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New V6 CW tone frequency

rskarka@...
 

Yesterday I received my new uBITX v6 full kit and assembled it. After a short function check (could hear some CW and FT8 signals), I installed CEC firmware and Nextion display. Everything worked right out of the box, but later I noticed, that when I tune to CW signals, the audio tone is very high. When I tune the HF for strongest audio signal, the audio tone is around 5khz, and when I change the frequency to get the tone lower, the signal disappears before getting down to the range of 1kHz.
For testing, I tuned to a strong CW station in LSB, USB, CWL and CWU. The highest volume for each mode was approximately:

7029 kHz LSB
7033 kHz CWL
7023 kHz CWU
7025 kHz USB

With SSB modes I can tune the tone frequency down, but also the signal is stronger at higher frequencies than 800Hz.


So far, I didn't do any calibration, and right after uploading the CEC firmware, I downloaded the eeprom data with the ubitx manager software.
Could this be a frequency or bfo calibration issue? Im not sure, because it is mostly a problem in CW modes, and I thought the boards come calibrated from the factory.

Should I go back to the stock fw and display to run the calibration procedure of the V6 firmware with the web spectrum analyzer tool?

Something else to check? I have an HP/Agilent Oscilloscope, but the last calibration of that was 2003, so not sure how accurate the frequency counter of that is.

Thanks for help,

Robert

Dale Parfitt
 

It certainly sounds as though you need to calibrate  the BFO.  As is signals, are on the edge of the crystal filter.

When mine arrived sidebands were reversed. Calibrating the BFO fixed it instantly.

 

Dale W4OP

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of rskarka@...
Sent: Thursday, May 28, 2020 7:06 AM
To: bitx20@groups.io; robert.skarka@...
Subject: [BITX20] New V6 CW tone frequency

 

Yesterday I received my new uBITX v6 full kit and assembled it. After a short function check (could hear some CW and FT8 signals), I installed CEC firmware and Nextion display. Everything worked right out of the box, but later I noticed, that when I tune to CW signals, the audio tone is very high. When I tune the HF for strongest audio signal, the audio tone is around 5khz, and when I change the frequency to get the tone lower, the signal disappears before getting down to the range of 1kHz.

For testing, I tuned to a strong CW station in LSB, USB, CWL and CWU. The highest volume for each mode was approximately:

 

7029 kHz LSB

7033 kHz CWL

7023 kHz CWU

7025 kHz USB

 

With SSB modes I can tune the tone frequency down, but also the signal is stronger at higher frequencies than 800Hz

 

 

So far, I didn't do any calibration, and right after uploading the CEC firmware, I downloaded the eeprom data with the ubitx manager software.

Could this be a frequency or bfo calibration issue? Im not sure, because it is mostly a problem in CW modes, and I thought the boards come calibrated from the factory.

 

Should I go back to the stock fw and display to run the calibration procedure of the V6 firmware with the web spectrum analyzer tool?

 

Something else to check? I have an HP/Agilent Oscilloscope, but the last calibration of that was 2003, so not sure how accurate the frequency counter of that is.

 

Thanks for help,

 

Robert

Evan Hand
 

I would recommend that all check calibration, as there have been a lot of reports of issues.  None of the 3 boards that I bought were calibrated accurately from the factory. 

Ashhar Farhan has made it fairly simple for the version 6 boards.  The video instructions are here:
https://www.youtube.com/watch?v=t6LGXhS4_O8
with the BFO tuning aid here:
https://www.hfsignals.com/index.php/bfo-tuning-aid/

The above should be done as the first step in solving sensitivity, power, transmission distortion, or selectivity issues.  The basic steps are the same for all boards, the details of how to get to the calibration and for the version 5 board the fact that stock software transmits a 10 MHz carrier for the calibration.  The BFO adjustment is the same.
73
Evan
AC9TU

roebi@...
 

Finally I found the problem.

After calibrating, the SSB reception was improved, but for CW the filter was still too high. Then I realized, that there is a 2nd bfo calibration for CW in the CEC firmware, and the value was 0. After I copied the bfo calibration to the cw bfo calibration, I was able to get the CW tone to where it should be. Finally I increased the value, to make the filter a little better for CW. 
Still the filter has less attenuation on frequencies higher than 1kHz, so probably I will add one of the CW filter mods.

Thanks, Robert