AWG 101 ? ? ? ? ? ? ? ? 57.9 ? ? ? ? LPFilter
L12 FT37-75 24 AWG 9 ? ? ? ? ? ? ? ? 180 ? ? ? ? ?BPFilter
L14 FT37-75 24 AWG 30 ? ? ? ? ? ? ? ? 1680 TX power choke
?
C7 22 nF Low Pass Filter
C11 2.88 nF Low Pass Filter (2.2 + 0.68)
C14 44 nF Low Pass Filter (22 + 22)
C20 22 nF Low Pass Filter
C28 6.8 nF Band Pass Filter
?
All capacitors 100 Volt COG

One last thing, you need v1_10 of the QDX software installed, earlier versions have a bug preventing transmitting on 630 and 2200m.

Good luck,
Ian
VE6IXD?
?
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

DM5KA
 

i've uploaded an image of the main cca ...?

?

?
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

 

To build on what Rich AE8AA suggests, use a buck-boost converter.? ?That allows you to set the output voltage, and as long as enough power is supplied to the input, it will maintain the voltage.? I have used this one with good results:


It also has a current limit capability, which is not easy to set or accurate under all conditions.? The voltage setting is rock solid; it is that alternate ground returns in most ham shacks that can cause erroneous current readings.? The current limit can be used when testing with ground isolation.? An example is to use an isolated battery to supply the power so that there is no alternate path back to the battery's negative terminal.

73
Evan
AC9TU
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

DM5KA
 

Hi rich,
As I already wrote, the QMX was in use every day for a good 3 weeks. I hear more than I send, maybe a 95/5 ratio.

The power supply can be trimmed. I had it permanently set to 12.6V.

The voltage of the power supply is quite clean. However, the power supply still runs via a power filter from the company "Cosel" and has a current-compensated ring core choke and a common mode choke on the DC side.
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

DM5KA
 

Just because of the "has this been checked" messages that will inevitably follow: The device was built and checked about 3 or 4 weeks ago. Since then the QMX has been running perfectly every day ;) I have no plans to repair this device... I'm done with it ^^ The purpose of the thread is only to investigate an issue that may exist in the design.
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

 

Thanks.? Your story really does help.? You suffered a fried radio, but maybe the next guy will learn from it.

The 12V limit does matter, and it's a decent guess that your radio failed from too much voltage.? You said it ran OK for a while, before the accident.? How long did you run it?? It would be helpful to know how much receiving, and how long spent transmitting, in case there's another explanation.

I looked up your power supply.? The nameplate rating says it supplies 13.8V, up to 5 amps continuous.? You'd need a way to get an accurate 12 volts -- or better yet, less -- to use that supply safely.

You might consider adding an adjustable buck converter between your power supply and the rig.? Same goes for people who run on batteries.? Then you can set your supply voltage to what you want, and see what it is before you power on the radio.
QDX-M and 630m

 

Has anyone built a QDX for 630m? If so would you share the toroid cores and turns that were used?

73
Glenn VE9GJ

Re: QMX supply voltage reporting higher than input and strange display behavior

 

Note that the duty cycles are maxed out.? This would indicate that the voltage measurements are off and the values are in error (a high value should have a low duty cycle).? It also means that the SMPSs are not working correctly.? I would look for an open or short on the SMPS connectors.? It could also be, as Ryuji suggests, that the voltage divider is off.??

Trying to test with power applied for this design can be problematic.? The protection circuits can handle only so much abuse before they, too, give up the magic smoke.? A low-voltage supply that is current limited would be a good idea.? Better is to isolate the fault without power if possible.

73
Evan
AC9TU
Re: QMX supply voltage reporting higher than input and strange display behavior

 

On Fri, Sep 29, 2023 at 09:40 AM, Rob Giuliano wrote:

Just an "educated" guess since I don't have one, but microprocessors can't measure higher voltages directly. Since you know the voltage is not that high, I suggest you look at the resistors that make up the voltage divider to the Analog to Digital converter. They are probably not in the correct order to do the ratio that the microprocessor is expecting.

If that were the case, I would expect that the same problem happens reliably every time regardless of how many power cycles.
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

 

If the drain of Q104 is shorted to its source/ground, it simply turns on the power control circuit automatically. If the drain of Q103 is shorted to its source, nothing happens unless the power is connected in reverse polarity.

In my previous post I made a typo. 150uA not 15uA on Q104. Still too tiny to burn anything.
Re: QDX Experimental PA Simulation

 

Did anyone simulate the WTST 1:1 output transformer properly and compared a case where the two drain windings shared the magnetic circuit and another case where they are wound separately? I think the latter would function better.

This 1:1 transformer is two Guanella 1:1 balun (current balun in the phase inverter configuration) sharing the magnetic circuit. While it is working, it bothers me.

One reason is sharing the magnetic circuit when the fluxes from each halves are not the same, and another reason is that one side of the push pull gets driven at a higher voltage than the other side.
Re: QDX R2 enclosures?

 

Thanks!

Bob
EDJ

On Fri, Sep 29, 2023 at 12:08?PM Hans Summers <hans.summers@...> wrote:
Hello Bob

I'm still able to supply QDX rev 2 enclosures. I still have some in stock. If you just order a normal QDX enclosure and put a note in the customer comments part of the order form that you want the QDX Rev 2 enclosure that should do it.?

73 Hans G0UPL


On Fri, Sep 29, 2023, 5:34 PM WA1EDJ <bobc784@...> wrote:
Any QCX R2 enclosures available?? ?I have a R2 that would like one.? Apparently the new enclosures are for R3 and above.
Or, would a R3 enclosure work, just have an empty hole?

TNX
Bob
WA1EDJ

Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

 

Had this unit been checked for the potential short between the drains of Q103/Q104 prior to building?

-mike/w1mt
Re: QDX R2 enclosures?

 

Hello Bob

I'm still able to supply QDX rev 2 enclosures. I still have some in stock. If you just order a normal QDX enclosure and put a note in the customer comments part of the order form that you want the QDX Rev 2 enclosure that should do it.?

73 Hans G0UPL


On Fri, Sep 29, 2023, 5:34 PM WA1EDJ <bobc784@...> wrote:
Any QCX R2 enclosures available?? ?I have a R2 that would like one.? Apparently the new enclosures are for R3 and above.
Or, would a R3 enclosure work, just have an empty hole?

TNX
Bob
WA1EDJ

Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

 

It's interesting that you had Q104 burnt. That transistor probably never see more than 15 micro amps flowing through the drain unless something else happened, but then it's also not likely that the gate of Q103 failed in short mode.
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

DM5KA
 

Hi Rich,

The power supply is an "Abrecht SW 57". The power supply was already switched on and was simultaneously supplying a 20m QCX. I then connected the QMX to the antenna (1:9 EFRW via a tuner) and the paddle. I then plugged the barrel connector into the QMX and tried to turn it on using the volume button ....... tried to turn it on once more but nothing happend. The QMX made no sound and the backlight remained dark. I noticed the smell about 5 seconds later.

I don't think this will be of much help to others as I can't see any obvious errors. What I can say for sure is that there was too much voltage on the VDD line.

best regards
Re: QMX suddently fatal holy smoke failure #magicsmoke #qmx #rip #error

 

On Fri, Sep 29, 2023 at 09:26 AM, DM5KA wrote:
>> The QMX is a total failure without any serious user errors
>> Powersupply is at 12.6V , same powersupply which supply my qcx minis..

Sorry about your radio.? I know it's a big investment in time and effort.? And while relatively inexpensive, it's not free either.

That's a lot of damage.? But maybe we can all learn something from your experience.

Can you tell us more about how you were powering your QMX?? Were you running on batteries?? Wall-wart?? Lots of those common wall-wart power supplies have inadequate voltage regulation, and they are less predictable under light loads.

If you were running on a bench power supply, how did you power up the QMX?? Some people report that switching on a bench power supply results in a large voltage spike before the voltage regulation settles down.? For those power supplies it's better to power on the supply and only then plug in the radio's power connector.

Consensus is that the 12V limit (or 9V if you built it that way) should not be exceeded, not ever.? You reported running about 5% overvoltage.? Doesn't sound like a lot, but still, beyond specs.

Please tell us more about how the smoke got out.
Re: QDX Rx but no TX spots in WSPR

 

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Grant ,?

I just looked at your Rx spots and they are very low in QRG, I think your dial setting or calibration of the QDX is out
73
Ross
EX0AA

6

On 29 Sep 2023, at 15:11, Afghan Kabulldust via groups.io <kabulldust@...> wrote:

?Grant,

Are you on Windows or Linux? Timing is often a main reason WSPR is not decoded.?
An indicator that you computer is set to the right time is the DT value in ?the 3rd column of spot decodes in WSPR. If your DT is somewhere -2 to +2 you should get your spots being decooded. As Bojan said if your Tx frequency ?is wrong (dial on WSPR 20m is 14.095600) and your Tx offset is not -100 to +100hz then your signal will be out of the WSOR window.?
73

Ross
EX0AA
6

On 29 Sep 2023, at 13:17, Roger Hill <rhill@...> wrote:

?
Or the start time is wrong .set to start on an odd minute perhaps?

Roger
8P6RX

Get
On 29 Sep 2023, at 09:16, Bojan Naglic <bojan.naglic@...> wrote:
Hi,
it seems like nothing is coming out during the TX session (ENABLE TX?) or the TX frequency is wrong.

73 Bojan S53DZ

Re: QDX Rx but no TX spots in WSPR

 

开云体育

Grant,

Are you on Windows or Linux? Timing is often a main reason WSPR is not decoded.?
An indicator that you computer is set to the right time is the DT value in ?the 3rd column of spot decodes in WSPR. If your DT is somewhere -2 to +2 you should get your spots being decooded. As Bojan said if your Tx frequency ?is wrong (dial on WSPR 20m is 14.095600) and your Tx offset is not -100 to +100hz then your signal will be out of the WSOR window.?
73

Ross
EX0AA
6

On 29 Sep 2023, at 13:17, Roger Hill <rhill@...> wrote:

?
Or the start time is wrong .set to start on an odd minute perhaps?

Roger
8P6RX

Get
On 29 Sep 2023, at 09:16, Bojan Naglic <bojan.naglic@...> wrote:
Hi,
it seems like nothing is coming out during the TX session (ENABLE TX?) or the TX frequency is wrong.

73 Bojan S53DZ

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