Date   

QCX+hardware

Gene O <eaopa@...>
 

Has anyone had a problem with the nylon hardware not being strong enough?  It seems when I press the TUNE button it tends to flex the two PC boards mounted on the front panel.  This occurred several times and on one occasion there appeared a "G" in the display.  The unit would not function until I shut the power off and then on again.  Now all seems to be OK.

The unit was factory made.

Has anyone changed the nylon hardware to stainless steel?  Would this cause a short somewhere?

Any help would be appreciated. Thanks.

Gene, W2BXR


Unit won't power up - #40m #qcxmini

Robert N0QLR
 

Good evening, I wanted to reach out to the group and see if anyone had a similar experience, or could give me some initial troubleshooting direction. I went to send a message this evening, and when I got about half way through the CQ sequence, the QCXMini restarted. I was concerned about SWR and thought maybe I hadn't tuned for the frequency, so I checked SWR and was at 1.4. So, I tried sending again, and it shut down totally, the display flickered, then went dark. Now, it's not powering on at all. 

Any suggestions?


Re: LightAPRS-W Programming Error #kph #lightaprs

Andrew Blessing
 

I exchanged emails with Mustafa and was able to get the issue resolved.

I was seeing a series error messages when attempting the sketch:

avrdude: stk500v2_getsync(): timeout communicating with programmer avrdude: stk500v2_ReceiveMessage(): timeout avrdude: stk500v2_ReceiveMessage(): timeout An error occurred while uploading the sketch

Once I set the bootloader to UART0, everything worked fine.


Re: A toroid winding question

Colin Kaminski
 

What band are you building?

Colin
K6JTH

On Sun, Mar 27, 2022 at 7:12 PM Keith AG5GW <islandpiper51@...> wrote:
I must have missed something.  I wound the first coil, T1,  with the wire bundle which was loose in the bag. I've now reached the point of winding L4.  Should I use the same wire for that job? or should I use the small coil of wire that is in the mini-bag with the several really small, yellow color toroids?  Would it make a difference? Intuition tells me that the small coil in the mini-bag may not do all the remaining coils.  Your advice is golden.  Many thanks!   


A toroid winding question

Keith "Al" AG5GW
 

I must have missed something.  I wound the first coil, T1,  with the wire bundle which was loose in the bag. I've now reached the point of winding L4.  Should I use the same wire for that job? or should I use the small coil of wire that is in the mini-bag with the several really small, yellow color toroids?  Would it make a difference? Intuition tells me that the small coil in the mini-bag may not do all the remaining coils.  Your advice is golden.  Many thanks!   


Re: My new QCX+ Desk Stand

William Smith
 

Nice! Publish it on Thingiverse, you'll be amazed how many people like and/or download it.

73, Willie N1JBJ

On Mar 27, 2022, at 7:59 PM, Colin Kaminski <colinskaminski@...> wrote:

Rev .3 this works much better it is lower and keeps its balance during button pushes .stl file available upon request.<608089F3-65A9-4D53-AFB0-75209B2B6878.jpeg><76A380E4-AFE2-4DA5-B7F7-8249753832EC.jpeg>

<17042A19-127B-4DCA-8DBF-EBEAF172CCBA.jpeg>


Re: My new QCX+ Desk Stand

Colin Kaminski
 

Rev .3  this works much better  it is lower and keeps its balance during button pushes  .stl file available upon request.


Re: QCX-Mini Display Issue

Mont Pierce KM6WT
 

On Sun, Mar 27, 2022 at 11:22 AM, Ernie Bailey - N2DGQ wrote:
While looking at the schematic for IC2 pin connectivity, do I assume for example pin #2 says "LCD D4" assume that pins goes to Display pin #4?  And pin #3 says "LCD D5", assuming connects to Display pin #5?  So on and so forth for all IC2 pins with designations of LCD. 
Hi Ernie,

Actually it's a bit simpler then that, and no assuming necessary.

It's a common practice when a schematic gets busy with lots of lines connecting different components to shorten the line to a short stub and "Label" it.   Anytime you see a schematic line stop with a label name, you can look for that label name throughout the schematic. 

I actually like the QCX+ Black&White Hi-Res schematics Hans added to the QCX+ page.  It's easier for my eyes to see... 

And since ALL QCXs, although they don't share the same "physical" layout, the do follow the same basic schematics, these image are very helpful. 

The following links can also be found on the QRP-Labs QCX+ webpage (click here).
Just above the bold "Firmware" heading.


Click Here for Main board schematics
Click Here for Display board schematics
Click Here for combined two page pdf with both the above schematics.


On the Display board schematics, you will see:


        



These labels match exactly the labels on the Main board schematics next to the processor:


         


73
km6wt


Re: QCX-Mini Display Issue

Ronald Taylor
 

Oops. Try that again ... LCD4- IC2 pin 2 to LCD pin 11
LCD D5 - IC2 pin 3 to LCD pin 12
LCD6 - IC2 pin 4 to LCD pin 13
LCD 7 - IC2 poin 5 to LCD pin 14
LCD EN - IC2 pin 6 to LCD pin 6
Hope that helps ... Ron

On Sun, Mar 27, 2022 at 12:38 PM Ron Taylor <wa7gil@...> wrote:
Ernie, sorry I just got back from Church and lunch. Alan is correct. I keep an old copy of the QCX Classic schematic around because it has the LCD pinout on the same page. Easier for me to figure it out. 

Function       IC2 pin       LCD pin
LCD D4

On Sun, Mar 27, 2022 at 12:16 PM Alan G4ZFQ <alan4alan@...> wrote:
On 27/03/2022 18:22, Ernie Bailey - N2DGQ wrote:
> All connections go to the blue line on the schematic.

Ernie,

This just represents a bundle of wires. A harness.

 >While looking at the schematic for IC2 pin connectivity, do I assume
for example pin #2 says "LCD D4" assume that pins goes to Display pin
#4?  And pin #3 says "LCD D5", assuming connects to Display pin #5?

Pin 2 enters this harness as LCD D4, and comes out with the same
designation going to LCD pin 11. (DB4) Just go round the blue line
looking for matches.

(Watch out, on a few occasions a connection may go to two places.)

73 Alan G4ZFQ







Re: QCX-Mini Display Issue

Ronald Taylor
 

Ernie, sorry I just got back from Church and lunch. Alan is correct. I keep an old copy of the QCX Classic schematic around because it has the LCD pinout on the same page. Easier for me to figure it out. 

Function       IC2 pin       LCD pin
LCD D4

On Sun, Mar 27, 2022 at 12:16 PM Alan G4ZFQ <alan4alan@...> wrote:
On 27/03/2022 18:22, Ernie Bailey - N2DGQ wrote:
> All connections go to the blue line on the schematic.

Ernie,

This just represents a bundle of wires. A harness.

 >While looking at the schematic for IC2 pin connectivity, do I assume
for example pin #2 says "LCD D4" assume that pins goes to Display pin
#4?  And pin #3 says "LCD D5", assuming connects to Display pin #5?

Pin 2 enters this harness as LCD D4, and comes out with the same
designation going to LCD pin 11. (DB4) Just go round the blue line
looking for matches.

(Watch out, on a few occasions a connection may go to two places.)

73 Alan G4ZFQ







Re: Measuring current for setting PA50 bias

Doug Perkins
 

Thanks Reg for the helpful info.  I was able to detect the current and set the bias. Thanks for the help!
Doug

 


Re: QCX-Mini Display Issue

Alan G4ZFQ
 

On 27/03/2022 18:22, Ernie Bailey - N2DGQ wrote:
All connections go to the blue line on the schematic.
Ernie,

This just represents a bundle of wires. A harness.

While looking at the schematic for IC2 pin connectivity, do I assume
for example pin #2 says "LCD D4" assume that pins goes to Display pin #4? And pin #3 says "LCD D5", assuming connects to Display pin #5?

Pin 2 enters this harness as LCD D4, and comes out with the same designation going to LCD pin 11. (DB4) Just go round the blue line looking for matches.

(Watch out, on a few occasions a connection may go to two places.)

73 Alan G4ZFQ


Re: Adjust Q1 bias on U3S - Having difficulty #bias #u3s

John Baines
 

Hi all,

I adjusted my bias by connecting an absorption wattmeter to the U3S output and increasing the bias to give 100mW output.

100mW is enough for my WSPR requirements and gives a greater factor of safety - it has survived transmitting to an open circuit.

73/72
John
M0JBA

On 27 Mar 2022, at 18:24, Nick Garrod via groups.io <gw6jhk@...> wrote:

The 0.2W that you are seeing in the reports is coded in your transmission and has absolutely no relation to your actual output power, but is dependent on what figure you entered when setting it up. 


Hans details two methods of setting the bias in the instructions, this is his preferred method. 


An alternative adjustment procedure also works very nicely. I recommend this method, if you have access to a means to measure the current consumption of the kit with reasonable accuracy. You should measure the overall current consumption of the U3S kit in “idle” mode (key up, not transmitting). You do not even need to plug in the Si5351A module for this. It is a useful method for those using the OCXO, who find accessing R5 to be difficult. Monitor the current consumption of the U3S in “idle” mode and adjust R5 until you just about see a slight increase. This will be a fairly reasonable bias point for good operation of the PA, when you plug in the Si5351A module.



Re: QCX-Mini Display Issue

Ernie Bailey - N2DGQ
 

Ron,
Good afternoon.   I have verified the problem is on the main board. I was able to swap out the new display and new microcontroller to my working 40M rig.  The display worked, and the microcontroller indicated to Select Band as per the first alignment procedure.  I then checked continuity of pins on IC2 socket and the 2x5 male and female connector pins.  All checked out good.  

Next, I wanted to check for continuity per your suggestion from IC2 to the display according to the schematic diagram.  Upon that review I became a bit confused as what I thought was a direct connection but was not. All connections go to the blue line on the schematic.  Unfortunately, my troubleshooting skills are lacking so I'm not sure what that blue line represents.  I need a little more guidance.  While looking at the schematic for IC2 pin connectivity, do I assume for example pin #2 says "LCD D4" assume that pins goes to Display pin #4?  And pin #3 says "LCD D5", assuming connects to Display pin #5?  So on and so forth for all IC2 pins with designations of LCD.   Also Display pinout on the schematic except for VCC, GND and 12VDC, dose not make sense to me.  

Thanks in advance for your guidance.  


Re: Adjust Q1 bias on U3S - Having difficulty #bias #u3s

Nick Garrod
 

The 0.2W that you are seeing in the reports is coded in your transmission and has absolutely no relation to your actual output power, but is dependent on what figure you entered when setting it up. 


Hans details two methods of setting the bias in the instructions, this is his preferred method. 


An alternative adjustment procedure also works very nicely. I recommend this method, if you have access to a means to measure the current consumption of the kit with reasonable accuracy. You should measure the overall current consumption of the U3S kit in “idle” mode (key up, not transmitting). You do not even need to plug in the Si5351A module for this. It is a useful method for those using the OCXO, who find accessing R5 to be difficult. Monitor the current consumption of the U3S in “idle” mode and adjust R5 until you just about see a slight increase. This will be a fairly reasonable bias point for good operation of the PA, when you plug in the Si5351A module.


Re: Measurement value for QRP Dummy Load - Peak or PEP? #alignment #dummyload #test

Kees T
 

AQRP is looking into a Square Wave "Power Calibration Generator" which outputs a square wave at 100mW and 10uW into a 50 ohm load. Should be really useful for WSPR aficionados. Very simple design (Oscillator, BS170, and a couple of regulators) powered by a 9V battery.

73 Kees K5BCQ


Re: Measurement value for QRP Dummy Load - Peak or PEP? #alignment #dummyload #test

aa0jr Jakob
 

The DC voltage reading on the sense output of the dummy load is about 0.6 Volt too low because of the forward offset of the silicon diode used. Add 0.6 Volt to the reading first then do the Vpeak-to-power conversion. (Vpeak ^2 / 100).  Your QCX+ delivers about 3.4 Watts.


Adjust Q1 bias on U3S - Having difficulty #bias #u3s

Marty King
 

I have my U3S working now on 20M and I am getting a few spots. 
The reports say 0.2w. When trying to adjust R1 for the bias, I cannot see a difference in the power supply current.
And when transmitting, I cannot see a difference in the power output, either.
The current changes a lot with the LED blinking.
Anybody have other suggestions or hints?
Thanks
Marty
N7MKA


Re: How does QDX implement the raised cosine ramp in the FT8 spec? #qdx

Hans Summers
 

Hello Paul 

Yes. Constant amplitude. But my understanding of section 5, on pages 9 and 10, is that this is achieved by applying a Gaussian shape to the individual rectangular pulse making up symbol. The transmitted signal is the summation of these pulses. At the transition between symbols (audio tones) there is a summation of the preceding and succeeding tone, which are Gaussian shaped such that the summed amplitude is in fact constant.

So each symbol (tone) is a shaped pulse; but adding adjacent Gaussian smoothed pulses gives in effect a constant amplitude. It is also equivalent to a gradual frequency slide between the two tones. So there is no conflict with the "single tone FSK" theory, which is why we don't need a linear modulator and amplifier. 

And then on top of that, a raised cosine at start and end. 

That was my understanding but it's quite possible I misunderstood. 

Either way - QDX doesn't implement shaping at the start and end, but it does track the frequency slides so it minimizes trnamsitted bandwidth during the transmission itself. 

73 Hans G0UPL
http://qrp-labs.com
https://www.buymeacoffee.com/g0upl


-------- Original message --------
From: Paul Christensen <w9ac@...>
Date: Sun, Mar 27, 2022, 6:37 PM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] How does QDX implement the raised cosine ramp in the FT8 spec? #qdx

In FT8 Software.  From Joe Taylor’s QEX article:

 

“FT4 and FT8 waveforms have constant amplitude except at the very beginning and end of a transmission. FT8 signals are ramped up

gradually over a transition interval T/8, or 20 ms, at the beginning of the first sync symbol. The ramp function is a raised cosine.”

 

https://physics.princeton.edu/pulsar/k1jt/FT4_FT8_QEX.pdf

 

Paul, W9AC

 

From: QRPLabs@groups.io <QRPLabs@groups.io> On Behalf Of TomCircuit
Sent: Sunday, March 27, 2022 11:27 AM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] How does QDX implement the raised cosine ramp in the FT8 spec? #qdx

 

This is an interesting discussion to me. I work as an application engineer for a semiconductor company and define/support UHF ISM band mW output wireless sensor ICs. Most applications use FSK or GFSK to send short (~10ms duration) telegrams every minute or so. Smoothing the carrier envelope on/off edges wasn’t a concern as it wasn’t required to obtain government approval in these bands of operation. What also helped was that the antenna matching Q was reasonably high enough to prevent excessive splatter. Several years ago, S Korea added a challenging Occupied Bandwidth requirement to their RF regulations, and we had to redesign the IC to include circuitry to control the carrier envelope transitions. It added a surprising amount of complexity to the modulator, pre-driver, and driver stages to accomplish. In the QDX I suspect it would be even more challenging to implement because it is given no ‘warning’ as to when the carrier will need to be ramped up or down. 

If only the PC-side software would have the good sense to pass the frequency and amplitude information numerically via USB… :-)

-tom
NR8P


Re: My new QCX+ Desk Stand

Keith "Al" AG5GW
 

You could probably sell those on eBay....

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