I just built a QCX version 3 PCB that I purchased from QRP Labs several years ago. Upon completion of the kit I am having volume issues. With the gain turned to max I can barely hear the tone. I noticed when doing the IQ balance that I could not get higher than 3 when the directions said turn the gain control mid way and you should tune at around 9. I could only reach 3 with max gain.
Have you heard of this problem? If so what can I do to resolve this issue.
A little more info on my QCX. I am using the newest ATmega 1.09A chip. In the build I changed R41 to 150 ohm, R42 to 1.2 Kohm and C31 to 2.2 micro farad this was to improve the keying envelope.
Any input would be greatly appreciated.
Dave
W6MRD

?My max BPF adjustment was 9

On Mar 21, 2024, at 12:02?PM, Ronald Taylor <wa7gil@...> wrote:

?

Hi Dave. What signal level did you see when you did the bandpass filter adjustment??

Ron

On Thu, Mar 21, 2024 at 11:18 David Delongchamp <adukhntr@...> wrote:

I just built a QCX version 3 PCB that I purchased from QRP Labs several years ago. Upon completion of the kit I am having volume issues. With the gain turned to max I can barely hear the tone. I noticed when doing the IQ balance that I could not get higher than 3 when the directions said turn the gain control mid way and you should tune at around 9. I could only reach 3 with max gain.
Have you heard of this problem? If so what can I do to resolve this issue.
A little more info on my QCX. I am using the newest ATmega 1.09A chip. In the build I changed R41 to 150 ohm, R42 to 1.2 Kohm and C31 to 2.2 micro farad this was to improve the keying envelope.
Any input would be greatly appreciated.
Dave
W6MRD

IC-8 pins 1,2,3,5,6, and 7 were 2.4v

IC-9 pin 1 was 4.77v, pin 2 was 4.77v, pin 3 was 4.44v, pin 5 was 2.4 v, pin 6 was 2.4v and pin 7 was 2.4v

IC-10 pin 1 was 12.58v, pin 2 was 12.58v, pin 3 was 12.58v, pin 5 was 11.16v, pin 6 was 11.34v and pin 7 was 12.58 v?

Thanks,

Dave

On Mar 21, 2024, at 1:59?PM, Ronald Taylor <wa7gil@...> wrote:

?

Ok. Then you next should check the bias voltages on the op amp ICs 8,9 and 10. With your DVM you should see about 2.5v on pins 1,2,3,5,6&7 of IC 8 and on pins 5,6&7 of IC9. You should also see about 4.8v on pins 1,2&3 of IC9 and a bit less than half the input voltage on pins 1,2,3,5,6&7 of IC10. Please verify those voltages. Thanks….Ron

On Thu, Mar 21, 2024 at 12:31 David Delongchamp <adukhntr@...> wrote:

?My max BPF adjustment was 9

On Mar 21, 2024, at 12:02?PM, Ronald Taylor <wa7gil@...> wrote:

?

Hi Dave. What signal level did you see when you did the bandpass filter adjustment??

Ron

On Thu, Mar 21, 2024 at 11:18 David Delongchamp <adukhntr@...> wrote:

I just built a QCX version 3 PCB that I purchased from QRP Labs several years ago. Upon completion of the kit I am having volume issues. With the gain turned to max I can barely hear the tone. I noticed when doing the IQ balance that I could not get higher than 3 when the directions said turn the gain control mid way and you should tune at around 9. I could only reach 3 with max gain.
Have you heard of this problem? If so what can I do to resolve this issue.
A little more info on my QCX. I am using the newest ATmega 1.09A chip. In the build I changed R41 to 150 ohm, R42 to 1.2 Kohm and C31 to 2.2 micro farad this was to improve the keying envelope.
Any input would be greatly appreciated.
Dave
W6MRD

Ron:

?I got 11.16v off of R40 and 0 volts from R39 and I’m getting 11.6v on pin 5 of IC-10

I’m not sure what you meant by the junction ?of R40 and R39. I took voltage readings from the wire off of R40 and then R39.

Thanks,

Dave

On Mar 21, 2024, at 4:21?PM, Ronald Taylor <wa7gil@...> wrote:

?

OK Dave, looks like there's something wrong in the area of R39 and R40. Those two resistors form a voltage divider from the 12v input and should show about 6 volts at the junction of the two. That same voltage should be on pin 5 of IC10 from where it then appears on the rest of the pins, 1,2,3,6&7. Please check those resistors and the voltage?between?them. If it is about 6 volts then check for continuity from the junction of the two resistors to pin 5 of IC10. Look at the schematic to see where this is going. Let us know what you find ... 73 .. Ron

On Thu, Mar 21, 2024 at 3:23?PM David Delongchamp <adukhntr@...> wrote:

IC-8 pins 1,2,3,5,6, and 7 were 2.4v

IC-9 pin 1 was 4.77v, pin 2 was 4.77v, pin 3 was 4.44v, pin 5 was 2.4 v, pin 6 was 2.4v and pin 7 was 2.4v

IC-10 pin 1 was 12.58v, pin 2 was 12.58v, pin 3 was 12.58v, pin 5 was 11.16v, pin 6 was 11.34v and pin 7 was 12.58 v?

Thanks,

Dave

On Mar 21, 2024, at 1:59?PM, Ronald Taylor <wa7gil@...> wrote:

?

Ok. Then you next should check the bias voltages on the op amp ICs 8,9 and 10. With your DVM you should see about 2.5v on pins 1,2,3,5,6&7 of IC 8 and on pins 5,6&7 of IC9. You should also see about 4.8v on pins 1,2&3 of IC9 and a bit less than half the input voltage on pins 1,2,3,5,6&7 of IC10. Please verify those voltages. Thanks….Ron

On Thu, Mar 21, 2024 at 12:31 David Delongchamp <adukhntr@...> wrote:

?My max BPF adjustment was 9

On Mar 21, 2024, at 12:02?PM, Ronald Taylor <wa7gil@...> wrote:

?

Hi Dave. What signal level did you see when you did the bandpass filter adjustment??

Ron

On Thu, Mar 21, 2024 at 11:18 David Delongchamp <adukhntr@...> wrote:

I just built a QCX version 3 PCB that I purchased from QRP Labs several years ago. Upon completion of the kit I am having volume issues. With the gain turned to max I can barely hear the tone. I noticed when doing the IQ balance that I could not get higher than 3 when the directions said turn the gain control mid way and you should tune at around 9. I could only reach 3 with max gain.
Have you heard of this problem? If so what can I do to resolve this issue.
A little more info on my QCX. I am using the newest ATmega 1.09A chip. In the build I changed R41 to 150 ohm, R42 to 1.2 Kohm and C31 to 2.2 micro farad this was to improve the keying envelope.
Any input would be greatly appreciated.
Dave
W6MRD

Hi Ron:

I checked the schematic and found the junction of R39 and R40. I was able to connect the 2 resistors. The voltage readings did not change. So I checked the ohm value of the two resistors and got 10K on R40 and a error reading on R39. Based on that I’m thinking R39 is faulty and I should replace it. What size resistor is R39 I know it’s 10K. In searching for one what am I looking for in its values??

Thanks,?

Dave

On Mar 21, 2024, at 6:07?PM, Ronald Taylor <wa7gil@...> wrote:

?

OK Dave, it sounds like there is no connection between R39 and R40 and there should be. One side of R39 connects to ground (0 v) and the other side is supposed to connect to R40. Where they connect together is what I called the junction of the two. This junction is supposed to connect to pin 5 of IC10. The other side of R40 is connected to 12v. Since you see about 12 v on pin 5 of IC10, then there is no continuity between R39 and R4o. Please look at the circuit diagram and the board layout drawings and determine where that interconnection is supposed to be and solder a short jumper?wire between the two points to restore the missing connection?between the two resistors. Good luck .. 73 .. Ron

On Thu, Mar 21, 2024 at 5:01?PM David Delongchamp <adukhntr@...> wrote:

Ron:

?I got 11.16v off of R40 and 0 volts from R39 and I’m getting 11.6v on pin 5 of IC-10

I’m not sure what you meant by the junction ?of R40 and R39. I took voltage readings from the wire off of R40 and then R39.

Thanks,

Dave

On Mar 21, 2024, at 4:21?PM, Ronald Taylor <wa7gil@...> wrote:

?

OK Dave, looks like there's something wrong in the area of R39 and R40. Those two resistors form a voltage divider from the 12v input and should show about 6 volts at the junction of the two. That same voltage should be on pin 5 of IC10 from where it then appears on the rest of the pins, 1,2,3,6&7. Please check those resistors and the voltage?between?them. If it is about 6 volts then check for continuity from the junction of the two resistors to pin 5 of IC10. Look at the schematic to see where this is going. Let us know what you find ... 73 .. Ron

On Thu, Mar 21, 2024 at 3:23?PM David Delongchamp <adukhntr@...> wrote:

IC-8 pins 1,2,3,5,6, and 7 were 2.4v

IC-9 pin 1 was 4.77v, pin 2 was 4.77v, pin 3 was 4.44v, pin 5 was 2.4 v, pin 6 was 2.4v and pin 7 was 2.4v

IC-10 pin 1 was 12.58v, pin 2 was 12.58v, pin 3 was 12.58v, pin 5 was 11.16v, pin 6 was 11.34v and pin 7 was 12.58 v?

Thanks,

Dave

On Mar 21, 2024, at 1:59?PM, Ronald Taylor <wa7gil@...> wrote:

?

Ok. Then you next should check the bias voltages on the op amp ICs 8,9 and 10. With your DVM you should see about 2.5v on pins 1,2,3,5,6&7 of IC 8 and on pins 5,6&7 of IC9. You should also see about 4.8v on pins 1,2&3 of IC9 and a bit less than half the input voltage on pins 1,2,3,5,6&7 of IC10. Please verify those voltages. Thanks….Ron

On Thu, Mar 21, 2024 at 12:31 David Delongchamp <adukhntr@...> wrote:

?My max BPF adjustment was 9

On Mar 21, 2024, at 12:02?PM, Ronald Taylor <wa7gil@...> wrote:

?

Hi Dave. What signal level did you see when you did the bandpass filter adjustment??

Ron

On Thu, Mar 21, 2024 at 11:18 David Delongchamp <adukhntr@...> wrote:

I just built a QCX version 3 PCB that I purchased from QRP Labs several years ago. Upon completion of the kit I am having volume issues. With the gain turned to max I can barely hear the tone. I noticed when doing the IQ balance that I could not get higher than 3 when the directions said turn the gain control mid way and you should tune at around 9. I could only reach 3 with max gain.
Have you heard of this problem? If so what can I do to resolve this issue.
A little more info on my QCX. I am using the newest ATmega 1.09A chip. In the build I changed R41 to 150 ohm, R42 to 1.2 Kohm and C31 to 2.2 micro farad this was to improve the keying envelope.
Any input would be greatly appreciated.
Dave
W6MRD

Any size that fits is fine. I think those are 1/4 watt. Sounds like you found the problem. Good luck. …. Ron

On Fri, Mar 22, 2024 at 10:43 David Delongchamp <adukhntr@...> wrote:

Hi Ron:

I checked the schematic and found the junction of R39 and R40. I was able to connect the 2 resistors. The voltage readings did not change. So I checked the ohm value of the two resistors and got 10K on R40 and a error reading on R39. Based on that I’m thinking R39 is faulty and I should replace it. What size resistor is R39 I know it’s 10K. In searching for one what am I looking for in its values??

Thanks,?

Dave

On Mar 21, 2024, at 6:07?PM, Ronald Taylor <wa7gil@...> wrote:

?

OK Dave, it sounds like there is no connection between R39 and R40 and there should be. One side of R39 connects to ground (0 v) and the other side is supposed to connect to R40. Where they connect together is what I called the junction of the two. This junction is supposed to connect to pin 5 of IC10. The other side of R40 is connected to 12v. Since you see about 12 v on pin 5 of IC10, then there is no continuity between R39 and R4o. Please look at the circuit diagram and the board layout drawings and determine where that interconnection is supposed to be and solder a short jumper?wire between the two points to restore the missing connection?between the two resistors. Good luck .. 73 .. Ron

On Thu, Mar 21, 2024 at 5:01?PM David Delongchamp <adukhntr@...> wrote:

Ron:

?I got 11.16v off of R40 and 0 volts from R39 and I’m getting 11.6v on pin 5 of IC-10

I’m not sure what you meant by the junction ?of R40 and R39. I took voltage readings from the wire off of R40 and then R39.

Thanks,

Dave

On Mar 21, 2024, at 4:21?PM, Ronald Taylor <wa7gil@...> wrote:

?

OK Dave, looks like there's something wrong in the area of R39 and R40. Those two resistors form a voltage divider from the 12v input and should show about 6 volts at the junction of the two. That same voltage should be on pin 5 of IC10 from where it then appears on the rest of the pins, 1,2,3,6&7. Please check those resistors and the voltage?between?them. If it is about 6 volts then check for continuity from the junction of the two resistors to pin 5 of IC10. Look at the schematic to see where this is going. Let us know what you find ... 73 .. Ron

On Thu, Mar 21, 2024 at 3:23?PM David Delongchamp <adukhntr@...> wrote:

IC-8 pins 1,2,3,5,6, and 7 were 2.4v

IC-9 pin 1 was 4.77v, pin 2 was 4.77v, pin 3 was 4.44v, pin 5 was 2.4 v, pin 6 was 2.4v and pin 7 was 2.4v

IC-10 pin 1 was 12.58v, pin 2 was 12.58v, pin 3 was 12.58v, pin 5 was 11.16v, pin 6 was 11.34v and pin 7 was 12.58 v?

Thanks,

Dave

On Mar 21, 2024, at 1:59?PM, Ronald Taylor <wa7gil@...> wrote:

?

Ok. Then you next should check the bias voltages on the op amp ICs 8,9 and 10. With your DVM you should see about 2.5v on pins 1,2,3,5,6&7 of IC 8 and on pins 5,6&7 of IC9. You should also see about 4.8v on pins 1,2&3 of IC9 and a bit less than half the input voltage on pins 1,2,3,5,6&7 of IC10. Please verify those voltages. Thanks….Ron

On Thu, Mar 21, 2024 at 12:31 David Delongchamp <adukhntr@...> wrote:

?My max BPF adjustment was 9

On Mar 21, 2024, at 12:02?PM, Ronald Taylor <wa7gil@...> wrote:

?

Hi Dave. What signal level did you see when you did the bandpass filter adjustment??

Ron

On Thu, Mar 21, 2024 at 11:18 David Delongchamp <adukhntr@...> wrote:

I just built a QCX version 3 PCB that I purchased from QRP Labs several years ago. Upon completion of the kit I am having volume issues. With the gain turned to max I can barely hear the tone. I noticed when doing the IQ balance that I could not get higher than 3 when the directions said turn the gain control mid way and you should tune at around 9. I could only reach 3 with max gain.
Have you heard of this problem? If so what can I do to resolve this issue.
A little more info on my QCX. I am using the newest ATmega 1.09A chip. In the build I changed R41 to 150 ohm, R42 to 1.2 Kohm and C31 to 2.2 micro farad this was to improve the keying envelope.
Any input would be greatly appreciated.
Dave
W6MRD

Ron:

I checked pin 4 on IC 10 and had 12v. I connected a ground wire to pin 4 and now I get 6v on pins 1, 2, 3, 5, 6, and 7. I am getting 13v on pin 8?

Is that correct readings?

Thanks,

Dave

On Apr 1, 2024, at 1:31?PM, Ronald Taylor <wa7gil@...> wrote:

?If you see 12v on pin 4 of that chip then it sounds like it is not grounded. Pin 4 is supposed to go to ground. Use your DVM to see if it is grounded. If not, reheat the connection to pin 4. If the connection itself doesn't appear to go to ground, then run a short jumper from pin 4 to the nearest ground point. Good luck ... Ron