Date   
QCX-40 "too loud"

Stephan Paukner
 

Hi all,

I finished the QCX-40 a few days ago, and it seems to work so far: I could successfully tune to maximum BPF, I measure 4.3 W output at 12 V input with the built-in meter, I can hear other stations when I plug it to an antenna, and the decoder works for TX and RX. So far, so good! (I haven't QSO yet, as I'm a CW beginner, but time is ripe.)

But: I can operate it only with gain close to zero, at eight o'clock position or so. At 9 o'clock, it's already very loud, and at 10 or 11, a loud feedback tone comes up. I couldn't go through the I-Q and Phase tuning procedure correctly: It's quickly at a reading of 12. I assume I killed Q7, the BS170 MOSFET below the gain control: It had too long pins which touched the gain control at its rightmost contact (from the top view). I unsoldered the gain control and shortened Q7's pins, but that didn't change this behavior.

Has anybody got an idea how I could trace this down? What voltages could I check to see where the fault is? I don't own an oscilloscope, though. I looked at the troubleshooting guide, but I didn't find reference voltages for Q7.
mni tks!

73 de Stephan, OE3SPR

Re: Resistor Error ?

Bruce K1FFX
 

Hi, Paul -

Based on advice from the Elecraft forum's long-time guru (W3FPR), I've settled on snipping out the old component, then easily pulling out the leftover leads on each end with long-nose pliers, and then using a toothpick to clean out the through holes.  I've had no issues with messing up the holes, lifting the soldering pads, etc., since moving to this method.  Haven't used the solder sucker in some time now.

Had numerous chances to do this while blowing out the BS170 transistors on my U3S ... no problems with removing the failed parts or with installing new parts on the solder pads.

Best -

Bruce K1FFX

Re: Is wsprnet falling to pieces again ?

Chris Wilson
 

Hello Alan,

 Wednesday, September 18, 2019

 I have yet to enjoy a really good free lunch, such is life. One day someone will see a possibility of making a few quid out of this very popular and growing (seemingly exponentially), medium. Until such a time we need to enjoy our  less than perfect freebie  ;) I agree it can be a pain with the need for the keen to manually upload spots at a quiet time. 


Best regards,
 Chris    2E0ILY       
mailto:chris@...



It works fine in the mornings as do the 3rd party extensions in the UK. I complained about slow operation a short while back, seems something good happened. What do you want for free?
 
73
Alan
G8LCO
 
Sent from 
Mail for Windows 10
 

From: Andy Brilleaux via Groups.Io
Sent: 18 September 2019 07:02 PM
To: 
QRPLabs@groups.io
Subject: [QRPLabs] Is wsprnet falling to pieces again ?
 
Really dreadful in the last few months.
Long response times and failed connections.
At one point this would be a xmas holidays event (peak time).
Now is any time.

73 de Andy 
 

--
Best regards, Chris Wilson (2E0ILY)

Re: Resistor Error ?

Charles W. Powell
 

Yes, that way the solder flows into the wick as soon as it heats.  Personally I almost always use the solder sucker.  If you didn’t bend the lead when installing, often the component will just fall out of the spot.  You can also use a toothpick to apply light pressure to coax it out.

73,

Charles - NK8O

On Sep 18, 2019, at 4:07 PM, w2eck <eckerpw@...> wrote:

Alan & Charles- tnx for quick reply. Understand- got to be corrected. I have solder wick & a large solder sucker, but my expertise in using both is less then polished. Will give it a go and hopefully can salvage R18. 
--- So Charles - when you say use copious flux, do you put the flux on the wick?? That would be new trick for me.

Tnx agn
Paul
w2eck 

Re: Resistor Error ?

w2eck
 

Alan & Charles- tnx for quick reply. Understand- got to be corrected. I have solder wick & a large solder sucker, but my expertise in using both is less then polished. Will give it a go and hopefully can salvage R18. 
--- So Charles - when you say use copious flux, do you put the flux on the wick?? That would be new trick for me.

Tnx agn
Paul
w2eck 

Re: Resistor Error ?

SkipF, NT1G <skip.flem@...>
 

I suggest you carefully remove the installed resistor and put it
in the proper location...at first.
Gud Luck!
De NT1G

On Wed, Sep 18, 2019, 4:36 PM w2eck <eckerpw@...> wrote:

Building the QCX and when I got down to installing last two resistors and think I found an error.

I have R18 (4.3k) installed in R41's location and R41 (470ohm) – not yet installed.

So my question, albeit possibly a dumb one, do I need to uninstall R18 and procure another to install or will the QCX work with these two resistors transposed?

73 Paul w2eck

Re: Resistor Error ?

Charles W. Powell
 

They need to go in the correct places but you may be able to remove the resistor without damaging it. Do you have a solder sucker tool or wick?  I have removed many components to move them (guess why that would be?) and I can do it with about 99% success without any damage to the board or the component.  The trick with solder wick is to use copious flux to get the solder to flow out into the wick.  I have a solder sucker that can make the holes nearly clean on the first try.

73,

Charles - NK8O

On Sep 18, 2019, at 3:36 PM, w2eck <eckerpw@...> wrote:

Building the QCX and when I got down to installing last two resistors and think I found an error.
I have R18 (4.3k) installed in R41's location and R41 (470ohm) – not yet installed.
So my question, albeit possibly a dumb one, do I need to uninstall R18 and procure another to install or will the QCX work with these two resistors transposed?
73 Paul w2eck

Re: Resistor Error ?

Alan G4ZFQ
 

I have R18 (4.3k) installed in R41's location and R41 (470ohm) – not yet installed.
Paul

R18 must be 4.3K, IQ balance will be affected by the change in gain.
R41 might work with a 4.3K but it is no doubt specified as 470 for a reason.
Best do it right.

73 Alan G4ZFQ

Resistor Error ?

w2eck
 

Building the QCX and when I got down to installing last two resistors and think I found an error.

I have R18 (4.3k) installed in R41's location and R41 (470ohm) – not yet installed.

So my question, albeit possibly a dumb one, do I need to uninstall R18 and procure another to install or will the QCX work with these two resistors transposed?

73 Paul w2eck

Re: Is wsprnet falling to pieces again ?

Graham, VE3GTC
 

Indeed.  Some times of the day it is relatively quite quick and responsive and at other times very slow or times out.

Day time seems to be better than mid to late evening (local North America Eastern Time) - perhaps similar in other areas?

Sometimes it seems if try to connect or refresh a connection at an odd minute  i.e. 01, 03, 05, 07, 09, 11 ... etc the connection seems to be better than when done much closer to even minute. We know that WSJT-x and other programs do their upload after the last WSPR frame which ends just before the even minute.  Too bad the application does not permit selection of an "off" upload time or better has the inbuilt smarts to upload at some random time based on location or some such thing.  Can you just imagine the network load of 10,000 (more or less) WSJT-X applications trying to upload to the server, what a traffic jam that would be!

Google maps are something else again - Open Source Maps would be a better choice and there was some talk changing but doesn't appear to be any movement.

cheers, Graham ve3gtc

Re: Is wsprnet falling to pieces again ?

Roger Hill
 

I disagree. It is pretty bad here near Leeds most times of the day.
Roger
G3YTN


On 18 September 2019 19:18:59 BST, "geoff M0ORE via Groups.Io" <m0ore@...> wrote:

No problem in England at any time of day, Google map not registered is a distraction but does not stop function.

On 18/09/2019 19:06, Alan wrote:

It works fine in the mornings as do the 3rd party extensions in the UK. I complained about slow operation a short while back, seems something good happened. What do you want for free?

 

73

Alan

G8LCO

 

Sent from Mail for Windows 10

 

From: Andy Brilleaux via Groups.Io
Sent: 18 September 2019 07:02 PM
To: QRPLabs@groups.io
Subject: [QRPLabs] Is wsprnet falling to pieces again ?

 

Really dreadful in the last few months.
Long response times and failed connections.
At one point this would be a xmas holidays event (peak time).
Now is any time.

73 de Andy

 


--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Re: Is wsprnet falling to pieces again ?

geoff M0ORE
 

No problem in England at any time of day, Google map not registered is a distraction but does not stop function.

On 18/09/2019 19:06, Alan wrote:

It works fine in the mornings as do the 3rd party extensions in the UK. I complained about slow operation a short while back, seems something good happened. What do you want for free?

 

73

Alan

G8LCO

 

Sent from Mail for Windows 10

 

From: Andy Brilleaux via Groups.Io
Sent: 18 September 2019 07:02 PM
To: QRPLabs@groups.io
Subject: [QRPLabs] Is wsprnet falling to pieces again ?

 

Really dreadful in the last few months.
Long response times and failed connections.
At one point this would be a xmas holidays event (peak time).
Now is any time.

73 de Andy

 

Re: Is wsprnet falling to pieces again ?

Alan
 

It works fine in the mornings as do the 3rd party extensions in the UK. I complained about slow operation a short while back, seems something good happened. What do you want for free?

 

73

Alan

G8LCO

 

Sent from Mail for Windows 10

 

From: Andy Brilleaux via Groups.Io
Sent: 18 September 2019 07:02 PM
To: QRPLabs@groups.io
Subject: [QRPLabs] Is wsprnet falling to pieces again ?

 

Really dreadful in the last few months.
Long response times and failed connections.
At one point this would be a xmas holidays event (peak time).
Now is any time.

73 de Andy

 

Is wsprnet falling to pieces again ?

Andy Brilleaux <punkbiscuit@...>
 

Really dreadful in the last few months.
Long response times and failed connections.
At one point this would be a xmas holidays event (peak time).
Now is any time.

73 de Andy

Re: AGC

Axel
 

Hi Allison,
Thank you for your advice! I think, this will be very helpful. I'm curious about what the result will be.

73 Axel DF1ET

Re: AGC

ajparent1/KB1GMX
 

The problem with AGC on any radio is keeping TX operations from
pumping up the RX agc since most derieve AGC control voltage
from RX audio.

Two things;
Minimize the side tone level.  As tx sidetone will also drive audio agc.

Insure any rx to tx transfer does nto cause pops or clicks as that
also show up int he audio and will drive most audio agc to become
active (or over active).

Clamp the AGC to some level that represents a no signal receive
during transmit.  That allows the AGC to only work on receive.

If those things are properly done then agc on RX will not harm
the QSK capability.  Didn't say it was easy.

Allison

Re: AGC

Axel
 

My experiences with QSK with AGC now are (speed: 15 wpm): Between words, AGC's decay and receiver's sensitivity is enough to here the received signal. Between letters, I had once the impression to hear a received signal, but would say, generally sensitivity is to low between letters.

I intend to either increase AGC speed or to change the way sidetone is fed into the audio stage.

73
Axel, DF1ET

Re: Si5351A error

geoff M0ORE
 

It's that little gremlin that the solder manufacturers put in the solder to make disappear when you turn away.

On 17/09/2019 22:44, Charles Mims wrote:
Thanks for the help.  One of the leads on D1 had become unsoldered.
Now to get everything else going.

73 Charles KG5ZLH

On Mon, Sep 16, 2019 at 2:44 AM Alan G4ZFQ <alan4alan@...> wrote:
> When restarted i get
> the message Si5351A error.  Have I fried it?  If not how do I get past
> the error message.

Charles,

This means that IC2 is not talking to IC1.
Check the SCL, SDA connections. And the voltage on those lines. Also the
voltage supplied by D1/2. Check Xtal 2 is soldered well.
Look at the Si5351 with a glass, in the past a few have been badly soldered.

73 Alan G4ZFQ



Re: Si5351A error

Charles Mims
 

Thanks for the help.  One of the leads on D1 had become unsoldered.
Now to get everything else going.

73 Charles KG5ZLH


On Mon, Sep 16, 2019 at 2:44 AM Alan G4ZFQ <alan4alan@...> wrote:
> When restarted i get
> the message Si5351A error.  Have I fried it?  If not how do I get past
> the error message.

Charles,

This means that IC2 is not talking to IC1.
Check the SCL, SDA connections. And the voltage on those lines. Also the
voltage supplied by D1/2. Check Xtal 2 is soldered well.
Look at the Si5351 with a glass, in the past a few have been badly soldered.

73 Alan G4ZFQ



Re: calibration of U3S + GPS #u3s #qlg1 #si5351a

f5ihn
 

Hi,

problem solved !

I was confused by the presence of 1 pps of the yellow led, which in turn is the TX data being sent.
The green led of the real 1 pps signal is off, I checked and the RF module doesn't send any signal.
No short-ciircuit, nor any trouble with the 74ACT08 that I removed for testing.

I replaced the board by another one I purchased earlier for the QCX, and all is fine now.

I'll check with Hans if there's a chance to get an RF module for replacement.

73
F5IHN David