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Re: #qmx Power supplies and the measured PWM #qmx

 

Hi,
a question to Hans:
What if the PCB #2 SMPS card is not present (or is faulty)? So the ADC 3V3 signal line would be open.
Does the FW algorithm let the 3V3 linear regulator work for VDD instead?
And does the LDO in this case withstand the constant dissipation?

In other words, if one decides to operate the 3V3 rail from a linear regulator or to just troubleshoot using this option (without the PCB #2), would it be enough to ground the ADC 3V3 line on the connector?

73 Bojan S53DZ
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

Nick,

The Tayloe circuit is incredibly robust, tolerating all manner of
egregious sins! It also possesses its own intrinsic BPF property. I
would give your idea a try. We might all be pleasantly surprised by
the RX performance.

JZ

On Thu, Aug 17, 2023 at 12:07?PM Nick G4IKZ via groups.io
<nds12321@...> wrote:

I agree. And even if this worked out it would only give significant attenuation for signals around the medium wave AM broadcast bands. For anything else it's just going to be few dB. But how else do we avoid NF degradation when sharing simple BPFs for the high bands? Any transmit-only WSPR guys might not mind poor Rx NF. So for them a 7-band Tx might still be good fun. But those wanting 7-band Rx might not be so happy.
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

Pawe?,

This is tricky business!

Since Han's designs use the Tayloe circuit as a downconverter to an
IF, and not as a direct conversion to baseband detector, the input
impedance of that circuit at the receive frequency is somewhere
between its extremes, and rather unknown.
Maybe I should stop referring to it as a detector and call it a downconverter?

Are those zero ohm resistors in your schematics?

Dobry dzie¨½ 73
JZ KJ4A

On Thu, Aug 17, 2023 at 12:02?PM Pawe? H <pawel@...> wrote:

I also wonder why QDX/QSX are missing some kind of matching. In many amateur designs using that kind of mixer there is usually a matching to 50 Ohm (see example attached, Polish transceiver Husarek). I am sure the matching keeps filters characteristic as designed, maybe even helps with the parasitic resonances.
It is worth to check one day.

73
Pawe? SO8FM.
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

I agree. And even if this worked out it would only give significant attenuation for signals around the medium wave AM broadcast bands. For anything else it's just going to be few dB. But how else do we avoid NF degradation when sharing simple BPFs for the high bands? Any transmit-only WSPR guys might not mind poor Rx NF. So for them a 7-band Tx might still be good fun.? But those wanting 7-band Rx might not be so happy.
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

I also wonder why QDX/QSX are missing some kind of matching. In many amateur designs using that kind of mixer there is usually a matching to 50 Ohm (see example attached, Polish transceiver Husarek). I am sure the matching keeps filters characteristic as designed, maybe even helps with the parasitic resonances.
It is worth to check one day.

73
Pawe? SO8FM.
Re: QMX and FT8CN audio issue - strange issue

 

Hi Pawel,

I have never had to adjust the threshold on any of the QDX transceivers I have built (I only run FT8).
The one I was testing below was running 1.10 firmware.
This problem is very puzzling.
The audio stream is completely digital and gain is set to full scale (according to the slider positions).
For me, at least, it only occurs with the combination of QMX/FT8CN.
QMX/WSJT-X works fine.

73, Mike KK7ER
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

One more thing, Nick:

Because the mux switches you will use to selectively ground the
inductors have their parasitic capacitance, you may still see some
unplanned strange resonances. Hopefully they won't matter. TANSTAAFL,
as the saying goes!
JZ

On Thu, Aug 17, 2023 at 10:53?AM John Zbrozek <jdzbrozek@...> wrote:

I'm very eager to see how that works out, Nick!
Good luck!...JZ KJ4A

On Thu, Aug 17, 2023 at 10:52?AM Nick G4IKZ via groups.io
<nds12321@...> wrote:

I agree that the roll-off of a 2-element HPF isn't great. But as frequency gets lower a given dB/octave equates to more dB/MHz. So I think a switched HPF might still be a good way to keep the high-power broadcasters out of the mixer.

Regarding cost I wasn't thinking about extra hardware - just a reconfiguration of the switched C and switched L that are already present. Hopefully just a bit of track-cutting and rewiring to turn the existing switchable bandpass filter in to a switchable high-pass filter.
Re: QMX dead

 



The schematics are on the QMX page along with the Assembly manual and the Operating manual.

Ken, W4KAC
Re: #QMX kit shipments caught up #qmx

 

Hans,

Great job!

Thanks to you and your team for all of their efforts.

Looking forward to receiving my two new toys (QMX's) in the upcoming months.

Kind regards,
Rhett KB4HG


On Thu, Aug 17, 2023 at 6:42?AM Hans Summers <hans.summers@...> wrote:
Hi all

We have caught up on all pending QMX shipments. Henceforth all QMX kits will be shipped within 1 business day like all the other in-stock kits.?

Assembled radios, the list is still long, but at 690 orders now compared to reaching a peak of 778 some months ago. Current team size is 10 trying to deal with it.??

73 Hans G0UPL
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

I'm very eager to see how that works out, Nick!
Good luck!...JZ KJ4A

On Thu, Aug 17, 2023 at 10:52?AM Nick G4IKZ via groups.io
<nds12321@...> wrote:

I agree that the roll-off of a 2-element HPF isn't great. But as frequency gets lower a given dB/octave equates to more dB/MHz. So I think a switched HPF might still be a good way to keep the high-power broadcasters out of the mixer.

Regarding cost I wasn't thinking about extra hardware - just a reconfiguration of the switched C and switched L that are already present. Hopefully just a bit of track-cutting and rewiring to turn the existing switchable bandpass filter in to a switchable high-pass filter.
Re: QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m] #qmx

 

I agree that the roll-off of a 2-element HPF isn't great. But as frequency gets lower a given dB/octave equates to more dB/MHz. So I think a switched HPF might still be a good way to keep the high-power broadcasters out of the mixer.

Regarding cost I wasn't thinking about extra hardware - just a reconfiguration of the switched C and switched L that are already present. Hopefully just a bit of track-cutting and rewiring to turn the existing switchable bandpass filter in to a switchable high-pass filter.
Re: QMX dead

 

I tried to post a link for the schematic but it does not work...grrr! There is a link on this forum which produce great if not faint diagrams. Another on the same thread "QMX schematics" found a way to make the traces more bold. Try the search above with QMX schematic and see whatcha get.

73
Karl
Re: Fldigi and QMX successful???

 

I'm just getting to wringing out the QMX after overcoming a few assembly issues.? It is NOT working here with fldigi 4.1.20 under Windows 10.?

Using flrig as a TS-480SAT, it's working fine with JS8Call.? Nothing particularly odd there that I haven't seen with the QDX.? Same setup with fldigi, I don't get sufficient audio out and, consequently, to power output.? On TX, the QMX's transmit indicator under the VFO indicator is two dots, indicating PTT activated and insufficient audio drive.? RX is good.

I've double checked audio device settings - they're the same here as with another rig with an internal, USB sound device - and twiddled Windows' exclusive access selections for sound devices to no effect.

Haven't figured it out, yet.? What are you seeing?

? Dan
? N7SHM
Re: QMX - 80, 30, & 20M Dead

 

That's pretty cool.? Thanks for sharing, Timothy.
Re: QMX RF sweeps

 

Mike,
I think Karl is asking whether all the holes are tested to prove that
they are plated all the way through.
Fixturing for that can be done, but it does cost a bit.
That said, I think his problem is probably elsewhere.

JZ KJ4A

On Thu, Aug 17, 2023 at 10:05?AM mike/w1mt <w1mt.qrp@...> wrote:

Then the answer is yes it did work except for the 80/20 issue.

I will say that 90% or more of the issues I have and see with others
are with the toroids and soldering issues with them.

The description of the 6 layer pcb starts at page 5 of the assembly
manual. I interpret it as saying that all holes are through plated.

-mike/w1mt

On Thu, Aug 17, 2023 at 9:54?AM Karl via groups.io
<karlshumaker@...> wrote:

What I am asking is was this model actually tested before it was "released" as a kit? Aside from some error I undoubtedly made that causes my receiver not to receive, would this thing have worked in the first place? I think the answer is yes since others have had first power up success...or so it seems. The question is prompted by the radical difference of L401.

The puzzling thing that nags me is there is so much that is working so right from the beginning. Mostly because I have studied this forum to avoid the pitfalls found by others. Things like the drain shorts on the PS boards. The encoder shell contacting the power receptacle and getting the wrong component in the right place.

The biggie is the soldering technique requiring a differnt tool. The right tool was easy and then so was the soldering.

Are ALL the through holes plated ALL the way? Grasping at straw...!s here
Re: QMX RF sweeps

 

Then the answer is yes it did work except for the 80/20 issue.

I will say that 90% or more of the issues I have and see with others
are with the toroids and soldering issues with them.

The description of the 6 layer pcb starts at page 5 of the assembly
manual. I interpret it as saying that all holes are through plated.

-mike/w1mt

On Thu, Aug 17, 2023 at 9:54?AM Karl via groups.io
<karlshumaker@...> wrote:

What I am asking is was this model actually tested before it was "released" as a kit? Aside from some error I undoubtedly made that causes my receiver not to receive, would this thing have worked in the first place? I think the answer is yes since others have had first power up success...or so it seems. The question is prompted by the radical difference of L401.

The puzzling thing that nags me is there is so much that is working so right from the beginning. Mostly because I have studied this forum to avoid the pitfalls found by others. Things like the drain shorts on the PS boards. The encoder shell contacting the power receptacle and getting the wrong component in the right place.

The biggie is the soldering technique requiring a differnt tool. The right tool was easy and then so was the soldering.

Are ALL the through holes plated ALL the way? Grasping at straw...!s here
Re: Stripping enamel insulation off of magnet wire & Rotary Magnet Wire Strippers

 

I know what follows helps no one today unless you come across some 50 years old enameled wire... We'd simply hold the tip of the wire in an open flame for just a moment then quickly plunge it (the wire not the flame) into a thimble size amount of alcohol and POOF! The enamel would shatter into the alcohol leaving behind a pristine copper wire. It was an old QST suggestion which worked very well back then. Today however, "enameled" wire isn't enameled but coated with polymers that don't succumb to the old technique.
--
Glen - KE7FD
Re: #QMX kit shipments caught up #qmx

 

Good going!
Getting a small business running smoothly is not easy but is rewarding.
Chris
Re: QMX RF sweeps

 

What I am asking is was this model actually tested before it was "released" as a kit? Aside from some error I undoubtedly made that causes my receiver not to receive, would this thing have worked in the first place? I think the answer is yes since others have had first power up success...or so it seems. The question is prompted by the radical difference of L401.

The puzzling thing that nags me is there is so much that is working so right from the beginning. Mostly because I have studied this forum to avoid the pitfalls found by others. Things like the drain shorts on the PS boards. The encoder shell contacting the power receptacle and getting the wrong component in the right place.

The biggie is the soldering technique requiring a differnt tool. The right tool was easy and then so was the soldering.

Are ALL the through holes plated ALL the way? Grasping at straw...!s here
Re: #qmx Current consumption varies on wide range #qmx

 

Under the Terminal/Diagnostics Are you getting a Transmit Voltage showing Q507 is being turned on.
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