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Re: QMX - Looking for troubleshooting advice

 

I'm not sure if that was the case with earlier firmware but mine does have that option in QMX.
Re: QMX - Looking for troubleshooting advice

 

Thanks for all the tips. I spent a good part of the day today just inspecting my work, trying to make sure I had to cold solder joints again...I managed to get another 0.5 watts out so now it's up to 2.5 Watts. I'm truly at a loss.?
Re: QMX - Looking for troubleshooting advice

 

I found an equivalent part from a parts radio I have and dropped it in. Unfortrunately, no change.?
Re: QMX - Looking for troubleshooting advice

 

This didn't work, unfortunately. I took my 2.5 Watts down to 1.0 watt. Spreading them apart again restored the power
Re: QMX - Looking for troubleshooting advice

 

I don't see that as an option the QMX...it only has a GPS viewer option under Hardware tests.?
Re: QDX Experimental PA Simulation

 

Thanks Tony, looking forward to reading your report.

Tony
AC9QY

On Wed, Sep 27, 2023 at 1:40?PM mux_folder2001 <canthony15@...> wrote:
I have attached a PDF of some work I did over the past few days regarding core loss modeling for my QDX. The result data actually covers 80-10 meters but I was looking at my high band unit when doing the work.

Maybe the SPICE modelers among us will be able to make use of it.

Tony
AD0VC
From: [email protected] <[email protected]> on behalf of John Z <jdzbrozek@...>
Sent: Tuesday, September 26, 2023 12:27 PM
To: [email protected] <[email protected]>
Subject: Re: [QRPLabs] QDX Experimental PA Simulation
?
Hi Tony, Hans et al,

As I had posted earlier, modelling the output transformer for QDX/QMX
is tricky business!

Proper modeling of the output transformer is complicated at the
outset. There are parasitic elements, frequency dependent
permeabilities and couplings , losses, etc.

.Ross's move to a RWTST design for the 12 Volt radios further
complicates simulation. The 12V RWTST transformer is a hybrid between
a transmission line transformer and a conventional transformer, as it
has elements of both. It is neither fish nor fowl.

Then there is the issue of the? peculiar binocular transformer core.
Ross posted a model which treated the windings through each aperture
of the binocular as separate, non-coupling inductors. Yes, when wound
in a way which avoids linking the central post of the binocular, that
is what happens! It is key to the operation of the Stockton SWR bridge
incorporated in QMX.

More Controversy!

JZ












On Tue, Sep 26, 2023 at 1:52?PM Tony Scaminaci <tonyscam@...> wrote:
>
> Hi Hans,
>
> You make valid points, especially about modeling the output transformer. I’ll leave this question to JZ as he has more expertise in this particular area. I do think his model is fairly accurate though based on the spike and power output levels we measured early on. The spike level was close to what you and others measured on the bench.
>
> John initially suggested replacing L14 with a small value resistor on the order of 1-2 ohms as a way of eliminating the key-up spike. We also experimented with keeping L14 and using the bypass cap. Both of these alternatives resulted in eliminating the spike but I don’t recall what the effect was on power output. In this respect, you may be correct. These experiments were done with the BS170s and I took it one step further and tied the transformer directly to 12V which did result in a slight increase in power output. All of these experiments were run at ~28 MHz in an attempt to improve power output on 10 meters.
>
> At this point, I began searching for a better transistor with similar specs to the BS170 but with two notable improvements: lower Vgs threshold and higher Vds breakdown voltage. Microchip’s TN0110 is an excellent drop-in replacement for QDX radios. Simply flip them upside down and you’re in business. The 1V lower gate threshold is more suitable for a 5V drive level and the 100V minimum breakdown voltage is much more effective against the L14 spike voltage. As always, it’s best if the spike never exceeds 100V… this could be achieved by a slight reduction in L14’s inductance.
>
> The TN0110 is back in stock at Mouser. I encourage you to build a QDX with this device and compare it directly against a QDX using the BS170. You’ll be pleasantly surprised at the increased power output and your customers will experience a much lower failure rate of the PA. A win for everyone.?
>
> Regards,
>
> Tony
> AC9QY
>
>
> On Mon, Sep 25, 2023 at 12:25 AM Hans Summers <hans.summers@...> wrote:
>>
>> Hi Tony
>>
>> Real world testing, it is easy to see the clear decrease in power output and efficiency if you omit L14 (the 10 turn FT37-43 choke). The difference in performance is notable and significant. The fact that your simulation produces a different result indicates to me that something isn't quite right there. I suspect accurately simulating the output transformer may be critical, a simple coupled coil model may not suffice.
>>
>> The point about driver level is also quite interesting. Back when developing the original QCX I experimented with this. In my first prototype I had an entire ACT00 logic chip driving the three parallel BS170s with all four gates in parallel. Later I needed to implement other features in the transceiver and for some of those, taking some of the NAND gates for other purposes would be useful or necessary. I wanted an inverter for the TX signal and also to be able to gate both the CLK2 signal to the PA and the signal generator. The end result was that I only had a single gate left, to drive all three BS170 in parallel. I found that a little alarming, because there are three BS170s in parallel in QCX and they are Class E, and fast clean switching is very important. So of course then I had to decide whether to add another ACT00 chip or perhaps add something some place else to free up gates again. To make that decision I made detailed power and efficiency measurements for 1, 2, 4 gate cases. I also tried one gate per BS170 gate (3 gates used). I found that there was an increase in power output and efficiency when going from 1 gate driver to 2. But it was quite a slight small improvement. There wasn't any significant improvement in going from 2 to 4. Driving the gates one by one (one gate per BS170 separately) actually made things slightly worse; for whatever reason, paralleled gates seem to work better. Accordingly with these observations in hand, I felt happy sticking with the single gate drive for QCX. Then when it came to QDX where:
>>
>> 1. There are 2 gates per driver not one;
>> 2. There are 2 parallel transistors not 3;
>> 3. It isn't Class E so it's a little less critical;
>> I felt entirely comfortable with 2 gates driving 2 parallel BS170s on each side.
>>
>> So I haven't tried doubling up a piggy back ACT08 but it would be an interesting experiment for someone; personally it would surprise me if doubling up made a significant or even noticeable improvement.
>>
>> 73 Hans G0UPL
>>
>>
>
>





Re: QDX Experimental PA Simulation

 

开云体育

I have attached a PDF of some work I did over the past few days regarding core loss modeling for my QDX. The result data actually covers 80-10 meters but I was looking at my high band unit when doing the work.

Maybe the SPICE modelers among us will be able to make use of it.

Tony
AD0VC

From: [email protected] <[email protected]> on behalf of John Z <jdzbrozek@...>
Sent: Tuesday, September 26, 2023 12:27 PM
To: [email protected] <[email protected]>
Subject: Re: [QRPLabs] QDX Experimental PA Simulation
?
Hi Tony, Hans et al,

As I had posted earlier, modelling the output transformer for QDX/QMX
is tricky business!

Proper modeling of the output transformer is complicated at the
outset. There are parasitic elements, frequency dependent
permeabilities and couplings , losses, etc.

.Ross's move to a RWTST design for the 12 Volt radios further
complicates simulation. The 12V RWTST transformer is a hybrid between
a transmission line transformer and a conventional transformer, as it
has elements of both. It is neither fish nor fowl.

Then there is the issue of the? peculiar binocular transformer core.
Ross posted a model which treated the windings through each aperture
of the binocular as separate, non-coupling inductors. Yes, when wound
in a way which avoids linking the central post of the binocular, that
is what happens! It is key to the operation of the Stockton SWR bridge
incorporated in QMX.

More Controversy!

JZ












On Tue, Sep 26, 2023 at 1:52?PM Tony Scaminaci <tonyscam@...> wrote:
>
> Hi Hans,
>
> You make valid points, especially about modeling the output transformer. I’ll leave this question to JZ as he has more expertise in this particular area. I do think his model is fairly accurate though based on the spike and power output levels we measured early on. The spike level was close to what you and others measured on the bench.
>
> John initially suggested replacing L14 with a small value resistor on the order of 1-2 ohms as a way of eliminating the key-up spike. We also experimented with keeping L14 and using the bypass cap. Both of these alternatives resulted in eliminating the spike but I don’t recall what the effect was on power output. In this respect, you may be correct. These experiments were done with the BS170s and I took it one step further and tied the transformer directly to 12V which did result in a slight increase in power output. All of these experiments were run at ~28 MHz in an attempt to improve power output on 10 meters.
>
> At this point, I began searching for a better transistor with similar specs to the BS170 but with two notable improvements: lower Vgs threshold and higher Vds breakdown voltage. Microchip’s TN0110 is an excellent drop-in replacement for QDX radios. Simply flip them upside down and you’re in business. The 1V lower gate threshold is more suitable for a 5V drive level and the 100V minimum breakdown voltage is much more effective against the L14 spike voltage. As always, it’s best if the spike never exceeds 100V… this could be achieved by a slight reduction in L14’s inductance.
>
> The TN0110 is back in stock at Mouser. I encourage you to build a QDX with this device and compare it directly against a QDX using the BS170. You’ll be pleasantly surprised at the increased power output and your customers will experience a much lower failure rate of the PA. A win for everyone.?
>
> Regards,
>
> Tony
> AC9QY
>
>
> On Mon, Sep 25, 2023 at 12:25 AM Hans Summers <hans.summers@...> wrote:
>>
>> Hi Tony
>>
>> Real world testing, it is easy to see the clear decrease in power output and efficiency if you omit L14 (the 10 turn FT37-43 choke). The difference in performance is notable and significant. The fact that your simulation produces a different result indicates to me that something isn't quite right there. I suspect accurately simulating the output transformer may be critical, a simple coupled coil model may not suffice.
>>
>> The point about driver level is also quite interesting. Back when developing the original QCX I experimented with this. In my first prototype I had an entire ACT00 logic chip driving the three parallel BS170s with all four gates in parallel. Later I needed to implement other features in the transceiver and for some of those, taking some of the NAND gates for other purposes would be useful or necessary. I wanted an inverter for the TX signal and also to be able to gate both the CLK2 signal to the PA and the signal generator. The end result was that I only had a single gate left, to drive all three BS170 in parallel. I found that a little alarming, because there are three BS170s in parallel in QCX and they are Class E, and fast clean switching is very important. So of course then I had to decide whether to add another ACT00 chip or perhaps add something some place else to free up gates again. To make that decision I made detailed power and efficiency measurements for 1, 2, 4 gate cases. I also tried one gate per BS170 gate (3 gates used). I found that there was an increase in power output and efficiency when going from 1 gate driver to 2. But it was quite a slight small improvement. There wasn't any significant improvement in going from 2 to 4. Driving the gates one by one (one gate per BS170 separately) actually made things slightly worse; for whatever reason, paralleled gates seem to work better. Accordingly with these observations in hand, I felt happy sticking with the single gate drive for QCX. Then when it came to QDX where:
>>
>> 1. There are 2 gates per driver not one;
>> 2. There are 2 parallel transistors not 3;
>> 3. It isn't Class E so it's a little less critical;
>> I felt entirely comfortable with 2 gates driving 2 parallel BS170s on each side.
>>
>> So I haven't tried doubling up a piggy back ACT08 but it would be an interesting experiment for someone; personally it would surprise me if doubling up made a significant or even noticeable improvement.
>>
>> 73 Hans G0UPL
>>
>>
>
>





Re: Kudos to Jeff W1NC

 

You can add my first QMX kit to the list of blown MPCs.? I believe that I caused the failure by testing out of the provided enclosure.? Pressing the encoders and buttons can flex the boards if not supported correctly.? My second one works as per specifications.? I am now cautious about supporting the boards when testing outside the enclosure.? I am looking into nylon standoffs to replace the screws that hold the mainboard to the display to see if that provides better board support.

The QMX is a very dense package with very little room for error.? It is GREAT if you want portability, not so if you do not need the small size.

Hans has put a lot of capability in a tiny package with several innovations that require new methods of construction and troubleshooting.? I believe that once learned, there is a much higher success rate.? Attention to detail and parts alignment are critical for this kit.? It's not one to be your first build.? I wish there were a "shack" or "+" version that would be about three to four times the size of the current QMX.? The QCX+ is a good example.

This is only 3 of over 1,000 kits sold, so it is not a high failure rate.? We are just the unlucky ones to be in the minority.
73
Evan
AC9TU
Re: QMX Display Brightness

 

Hi Gregory,

There is a 40-watt version.??


If you already have the 100-watt base, you can look up the N7DDC GitHub or the following manual:


Specifics will have to come from others.

There is a 开云体育 for the ATU:
/g/ATU100

73
Evan
AC9TU
Re: Kudos to Jeff W1NC

 

开云体育

Ya know, blown CPU's seem to be very common on the QMX (mine was blown, too!)

Wonder why?

Paul -- AI7JR

On 9/27/23 07:01, nz0tham@... wrote:

I sent my QMX to Jeff W1NC for repair but unfortunately I managed to blow the CPU because of lousy soldering.? He is very professional and quick so if you need any QRP Labs gear repaired give him a shout - I highly recommend him.

And because I am apparently a glutton for punishment I ordered another QMX kit hoping I learned enough lessons the first time.

73, Bill NZ0T?

Re: #u3s FST4W on the U3S? #u3s

 

Good to hear that it's at least technically possible in some way... Yes, was hoping it might be, with "just" a firmware update ( I don't mean to minimize the work involved in creating a new firmware :-P )

Looks like with the GPSDO input and if you elect the TCXO module, it could be quite a nice little FST4W beacon, even up into the low HF, similar to QDX capabilities!?

W.
Re: QMX Display Brightness

 

Hey Cal -?
Tried to look you up via QRZ to ask you a question about the AT-100M.
Here it is:
For Function #10 "Calibration" what setting do you use for 20W radios such as the Xeigu G90 or FX-4CR?
It's not 10w but it's not 100W either?
Thanks
Gregory
AC1NY
Boston
Re: QMX enclosure question

 

Ok great.? Thanks for the quick answer.


On Wed, Sep 27, 2023, 18:06 mike/w1mt <w1mt.qrp@...> wrote:
The USB-C jack may create an issue and there will be no mic hole.

Nothin a dremel can't solve.

-mike/w1mt

On Wed, Sep 27, 2023 at 12:03?PM Brent Kaser <wb9uxn@...> wrote:
>
> I happen to have an extra QCX mini enclosure.? If I order a QMX will it physically fit in the mini enclosure, understanding that the silkscreening probably differs?
>
> Thanks,
> Brent WB9UXN
>





Re: QMX RX BPF troubleshooting, a new clue

 

ALL:

If I have any question regarding the Zin(fRX - fLO) characteristics, it is more on how we can take advantage of it. If that function is a steep concave, particularly at lower fLO like 3 to 10MHz range, the BPF bank can be made with a single inductor optimized for higher bands and let the mixer reject the unwanted frequency. That would be very nice. It sounds a bit too good to be true to us but it would also be a big strike against someone trying to build a high sample rate wideband receiver.
Re: QMX - What's up?

 

开云体育

I have considered removing them as a last try. I've used them in my QDXs, but there was room to build a much beefier heat sink there. Also, as I've said before, with the number of dying BS170s I've had the sockets save the board. We'll just have to take it one thing at a time.

Thanks for the hint on using low temp solder. Good idea.

73,
Cliff, AE5ZA



On Sep 27, 2023, at 08:27, Rich Brandt, AE8AA <richbrandt@...> wrote:

Thanks, Cliff, your pictures are perfect.
I still suspect poor heat removal from the BS170s.? Can't prove it from here in Michigan though.
If you decide to eliminate the sockets in the future, I suggest using low-temperature desoldering alloy to remove them.? Less chance of damaging your board.
/g/QRPLabs/topic/92402784
/g/QRPLabs/topic/97094943
/g/QRPLabs/topic/98831808
Before you install new BS170s, clean all of the weird alloy off with desoldering braid and flux.

Re: QMX enclosure question

 

The USB-C jack may create an issue and there will be no mic hole.

Nothin a dremel can't solve.

-mike/w1mt

On Wed, Sep 27, 2023 at 12:03?PM Brent Kaser <wb9uxn@...> wrote:

I happen to have an extra QCX mini enclosure. If I order a QMX will it physically fit in the mini enclosure, understanding that the silkscreening probably differs?

Thanks,
Brent WB9UXN
QMX enclosure question

 

I happen to have an extra QCX mini enclosure.? If I order a QMX will it physically fit in the mini enclosure, understanding that the silkscreening probably differs?

Thanks,
Brent WB9UXN
Re: mute QDX - update

 

All,

Well now there's a thing.

Rx is now fine - original fault ????

Tx, is FUBAR!

I know why but not why.

In Rx there is a nice signal on the Clk0 & Clk1 lines at the Rx frequency and they are 90 Degrees apart.

On Tx then the frequency on those lines doubles! i.e. if 40M set then 15-ish MHz is seen. They are correctly phased on the gates of the FETs (removed but looks like I didn't need to).

If I run a sweep the Clk0 & Clk1 sweep across the frequency band set but Clk2 is ~2F

That's not right!

A reload of the firmware & factory reset results in the same result!

That explains the sweeps - all well out of range as Clk2 is also 2F not F.

Ideas - Hans?

Regards & thanks for the help

Nick
M0HGU
--
What your soldier wants - really, really wants - is no-one shooting
back at him. (alt.fan.pratchett)
Wed 10984 Sep 16:40:02 BST 1993
16:40:02 up 3 days, 23:37, 8 users, load average: 0.74, 0.38, 0.39



--
73 Nick M0HGU
Re: QMX RX BPF troubleshooting, a new clue

 

JZ, I totally understand your concern, but as far as I'm concerned, that is a non-issue until it is proven to be a problem. It is probably a minor factor in the mess, but it is not the dominant factor as far as I see. You can't get distracted by minor factors and lose sight of the dominant factors... that's probably why a lot of people believe RF is too much voodoo and little theory.

The BPFs are low Q because (1) they are designed that way, and (2) the interaction with the TX LPF's reactance curve makes the BPF even wider passband by partially undoing the series resonance. I thought I explained above. My posts were chronological and they might have taken people to a mini tour to my experimental journey, which I know can be mentally tiring a bit. I can rewrite more clearly after the whole job is done.

As you see in my traces with (1) my finger on the LPF, dampening/detuning the filter operation, and (2) shunt resistor, dampening the LPF impedance swing both show the BPF response close to theoretical one. If you saw a significant deviation there, you would next look into the next suspicious element down on the list, but I'm totally satisfied with those filter responses for a practical transceiver. I only wish we could easily decouple the LPF and BPF on this very tight board space. Without doing something about this LPF-BPF interaction, doing something about the detector impedance will not improve the BPF operation to any appreciable level.
QDX availability

 

QRP Labs ordering web page still shows?

QDX boards ran out and we are waiting on a new batch; your order will not be shipped until around 11-Sep-2023 (estimated).

I have not been following the recently and a quick search of postings did not provide and answer.

Are QDX kits shipping again or is there still a wait for QDX boards?

cheers, Graham ve3gtc
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