QMX Menu Suggestions

#108855

Hans, here are a couple of minor suggestions from the Operations Manual.

4.6 - Frequency Presets - Why not have CANCEL be the EXIT button (rather than the right rotary button) and LOAD be the right rotary button? That would make it more intuitive with the usual function of the EXIT button?and consistent with the Messages selection buttons. I realize that this is currently consistent with the QCX, but I never liked it there either as I usually ended up cancelling rather than loading! I just didn't say anything.

5.14 - Clock Setting - Is there any way to set the clock manually? Might be nice to do, so I don't have to use another device to log QSOs? I normally log on paper and don't drag a GPS unit along for SOTA.

? ? ? ? - Backlight setting - Should be a way to turn the backlight on temporarily for 5 seconds or so, by single button pushes. Along the same lines, it would be nice to have a third setting that normally has the backlight off, but automatically turns the backlight on for 5 seconds or so whenever a button is pressed or an encoder turned (but not when paddles or key are pressed). Don't know that you need both of these things - the latter would work just fine.

5.17 - Factory Reset - Suggest putting the 'Enter 17' system (from QCX) back in place. Although I haven't done it, it would just be too easy to accidentally press the encoder button when you meant to turn it.

--
73, Dan? NM3A

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108854

Hello Devan

A technique I suggested for QCX troubleshooting was to bypass the signal generator resistor (120K in QCX, 100K R518 in QMX) with a much smaller resistor, say 330-ohms. Then the signals are enough amplitude that you can trace them through the LPF, BPF and trifilar transformer, with an oscilloscope. Signal tracing, oldest techniques, still valid. I don't think there's a problem in your PCM1804 or digital Signal processing. I'd guess it's in the filters or mixer.

73 Hans G0UPL

Show quoted text

On Wed, Aug 30, 2023, 7:17 PM Devan Phillis <devan@...> wrote:

Hans,

The trifiliar was one of the first things we did…. Also, I reflowed all the other places where enamel comes thru the board. I should mention that the 1804 gets warm… not hot but warm. I’ll look back try my emails with John and get an idea of where we were, it has been a while since I had the time to mess with it. I would really like to get the original going because it was one from Dayton and then the new one is obviously not. Also… I made a work around but a heads up, my 2X3 female socket connector was missing a pin. See attachment.

Re: CAT port returns ` ` ` on QCXmini

#108853

Thanks, I'll try that as well.

-Jerry AC5JM

On Wednesday, August 30, 2023 at 09:16:16 AM CDT, Chuck - K3FLN via groups.io <chuck.salmon@...> wrote:

Putty can be configured to wait for carriage return to send message.? Just set "local line editing" and "local echo" to "force on"?in the terminal options.

--
Cheers,
Chuck

Re: CAT port returns ` ` ` on QCXmini

#108852

I have a TTL to RS232 converter that was designed to interface directly with Raspberry Pie I/O pins that I will try and let you know.? It should also work in reverse to convert RS232 to TTL.??

Thanks!

Jerry AC5JM

On Wednesday, August 30, 2023 at 08:21:31 AM CDT, Rob Giuliano via groups.io <kb8rco@...> wrote:

On Tue, Aug 29, 2023 at 03:56 PM, David Markovitch wrote:

Besides having higher voltages, a USB to RS232 signal will be inverted compared with a RS232 TTL signal.

Not to mention that TRUE RS232 levels swing + and - at those higher voltages.? So your 6V RS232 logic is very likely switching between +6V and -6V.
There is a good explanation here:??of?

-------
Rob KB8RCO

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108851

Hans,

The trifiliar was one of the first things we did…. Also, I reflowed all the other places where enamel comes thru the board. I should mention that the 1804 gets warm… not hot but warm. I’ll look back try my emails with John and get an idea of where we were, it has been a while since I had the time to mess with it. I would really like to get the original going because it was one from Dayton and then the new one is obviously not. Also… I made a work around but a heads up, my 2X3 female socket connector was missing a pin. See attachment.

Re: #qmx QMX and waste heat from the finals #qmx

#108850

开云体育

Wayne,

I had it lying around from a Raspberry Pi 3B that I had put in a different enclosure with different cooling so the heat sink wasn't needed anymore. Wish I had more of them.

73,

Cliff, AE5ZA

Show quoted text

On Aug 30, 2023, at 10:55, Wayne Greene <wayne.greene489@...> wrote:

Thanks, Cliff. You've been a tremendous help on this. Where did you find the heat sink you have on top of the finals?

Wayne KB4DSF

On Wed, Aug 30, 2023 at 11:41?AM Cliff <ae5zaham@...> wrote:
Wayne,

There is just a hole through the plate to hold it in place and a foot that you can't see almost at the left hand edge under the plate the same as the one that is visible on the right hand side. It was made from a piece of aluminum molding that happened to have those two feet in the right place. I may try to put a piece of it under the finals on the QMX, but without the feet, as I'm sure there isn't enough room for the extra height of the feet.

I also added the diode across L14 so hopefully it will be as bullet proof as I can make it and baring operator "destructive" testing should last a long time.

Here's the reference from John Z to the diode "fix" in case you are interested.

The diode simply is in parallel with the 47uH inductor L14, with the
orientation shown in the photo provided by Paul W9AC. Cathode towards
the power supply connection, anode to the transformer center tap.
Any of the diodes he mentioned ?(1N4448, 1N4148, 1N914) will do a fine
job of absorbing the end-of-transmission voltage spike it produces.
I have used a 1N914.

/g/QRPLabs/message/105256

73,
Cliff, AE5ZA

On Aug 30, 2023, at 09:35, Wayne Greene <wayne.greene489@...> wrote:

Hey, Cliff. How did you mount the plate under your finals?

Wayne KB4DSF

--?
Wayne Greene

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108849

Hello Devan

The fact that it has noise along there, not flat-lined, indicates to me that the PCM1804 is probably OK. You probably have an issue upstream of that. Could even be toroid enamel... or mixed up windings on the trifilar transformer. But my apologies if you have considered this already.?

73 Hans G0UPL

Show quoted text

On Wed, Aug 30, 2023 at 6:57?PM Devan Phillis <devan@...> wrote:

Audio Filter Sweeps

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108848

RF Filter Sweeps

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108847

Image Sweeps

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108846

Audio Filter Sweeps

Re: #qmx QMX and waste heat from the finals #qmx

#108845

Thanks, Cliff. You've been a tremendous help on this. Where did you find the heat sink you have on top of the finals?

Wayne KB4DSF

Show quoted text

On Wed, Aug 30, 2023 at 11:41?AM Cliff <ae5zaham@...> wrote:

Wayne,

There is just a hole through the plate to hold it in place and a foot that you can't see almost at the left hand edge under the plate the same as the one that is visible on the right hand side. It was made from a piece of aluminum molding that happened to have those two feet in the right place. I may try to put a piece of it under the finals on the QMX, but without the feet, as I'm sure there isn't enough room for the extra height of the feet.

I also added the diode across L14 so hopefully it will be as bullet proof as I can make it and baring operator "destructive" testing should last a long time.

Here's the reference from John Z to the diode "fix" in case you are interested.

The diode simply is in parallel with the 47uH inductor L14, with the
orientation shown in the photo provided by Paul W9AC. Cathode towards
the power supply connection, anode to the transformer center tap.
Any of the diodes he mentioned ?(1N4448, 1N4148, 1N914) will do a fine
job of absorbing the end-of-transmission voltage spike it produces.
I have used a 1N914.

/g/QRPLabs/message/105256

73,
Cliff, AE5ZA

On Aug 30, 2023, at 09:35, Wayne Greene <wayne.greene489@...> wrote:

Hey, Cliff. How did you mount the plate under your finals?

Wayne KB4DSF

--

Wayne Greene

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108844

Hans,?

The sweeps were terrible. And I have no audio out of the 1st QMX. I worked with John Zbrozek a good bit with the 1st unit and we got it that far and we decided that the PCM1804 was likely bad. I went looking for a replacement and found several models on digikey or Newark (one of the two) but was unsure which to purchase. No you hadn’t missed replying before… I did however try to send you a private message on here a while back and I’m not sure if it ever even went…?

Cliff,

I did try swapping power boards from the old unit one at a time to the new. My old 5v board and my new 3v board allowed me to get the unit powered up to apply firmware, but now it will not power up again. Swapping the power boards every which way gives me no change now. And putting the old boards back into the old QMX sends it back to the way it was this morning when started…. I’m pretty confused haha.

Thanks,
Devan KD8MST

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108843

开云体育

Have you tried the power boards one at a time from the old unit that does power up in the new QMX?

73,

Cliff, AE5ZA

Show quoted text

On Aug 30, 2023, at 09:46, Devan Phillis <devan@...> wrote:

Good morning,

I have received and built my second QMX according to the current build guide, and cannot get it to power on. I built it for 12v operation and I tried starting at 7v and then up to 10v (painful past experience). I know the screen will be blank and off until the FW is loaded. The unit does not even power on enough to be recognized as a USB device. I tried reflowing all of my connections on the main board as well as the connections on the buck converter boards and I even reflowed the USB port.?

My first QMX had a bad day from the word go (fed with almost 14v by accident), and it will power on now after many repairs and much troubleshooting, but has no RX, I believe I may have fried one or more of the of the a/d converters on the main board but I do not know what part to replace them with, there are too many options. Maybe Hans can speak to that?

Thanks,
Devan KD8MST

Re: #qmx QMX and waste heat from the finals #qmx

#108842

开云体育

Wayne,

There is just a hole through the plate to hold it in place and a foot that you can't see almost at the left hand edge under the plate the same as the one that is visible on the right hand side. It was made from a piece of aluminum molding that happened to have those two feet in the right place. I may try to put a piece of it under the finals on the QMX, but without the feet, as I'm sure there isn't enough room for the extra height of the feet.

I also added the diode across L14 so hopefully it will be as bullet proof as I can make it and baring operator "destructive" testing should last a long time.

Here's the reference from John Z to the diode "fix" in case you are interested.

The diode simply is in parallel with the 47uH inductor L14, with the
orientation shown in the photo provided by Paul W9AC. Cathode towards
the power supply connection, anode to the transformer center tap.
Any of the diodes he mentioned ?(1N4448, 1N4148, 1N914) will do a fine
job of absorbing the end-of-transmission voltage spike it produces.
I have used a 1N914.

/g/QRPLabs/message/105256

73,

Cliff, AE5ZA

Show quoted text

On Aug 30, 2023, at 09:35, Wayne Greene <wayne.greene489@...> wrote:

Hey, Cliff. How did you mount the plate under your finals?

Wayne KB4DSF

Re: #qmx QMX and waste heat from the finals #qmx

#108841

The BS170 (finals) are low power devices with a thermal impedance of 150C/W.? Trying to reduce the internal chip temperature by lowering the already low external thermal impedance is pretty futile.?
(thermal impedances add together just like electrical impedance).
So imagine a bad SWR causing the dissipation in the four finals to dissipate 2W, 0.5W each, then the rise within the transistor will be 75C.? If you find the mounting surface feels painfully hot to touch (cannot keep a finger on it) then it is 44C only a rise of 15C to 20C over the case temperature - a fraction of the transistors internal temperature rise.?
Someone can take the time to do the thermal modeling, its quite simple.

Re: 2nd QMX Build and it wont power on and an update on my old unit...

#108840

Hello Devan

There's only one ADC on the main board which is the PCM1804. But I'd suggest first checking what you see on the RF sweeps (apologies if you've already posted that here, too many topics to follow).?

73 Hans G0UPL

Show quoted text

On Wed, Aug 30, 2023 at 5:46?PM Devan Phillis <devan@...> wrote:

Good morning,

I have received and built my second QMX according to the current build guide, and cannot get it to power on. I built it for 12v operation and I tried starting at 7v and then up to 10v (painful past experience). I know the screen will be blank and off until the FW is loaded. The unit does not even power on enough to be recognized as a USB device. I tried reflowing all of my connections on the main board as well as the connections on the buck converter boards and I even reflowed the USB port.?

My first QMX had a bad day from the word go (fed with almost 14v by accident), and it will power on now after many repairs and much troubleshooting, but has no RX, I believe I may have fried one or more of the of the a/d converters on the main board but I do not know what part to replace them with, there are too many options. Maybe Hans can speak to that?

Thanks,
Devan KD8MST

Re: QMX - sockets for BS170s

#108839

开云体育

So I think the discussion about pin headers for the PA transistors is adventurous. The most important point with all devices QCX, QDX and now QMX is absolutely the use of a tuner. The antenna needs to be adjusted. This has now been cleverly solved with the QDX with the SWR bridge. The QMX will not work without an adapted antenna.

Of course, if you do WSPR with 12V or even 13.8V with the QCX or QDX, you damage the device and yourself.

?

Yesterday I did FT8 with the QMX for about an hour, with 12V. You could no longer touch the device because it was too hot. It didn't do him any harm. So use thermal paste. Then the PA transistors have a low thermal resistance and everything is chic.

?

73 Reinhard DL3AS

?

Von: [email protected] [mailto:[email protected]] Im Auftrag von Cliff
Gesendet: Mittwoch, 30. August 2023 13:52
An: [email protected]
Betreff: Re: [QRPLabs] QMX - sockets for BS170s

?

The sockets work out great on the QDX. I'm about to try them on a QMX so can't say how that works. Space may be tight.

?

73,

Cliff, AE5ZA

?

Show quoted text

On Aug 30, 2023, at 05:54, Graham Whaley <graham.whaley@...> wrote:
?
Aha, I knew I'd seen a photo with pin headers under the BS170's recently - check out the picture of the heatsinking on message /g/QRPLabs/message/108109
Might want to ask Cliff, AE5ZA how that is working out ;-)
?
Graham, M7GRW
?
On Wed, 30 Aug 2023 at 11:40, Jerry <Jerryh47@...> wrote:
After repairs done multiple times replacing FET Q9 in my QDX transceivers the pads are getting “tired.” ?I used some small brass tube stock (~1 mm outer diameter) to make eyelets or grommets to reinforce the pads. A short length of the tubing goes through the pad and is swaged with a center punch on both sides of the PCB. They are not sockets but do strengthen the pads so the pads don’t lift off the board so easily after several soldering cycles.?
?
?

?

2nd QMX Build and it wont power on and an update on my old unit...

#108838

Good morning,

I have received and built my second QMX according to the current build guide, and cannot get it to power on. I built it for 12v operation and I tried starting at 7v and then up to 10v (painful past experience). I know the screen will be blank and off until the FW is loaded. The unit does not even power on enough to be recognized as a USB device. I tried reflowing all of my connections on the main board as well as the connections on the buck converter boards and I even reflowed the USB port.?

My first QMX had a bad day from the word go (fed with almost 14v by accident), and it will power on now after many repairs and much troubleshooting, but has no RX, I believe I may have fried one or more of the of the a/d converters on the main board but I do not know what part to replace them with, there are too many options. Maybe Hans can speak to that?

Thanks,
Devan KD8MST

Re: QMX -- first try, first problems (bad sweeps, no output power)

#108837

Adam via groups.io <qrp-labs@...> wrote:

I have several issues with it. Two are serious, other are minor.Nevermind. I had short on an RF port.

Re: QMX: Kit Build complete - My observations

#108836

Hi Bojan

?

Everything went well. Then I assembled the rest. Nice beast.

Awesome

?

And yes Hans, if you don't know already, there is really really no place left on that board. What were you thinking? Haha.

Well it was all about romance. Marriage. Of QDX and QCX-mini. For whatever reason, I was determined to make it all fit in the same enclosure as QCX-mini. And use through-hole capacitors in the filters so we can have different band-coverage versions, like QDX, just by choice of supplied components. The mechanical design was going to be more like QCX-mini and the electronic design more like QDX (plus extras). Ask my XYL, she says I'm the most obstinate thing she's ever known (and as often as not, wishes she didn't). Of course, I disagree. But then again I did absolutely refuse to back down from my fixed PCB size, to fit in the QCX-mini enclosure. And when there still wasn't space in the building... well I just put in another floor (the SMPS floor!).?

73 Hans G0UPL