Date   

Re: Video on QCX-mini test jig

W5EGA@...
 

Hans,

Bravo! That was a very clever design and a well thought out process to thoroughly test each board. I also enjoy watching your videos and listening to your explanation of how and why you design your products. It is a pleasure to see your work and I always walk away with a better understanding of your products and methods. Keep up the great work my friend! 

73 John W5EGA


Re: Failing Si5351 chip #40m #qcx+ #si5351a #40m

 

Rudd

You can replace the chip yourself.  

There are several posts on this group and excellent videos on YouTube  on how to remove and replace SMT parts.  
All you really need is a really good pair of small cutters, some solder braid and of course,  patience.  

By a spare Si5351.  You might find this chip hard to find in stock due to the global IC shortage.

If you are nervous about ‘learning’  SMT repair  on your QCX+,  you can order a SMT practice kit - they are about $5.00


--
73, Bernie, VE3FWF
(most typos in this message have been generated by highly sophisticated auto-correction software)


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

kacymcginnis@...
 

Alan,
Ok, I found a few more things.

I'm not sure if being "in circuit" will change the resistance (I'm a noob, I know) but when the board has been off for a while (cold) the resistance across R46 shows 7.5-8k ohms.

When I power up the board for a while to warm everything up then power it off, the resistance across R46 shows around 3k Ohms then slowly creeps back up to the 7.5k range. R46 fried??

Also, while power is on I tried measuring the resistance across R46 and it showed 0 ohms. Can you measure resistance across a live resistor?

I checked and re-soldered ic2 pin 26 just to be sure but no change.


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

kacymcginnis@...
 

Ronald,
I just double checked and the female header pin 6 (buttons) and IC2 pin 26 have 0 ohm continuity.
Good idea though, didn't think to check that.


Re: QCX mini unstable I-Q bal #alignment #qcxmini

howard winwood G4GPF
 

ok!, but if you are getting different readings when you press on the pot, it sounds like there is  a poor connection there or somewhere on the board when it flexes.

On 5 Mar 2021, at 19:23, M0JLA <radio@...> wrote:

Thanks for the suggestion, Howard - the boards are not in the case and the screen is separated for testing using an extension cable.  The control board is visibly clear except at the connector.
All is loosely set out on my work tray.


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

Alan G4ZFQ
 

During the fault I measured 5.02v across both R44 and R45. So not the switch then?
What about R46? If it is badly soldered or broken this could be the problem. Or the joint at pin 26 of IC2.

73 Alan G4ZFQ


Failing Si5351 chip #40m #qcx+ #si5351a #40m

ruud@...
 

I just bought and assembled a qcx+ kit. I had the problem that the bpf filter did not peak. I did not get a nice square block signal from the Si5351. Then I got a "Si5351 error" message on the screen which eventually lead to a complete short circuit and a blank screen. I used a variable power supply to apply a low voltage and ca 500 mA  and detect which component became hot, I first thought that diode D2 had failed. It appeared however that it was the Si5251 chip. Detaching the D2 gave back the normal screen, with of course still the Si5351 error message. I cannot repair this smd chip. Any suggestions?  I am thinking about using a Banggood break out board to replace the defective chip. Thanks, Ruud Lustig  the Netherlands


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

kacymcginnis@...
 

Mont, 
You may have a point there. It very well could be heat related.

The first power up today I timed and malfunctions started at 58 seconds after power up. After power cycling with no cool down time it goes straight into freakout mode. If the QCX sits for a bit before applying power again it takes between 0 and 30s to start malfunctioning.

I'll look and see if I can find some canned air. Very good idea.

Unfortunately I don't have another ATMega328 laying around to try.


Re: QCX mini unstable I-Q bal #alignment #qcxmini

M0JLA
 

Thanks for the suggestion, Howard - the boards are not in the case and the screen is separated for testing using an extension cable.  The control board is visibly clear except at the connector.
All is loosely set out on my work tray.


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

Ronald Taylor
 

Don't know if you've done so already, but you might check for continuity between IC2 pin 26 and the "buttons" pin on the female header that connects to the controls board. I found one with an open trace. Yours might have an intermittent high resistance version of an open trace. Easy to add a jumper if that's the case ... Good luck .. Ron


On Fri, Mar 5, 2021 at 11:55 AM <kacymcginnis@...> wrote:
Alan,
You are 100% correct but this is where I got 3v from-
"In all three cases, the voltage when a button is pressed, is higher than the 3V logic “1” threshold of the microcontroller." (top of page 101 QCX Mini Manual)
After re-reading the paragraph I understand it should be 0v... just like the large bold chart right above it says it should be hahaha

You are correct, all is clean and free of splashes. I've looked over the whole thing probably 20 times with a jewelers loupe and can't seem to find anything.

During the fault I measured 5.02v across both R44 and R45. So not the switch then?


Re: Ultimate3S WSPR settings

tony.volpe.1951@...
 

This table of frequencies from one of Hans's documents may help you select a correct frequency to set up your U3s depending on the band.

Therefore, ensure that for WPSR transmissions, you choose a frequency in one of the WSPR subbands according to the following table:
80m: 3.570000 – 3.570200
60m: 5.288600 – 5.288800
40m: 7.040000 – 7.040200
30m: 10.140100 – 10.140300
20m: 14.097000 – 14.097200
17m: 18.106000 – 18.106200
15m: 21.096000 – 21.096200
12m: 24.926000 – 24.926200
10m: 28.126000 – 28.126200

Set up your transmit frequency in the middle of the range to start with. Eg 7.040100 if it is on 40 meters.


Re: Ultimate3S WSPR settings

tony.volpe.1951@...
 

I assume you have set the beacon frequency correctly. Put it somewhere in the middle of the 200 hz band for starters.

Once satisfied that there is rf output, the only other issues are that the beacon is not on frequency (and it is a very narrow window you need to hit) or it is not transmitting on time.

I run a gps disciplined U3 beacon on wspr and I have a qcx and a qcx+ which run on wspr at different times. The two qcx family transceivers are ALWAYs off frequency if they have been left switched off for any amount of time and have cooled down. It took me about a while to manually manipulate my qcx+ back into the transmit window this morning. Having cooled right down it was about 200 hz off. Once there it was getting 90 hits per cycle. Before that - nothing.


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

kacymcginnis@...
 

Alan,
You are 100% correct but this is where I got 3v from-
"In all three cases, the voltage when a button is pressed, is higher than the 3V logic “1” threshold of the microcontroller." (top of page 101 QCX Mini Manual)
After re-reading the paragraph I understand it should be 0v... just like the large bold chart right above it says it should be hahaha

You are correct, all is clean and free of splashes. I've looked over the whole thing probably 20 times with a jewelers loupe and can't seem to find anything.

During the fault I measured 5.02v across both R44 and R45. So not the switch then?


Re: QXC Mini Freezing up/Phantom Presses (2021 REV 2 Board)

kacymcginnis@...
 

Ian, 
No I didn't reprogram anything. All stock.


Re: QCX mini unstable I-Q bal #alignment #qcxmini

howard winwood G4GPF
 

looks like something may be touching when you press, take the boards out of the case, plug together and check that nothing is touching, especially the tabs on the LCD.

On 5 Mar 2021, at 17:22, M0JLA <radio@...> wrote:

When I started to align my 10m QCX mini I noticed that the  readings for I-Q bal (menu 8.8) appeared to be unstable.  Several days on and numerous re-solderings and measurements I am no further forward. apart from observing that downward pressure on any of the potentiometers causes the reading to change - sometimes by a lot.  Defective joint somewhere?  I have inspected, prodded (insulated tool!) and brushed and all to no avail.   It is running now and in the past hour the index value has changed from 07 to 10 without any  action by me.  When I last tried them the Lo and Hi settings were even more unstable.  Any suggestions, please.  Rod


QCX mini unstable I-Q bal #alignment #qcxmini

M0JLA
 

When I started to align my 10m QCX mini I noticed that the  readings for I-Q bal (menu 8.8) appeared to be unstable.  Several days on and numerous re-solderings and measurements I am no further forward. apart from observing that downward pressure on any of the potentiometers causes the reading to change - sometimes by a lot.  Defective joint somewhere?  I have inspected, prodded (insulated tool!) and brushed and all to no avail.   It is running now and in the past hour the index value has changed from 07 to 10 without any  action by me.  When I last tried them the Lo and Hi settings were even more unstable.  Any suggestions, please.  Rod


Re: Ultimate3S WSPR settings

Alan G4ZFQ
 

I presume the timings and frequency calibration is ok as you say.
George,

Have you altered the Calibration parameters as it says in the manual?
Default takes a looong time.

73 Alan G4ZFQ


Re: Ultimate3S WSPR settings

George@...
 

Hi,

Thanks for that, I changed the frame start to “10 12” as you suggested. I have also listened to the output (using 20M band BTW) on the main rig, and compared it with the SOTA Beams device. They sound identical (I know that’s not particularly helpful!) but it proves the Ultimate3S is indeed transmitting, and outputting a good 300mw (ish) as power meter lowest setting is 10W.

 

But it still appears not to be received. GPS board works fine, and has picked up the locator etc from it etc, so I presume the timings and frequency calibration is ok as you say.

Somewhat stumped now – have put the SOTA beams device back, and spots are coming in fine, so it’s not the antenna.

 

Regards

George

 

From: QRPLabs@groups.io <QRPLabs@groups.io> On Behalf Of geoff M0ORE via groups.io
Sent: 04 March 2021 18:33
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] Ultimate3S WSPR settings

 

The "message" field is not used on my U3S. The callsign is entered in the field "Call".

If you are sure that RF is being transmitted, then the most likely reason for no spots is the {Frame Start} settings being not correct. Mine is set to "10 12" and works OK. Both these settings have to be even numbers. If the GPS is connected, then clock time and frequency will be OK. The "locator" field is set by the incoming data from the GPS so if you see that OK, that shows that the GPS data is being received and de-coded OK.

Geoff

On 04/03/2021 16:20, George@... wrote:

Hi,
I have recently completed a Ultimate3S, and have it working well, and talking to the GPS module. My main interest is WSPR, and I have it transmitting in this mode, but I am not getting recieved. I bought this as have a SOTA Beams commercial 200mw WSPR transmitter, and have been using it for some time, best distance recieved (With a half sized inverted G5RV) is 12,500 KM from the Faulkland islands. However the clock oscillator drifts after a few days, and transmissions are no longer recieved.
The ultimate3S gives just over 300mw with one BS170, and I was attracted to it because of the stability from the GPS board. I am wondering what goes into the "Message" setting for WSPR, the instructions are not clear, so I just put my callsign in this field, I wonder if this might be the issue?

Regards
George
G7GQC


Re: A simple QCX AGC #mods #qcx

nz0tham@...
 

Has anyone done this on the QCX+?  If so would you mind posting a how-to?

73, Bill NZ0T


AF4K Crystals to re-open

Steve Johnston
 


ANNOUNCEMENT

Steve Johnston, WD8DAS, has purchased the AF4K Crystals business and will be returning it to service as soon as possible. 
 
AF4K Crystals has been a source for vintage and modern radio crystals for nearly two decades and Steve will continue to supply ready-to-use crystals for ham radio and electronic hobbyist projects.  
 
The new website will be   http://www.af4k-crystals.com/
 
 
73
 
Steve WD8DAS
 



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