Topics

Relationship of Calibration to BFO tuning v-5 #ubitx-help #calibration

Brad
 

All,

I've been reading this group's posting for several months along with relevant postings for this topic...but I have some remaining confusion/questions.

1) What is the right order of adjustment: calibrate then adjust BFO or vis a vera? HF Signals says calibrate first.

2) When I calibrate on a strong AM broadcast signal as suggested by HF Signals I get a different settings depending on the day. Also that setting is not always the best when calibrating on 10MHz or 15 MHz. What is the preferred calibration method?

3) What is the relationship between the calibration adjustment and the BFO adjustment? Through many trial and error attempts, I find that changing the calibration setting also changes the BFO setting. Sometimes with large effect, i. e., from 11,055,500 to 11,058,800.

4) As a heads up, for those using CEC v 1.2 with Nextion 3.5 display, the config/read will display the current setting for calibration and the last setting tuned for BFO. However, if a calibration has been performed after the last BFO adjustment, the config/read will display the old BFO adjustment. A different BFO starting point will be displayed when ending Adjust BFO via the Settings screen.

73 Brad

ajparent1/KB1GMX
 

On Mon, Jul 15, 2019 at 12:06 PM, Brad wrote:
1) What is the right order of adjustment: calibrate then adjust BFO or vis a vera? HF Signals says calibrate first.
Alwaus do what the book says, they may have slues you don't.
2) When I calibrate on a strong AM broadcast signal as suggested by HF Signals I get a different settings depending on the day. Also that setting is not always the best when calibrating on 10MHz or 15 MHz. What is the preferred calibration method?
Sound like you not zero beating or the adjustment is not being kept.

3) What is the relationship between the calibration adjustment and the BFO adjustment? Through many trial and error attempts, I find that changing the calibration setting also changes the BFO setting. Sometimes with large effect, i. e., from 11,055,500 to 11,058,800.
FIrst the Main cal must be done so that the actual frequency of the BFO is correct then you tweak that for best audio.

4) As a heads up, for those using CEC v 1.2 with Nextion 3.5 display, the config/read will display the current setting for calibration and the last setting tuned for BFO. However, if a calibration has been performed after the last BFO adjustment, the config/read will display the old BFO adjustment. A different BFO starting point will be displayed when ending Adjust BFO via the Settings screen.
With CEC and non Standard Raduino code consult the author of the code.

Allison

Evan Hand
 

The calibration function adjusts the base frequency of the Si5351, so all clocks are adjusted, including the PFO and 2nd IF frequency.  For me I have found that adjusting the BFO, to get best response, then calibrate, then go back and tweak the BFO.  This process for a version 3 or 4, or a version 5 with CEC software.

To adjust the BFO, I use an audio spectrum analyzer (Free PC based).  The way that I do it is to tune to a free frequency and then adjust the BFO for a flat response between 500 and 2500 hertz.

The stock software for a version 5 now goes into transmit mode to set calibration, so be sure you have a dummy load or tuned antenna along with a second receiver.

Check out this thread:
https://groups.io/g/BITX20/topic/29604345#64518

FWIW and YMMV
73
Evan
AC9TU