Topics

Frequency calibration V5

Morris Ford
 

I am trying to calibrate a V5 box using a frequency meter. I need someone to interpret the instructions for that in the user manual for CEC software. I tried just transmit and adjust and not the ing happens. I tried into calibrate and transmit and the adjust and nothing happens. 
Any help?

Morris
K7LSV

Morris Ford
 

I neglected to say:
This a new just built v5. It has CEC firmware v 1.20.
IT has a nextion 3.2 display.

Any help greatly appreciated.

Morris
K7LSV


On Fri, Dec 13, 2019 at 9:31 AM Morris Ford via Groups.Io <morrishford=gmail.com@groups.io> wrote:
I am trying to calibrate a V5 box using a frequency meter. I need someone to interpret the instructions for that in the user manual for CEC software. I tried just transmit and adjust and not the ing happens. I tried into calibrate and transmit and the adjust and nothing happens. 
Any help?

Morris
K7LSV

CR
 

The firmware instructions for calibration for ver 5 appear to be incorrect. I achieved calibration by many iterations of the following: Tune to 10.000 MHz on the dial. (WWV will actually probably be 1.5 kHz lower.) Go to Settings, then Calibration. (The unit will go into TX.) Rotate tuning to increase the offset number shown to say 10. Exit settings, then exit menu. Check where WWV is now. Repeat until zeroed. 

During these iterations you may have to intersperse going to Settings, Calibration, Bfo to lower the audio spectrum band to where you are able to hear WWV clearly. 
 
If you are out of range of WWV you will need a replacement 10 MHz source.

After calibration you then need to place the Bfo correctly within the filter. Unfortunately, the firmware does not quite move the calibrated frequency in parallel, so you may have fine tune calibration again.  

I would appreciate hearing about a faster method.

Chuck w8mqw


On Fri, Dec 13, 2019, 13:46 Morris Ford <morrishford@...> wrote:
I neglected to say:
This a new just built v5. It has CEC firmware v 1.20.
IT has a nextion 3.2 display.

Any help greatly appreciated.

Morris
K7LSV


On Fri, Dec 13, 2019 at 9:31 AM Morris Ford via Groups.Io <morrishford=gmail.com@groups.io> wrote:
I am trying to calibrate a V5 box using a frequency meter. I need someone to interpret the instructions for that in the user manual for CEC software. I tried just transmit and adjust and not the ing happens. I tried into calibrate and transmit and the adjust and nothing happens. 
Any help?

Morris
K7LSV

Morris Ford
 

Hey Chuck,
Sounds like your experience is quite a lot like mine. One difference is that I have a digital frequency meter. 
I use that to transmit on a known frequency and then compare it to the frequency on the meter. The biggest problem I had 
was that I never was able to get any movement of indications during calibration. I was forced to do the calibrate
 a little then check where the frequency was after that calibration

The biggest problem I had using the calibrate for a small number then check, then calibrate again and check, over and over.
That procedure did move the frequency but in a very random way. For example, it would be a couple of thousand off, like xmit 28,000,300 and meter
28,003,678 and I would move by +100 in the calibration. The result would be somewhere around the target frequency but sometimes above the target and sometimes below.
I would then calibrate again moving by -100 and it would not come back to the prior setting. Also if I did this with small shift numbers like 5 to 10 the results were very random.
Finally, I just kept calibrating over and over with random small numbers until I just happened to land on a number that was less that 30 cycles off and left it that way.
I am pretty sure that when I do the BFO calibration the frequency stuff will be off.

The largest issue is that calibration does not work like the documentation states in terms of being able to shift calibration while observing where
the calibration is. Because of this lack of function the repeated calibration method is very difficult due to the random effect of 
calibration based on the number input during calibration. My suspicion is that there is a calculation problem when trying to come up with an actual
frequency change.

By the way I was using a calibration in the 10 meter area to keep the power level down going to the frequency meter.

Maybe this stuff will help move to discussion about calibration forward a little.

Morris
K7LSV


On Fri, Dec 13, 2019 at 3:04 PM CR <maccluer13@...> wrote:
The firmware instructions for calibration for ver 5 appear to be incorrect. I achieved calibration by many iterations of the following: Tune to 10.000 MHz on the dial. (WWV will actually probably be 1.5 kHz lower.) Go to Settings, then Calibration. (The unit will go into TX.) Rotate tuning to increase the offset number shown to say 10. Exit settings, then exit menu. Check where WWV is now. Repeat until zeroed. 

During these iterations you may have to intersperse going to Settings, Calibration, Bfo to lower the audio spectrum band to where you are able to hear WWV clearly. 
 
If you are out of range of WWV you will need a replacement 10 MHz source.

After calibration you then need to place the Bfo correctly within the filter. Unfortunately, the firmware does not quite move the calibrated frequency in parallel, so you may have fine tune calibration again.  

I would appreciate hearing about a faster method.

Chuck w8mqw

On Fri, Dec 13, 2019, 13:46 Morris Ford <morrishford@...> wrote:
I neglected to say:
This a new just built v5. It has CEC firmware v 1.20.
IT has a nextion 3.2 display.

Any help greatly appreciated.

Morris
K7LSV


On Fri, Dec 13, 2019 at 9:31 AM Morris Ford via Groups.Io <morrishford=gmail.com@groups.io> wrote:
I am trying to calibrate a V5 box using a frequency meter. I need someone to interpret the instructions for that in the user manual for CEC software. I tried just transmit and adjust and not the ing happens. I tried into calibrate and transmit and the adjust and nothing happens. 
Any help?

Morris
K7LSV

Evan Hand
 

I have not used it, so cannot attest to the accuracy.

To help speed up the process you might want to read this thread and try the calibration spreadsheet.

https://groups.io/g/BITX20/message/72183?p=,,,20,0,0,0::Created,,calibration+spreadsheet,20,2,0,34330593

A take away from this that using the search function of the messages is one of the best ways to find out if someone else has already gone through the issue.  Being a relatively long time user of this site, and reading most of the messages, I can see that the same problems keep coming up.

I would suggest that a new member guide be part of the prerequisite for membership.  Part of that instruction should be the best way to find information on the sire.  This would be both helpful to the new member, and reduce the amount of rehash that seems to go on.  I can state that having to reiterate prior solutions to new members does get old after 3 or 4 times.  Calibration is one of those that keep coming up.  I had to use the search function myself to find the above thread.  It would have sped up the process for Morris if he knew about that feature in Groups.io.

Above are my thoughts, yours may be different, and that is OK
73
Evan
AC0TU

73
Evan
AC9T

Jerry Gaffke
 

Apparently, V6 firmware can be used on earlier rigs, making a minor adjustment if you have a 12mhz IF.
Searching for "set_calibration" in ubitx_setup.ino for V6, it appears
that this new code is using the algorithm of   https://groups.io/g/BITX20/message/71281
Which is most welcome.

The V6 code adjusts the si5351bx_vco in steps of 875 hz.
All three si5351 outputs (and consequently the rig operating frequency) are locked into ratios of that 875mhz VCO.
So if operating at 10mhz, the operating frequency is 875mhz/87.5=10mhz, and the calibration granularity is 875hz/87.5 = 10hz.
And if operating at 30mhz, then the calibration granularity is 30hz, given the 875hz step size of the code in ubitx_setup.ino.

A step size of 875 should be fine for most, but there is nothing special about it.
You could change the value of 875 in ubitx_setup.ino to anything you want, and recompile.
Larger step sizes will make calibration proceed faster, smaller step sizes will allow you to set the frequency more accurately.
Though to be very accurate, you will need to monitor the audio with a scope, and hope any DC blocking caps in the audio chain
will pass low enough frequencies.    (I haven't looked too hard at the code yet, I assume he is moving the BFO into
the center of the IF filter passband so you can hear a proper zero beat at very low audio frequencies.)

Calibrate using a signal source at the highest frequency for which it is convenient.
Calibrating to WWV at 10mhz will be 10 times more accurate than calibrating to an AM broadcast station at 1mhz.
Most AM shortwave broadcasting stations have a carrier within a hz or two of a 5khz increment.
If unsure how accurate that station is then verify by checking calibration against a different station.

This procedure was outlined in post 35235 over 2 years ago, when the uBitx was first announced.
Rather distressing to see all the posts in the forum from folks spending days trying to figure out how to calibrate.

Jerry, KE7ER

Cory King
 

“Replacement frequency source”.

So i picked up one of those NanoVNA’s on amazon and it can generate a constant signal on any given frequency.  I’m wondering how I can use that to set the BFO / calibration.

I have yet to find a concise YouTube video or guide on how one actually knows when the BFO and calibration are both set correctly.

my guess is for BFO I’m looking for the setting where the “tone” generated by VNA goes away— meaning the frequency on the dial is now sitting right on top of what would be the carrier.  But I could be completely wrong.


but seriously, the descriptions of “zero beat” I read online don’t click with me...   this stuff is all just math... surely somebody can describe it that way.

CR
 


So i picked up one of those NanoVNA’s on amazon and it can generate a constant signal on any given frequency.  I’m wondering how I can use that to set the BFO / calibration.  

Cory:

Unfortunately, the nanoVNAs are not accurate frequency generators, sometimes as much as 10 kHz off.

On Sat, Dec 14, 2019 at 3:29 PM Cory King <cory@...> wrote:

“Replacement frequency source”.

So i picked up one of those NanoVNA’s on amazon and it can generate a constant signal on any given frequency.  I’m wondering how I can use that to set the BFO / calibration.

I have yet to find a concise YouTube video or guide on how one actually knows when the BFO and calibration are both set correctly.

my guess is for BFO I’m looking for the setting where the “tone” generated by VNA goes away— meaning the frequency on the dial is now sitting right on top of what would be the carrier.  But I could be completely wrong.


but seriously, the descriptions of “zero beat” I read online don’t click with me...   this stuff is all just math... surely somebody can describe it that way.

CR
 




Retraction: Unfortunately, the nanoVNAs are not accurate frequency generators, sometimes as much as 10 kHz off.

I just checked my nanoVNA at HF. It was right on target. I must be remembering its performance at SHF.


On Sun, Dec 15, 2019 at 10:24 AM CR via Groups.Io <maccluer13=gmail.com@groups.io> wrote:

So i picked up one of those NanoVNA’s on amazon and it can generate a constant signal on any given frequency.  I’m wondering how I can use that to set the BFO / calibration.  

Cory:

Unfortunately, the nanoVNAs are not accurate frequency generators, sometimes as much as 10 kHz off.

On Sat, Dec 14, 2019 at 3:29 PM Cory King <cory@...> wrote:

“Replacement frequency source”.

So i picked up one of those NanoVNA’s on amazon and it can generate a constant signal on any given frequency.  I’m wondering how I can use that to set the BFO / calibration.

I have yet to find a concise YouTube video or guide on how one actually knows when the BFO and calibration are both set correctly.

my guess is for BFO I’m looking for the setting where the “tone” generated by VNA goes away— meaning the frequency on the dial is now sitting right on top of what would be the carrier.  But I could be completely wrong.


but seriously, the descriptions of “zero beat” I read online don’t click with me...   this stuff is all just math... surely somebody can describe it that way.