1. BITX20@groups.io
   Date   
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Ashhar Farhan
 

Since we noticed these problems, we do check for the presence of these tones. Our pass test includes viewing the audio spectrum at 5v/db, 625 hz per division setting of FFT on rigol. We set the carrier so that the audio passband is inside two cursors at 300 hz and 3000 hz. Then we check for any spurs upto 15 khz that are above the noise floor. If these tests pass, we move to the next test of transmit outputs on 3.5, 7, 14 and 28 mhz. These tests are a part of the firmware being shipped.

I suspect the 16 mhz crystal must have aged. There are two things you can try. First is go into the bfo settings and move it slightly so the spurs go away. Second is to add some capacitance to the 25 mhz crystal, about 10 pf. There is a third way too, which is to program the si5352 initialization code to enable a different load capacitance on oscillator. I havent tried the third method myself.

Very often, closed commercial designs tend to ignore or bury design faults. Open source proceeds with acknowledgment and fixing these to make the system better. As the saying goes, given enough eyeballs, all bugs are shallow.

- f

On 3 Feb 2018 4:19 am, "Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:
HFO's being off suggests the 25mhz crystal at the si5351 might be the problem on this one.
Regardless, it is probably a matter of 3'rd harmonic of the 16mhz nano oscillator
beating with the fourth harmonic 1.9985mhz bfo.
Tone should change when you bring your finger close to the very very dinky crystal near the nano's processor.
Will likely change when you bring your finger near the 25mhz ref crystal near the si5351 also.

I'd take a calibrated SW receiver, listen for the 16 and 25mhz oscillators, see if one is off frequency
then maybe try swapping out just that crystal.    Especially if that signal seems somewhat unstable.
A crystal in an entirely different package will probably work  if you keep the wires short.

If the 25mhz reference oscillator were unstable, that would make the ubitx receiver unstable also,
which I assume is not the case.  So best guess is John's 16mhz crystal near the Nano.

What exactly do you mean by "HFOs were off far enough to effect the signal by 8dB."
So, perhaps your BFO as shipped from HFSignals was far enough from the 12mhz crystal ladder filter
that signals were down by 8dB?  Or perhaps you updated your firmware, and lost the HFSignals calibration?

Jerry

On Fri, Feb 2, 2018 at 02:04 pm, Dave Bottom wrote:
John,
 
Thanks for your hard work.  My uBITX has the same exact issue with the "squeal".  Mine did not originally have this issue until a couple of weeks ago (received Dec 22) and now it has gotten worse over that time.
 
It is interesting that the HFOs were off far enough to effect the signal by 8dB. Something to check and maybe this should be part of alignment for each radio?  At least with a spectrum analyzer this won't be too hard.
Yes interested in your code for this test.  
 
So now when I have time I know what to try, although it doesn't sound like much fun changing the Nano.
 
Dave WI6R
 
Re: uBITX AGC - Adafruit TPA2016, A Success! #ubitx

Nick VK4PP
 

Hi john, both boards from eBay...
I am really happy with the setup, AGC is performing very well in my opinion...
Re: uBITX AM BCI Filter #ubitx

Nick VK4PP
 

My filerf implementation:
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Gordon Gibby <ggibby@...>
 

I have programmed the initialization for various capacitances on the 25MHz Crystal, and it works, but if I remember correctly it didn’t move the frequency a whole lot.  However, since you’re looking at harmonics it might be enough.


On Feb 2, 2018, at 21:10, Ashhar Farhan <farhanbox@...> wrote:

Since we noticed these problems, we do check for the presence of these tones. Our pass test includes viewing the audio spectrum at 5v/db, 625 hz per division setting of FFT on rigol. We set the carrier so that the audio passband is inside two cursors at 300 hz and 3000 hz. Then we check for any spurs upto 15 khz that are above the noise floor. If these tests pass, we move to the next test of transmit outputs on 3.5, 7, 14 and 28 mhz. These tests are a part of the firmware being shipped.

I suspect the 16 mhz crystal must have aged. There are two things you can try. First is go into the bfo settings and move it slightly so the spurs go away. Second is to add some capacitance to the 25 mhz crystal, about 10 pf. There is a third way too, which is to program the si5352 initialization code to enable a different load capacitance on oscillator. I havent tried the third method myself.

Very often, closed commercial designs tend to ignore or bury design faults. Open source proceeds with acknowledgment and fixing these to make the system better. As the saying goes, given enough eyeballs, all bugs are shallow.

- f

On 3 Feb 2018 4:19 am, "Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:
HFO's being off suggests the 25mhz crystal at the si5351 might be the problem on this one.
Regardless, it is probably a matter of 3'rd harmonic of the 16mhz nano oscillator
beating with the fourth harmonic 1.9985mhz bfo.
Tone should change when you bring your finger close to the very very dinky crystal near the nano's processor.
Will likely change when you bring your finger near the 25mhz ref crystal near the si5351 also.

I'd take a calibrated SW receiver, listen for the 16 and 25mhz oscillators, see if one is off frequency
then maybe try swapping out just that crystal.    Especially if that signal seems somewhat unstable.
A crystal in an entirely different package will probably work  if you keep the wires short.

If the 25mhz reference oscillator were unstable, that would make the ubitx receiver unstable also,
which I assume is not the case.  So best guess is John's 16mhz crystal near the Nano.

What exactly do you mean by "HFOs were off far enough to effect the signal by 8dB."
So, perhaps your BFO as shipped from HFSignals was far enough from the 12mhz crystal ladder filter
that signals were down by 8dB?  Or perhaps you updated your firmware, and lost the HFSignals calibration?

Jerry

On Fri, Feb 2, 2018 at 02:04 pm, Dave Bottom wrote:
John,
 
Thanks for your hard work.  My uBITX has the same exact issue with the "squeal".  Mine did not originally have this issue until a couple of weeks ago (received Dec 22) and now it has gotten worse over that time.
 
It is interesting that the HFOs were off far enough to effect the signal by 8dB. Something to check and maybe this should be part of alignment for each radio?  At least with a spectrum analyzer this won't be too hard.
Yes interested in your code for this test.  
 
So now when I have time I know what to try, although it doesn't sound like much fun changing the Nano.
 
Dave WI6R
 
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Jerry Gaffke
 

 Adding a cap across the 25mhz crystal (or adjusting the loading capacitance in the si5352 initialization code)
and going into calibration and adjusting the bfo setting both do the same thing.
They move the BFO frequency a bit down, further away from the 12mhz crystal filter passband.
(I'm assuming this 16mhz harmonic is above the 12mhz harmonic, as most raduinos have it)

I'd recommend trying the latter, as it is simpler. 
But however you do it, transmit and receive audio will change, becoming higher pitched.

I think the ideal solution would be to move the 16mhz Nano oscillator by a few khz.
If we're lucky, we can add capacitance in parallel with it and move it well below 16mhz.
Unfortunately it will have to move pretty far, as that 3'rd harmonic is going from above
the 4'th harmonic of the bfo (at 48mhz) to below the bfo harmonic. 
Pushing the 16mhz crystal up in frequency is more difficult to do, perhaps a series inductor.

Replacing the 16mhz crystal entirely might be best.
The max spec for the ATMega328P is 16mhz, so if it's a significantly different freq it should be lower.
Hard to get in the dinky form factor used on the Nano, but other crystal package sizes would be fine
if you hot glue it to the board and use short wires, being careful to keep the crystal case insulated.

Mouser has their 449-LFXTAL002057BULK which is 15.625mhz in stock, quite cheap and relatively small.
Also 449-LFXTAL003555BULK which is 15.81mhz, somewhat bigger.
Mouser 449-LFXTAL012514BULK is at 16.02355, I doubt the ATMega328P would notice it being out of spec.
That last one looks best to me.

The ones I show above are all pretty big physically, you might shop for smaller

Another possibility is to shield the Nano as best you can, try to keep that 16mhz from getting to the radio.
Perhaps grounding the 16mhz crystal case is all that is needed.
I doubt there is much 16mhz floating around there except the at the crystal and the two ATMega328P pins
that go to the crystal.

Jerry


On Fri, Feb 2, 2018 at 06:10 pm, Ashhar Farhan wrote:
I suspect the 16 mhz crystal must have aged. There are two things you can try. First is go into the bfo settings and move it slightly so the spurs go away. Second is to add some capacitance to the 25 mhz crystal, about 10 pf. There is a third way too, which is to program the si5352 initialization code to enable a different load capacitance on oscillator. I havent tried the third method myself.
 
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

John Backo
 

Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...

john
AD5YE
Re: uBITX AM BCI Filter #ubitx

Mike Woods
 

Nick

Looks good!   Have you cut tracks or removed parts?  Can you describe exactly where this has been inserted as I want to feature this on the ubitx.net website to help others insert a BCI filter in the RX input line.

73 Mike ZL1AXG

On 3/02/18 3:19 PM, Nick VK4PLN wrote:
My filerf implementation:


--
Mike Woods
mhwoods@...
Re: AE7EU Top mod update

Diver Martin <diver.martin@...>
 

Well, damn if I didn't check the schematic like 15 times.  Apparently I ordered MCP601T's instead of MCP601RT's.  The difference?  VDD and VSS are swapped.

Explains why at 3V the current use went to 1A+.  Removing the two MCP601T's brought everything up.  So, no smoke at 12V now...  Baby steps!  The AGC mod will have to wait until I get parts in next week, but I can start debugging and programming other features in the meantime...


On Fri, Feb 2, 2018 at 11:11 AM, N8DAH <Dherron@...> wrote:
Looks great!
--
David

 N8DAH
Kit-Projects.com




--
Martin Held - AE7EU
http://ae7eu.com/
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Jerry Gaffke
 

Kind of murky, but I think the ATMega328P on the Nano has a max crystal freq of 16mhz.
My datasheet in section 9-3 says 16mhz max when using the "Low Power Crystal Oscillator",
in section 9-4 says 20mhz max when using the "Full Swing Crystal Oscillator".
My guess is that the Arduino set-up routines use the Low Power Crystal Oscillator.
And this document says the Full Swing Crystal Oscillator is going away:
    http://img.digikey.com/Retractions/WC154601%20-%20PCN-12-23-2015.pdf

Significant changes to the crystal frequency will affect timing, things like keyer speed
and delays in closing relays.  Easily fixed, but will require a new sketch.

The 328P on the Nano does operate from a 5v rail. 
(Even when executing Arduino code.)

Adjusting the BFO freq may help the tones, but is not a good solution
because this also affects the range of audio frequencies on receive or transmit
as mentioned in my previous post.
 
Curious that the Bitx40v3 never had this problem, it had the same 16mhz Nano clock and 12mhz BFO
And the BFO was commonly placed both above and below the crystal filter passband.
Perhaps lack of trouble was due to the physical separation the Nano had from the modulator.
On the uBitx, the modulator is right next to the Nano and si5351, which is good because
it ensures clean consistent clocks from the si5351 get to the mixers, but bad if the Nano's 16mhz
throws a monkey wrench into the works.  

If physical separation works on the Bitx40v3, then some simple shielding may work on the uBitx.
Perhaps just a piece of tinfoil or copper sheet taped over the modulator, grounded but otherwise insulated. 

Additional power supply filtering on the Nano may be help, as John suggested.
And caps to ground on the control signals from Nano to uBitx main board.

Would be interesting to move the uBitx BFO to the high side of the crystal filter, closer to 12mhz.
The tones will likely show up on most any uBitx, allowing countermeasures to be tested.

Currently the uBitx BFO is always below the crystal filter to avoid the tones, second LO always at 45-12mhz
Would be nice to  be able to switch sidebands by flipping the BFO to high or low side.
Could then have the second LO at either 45+12 or 45-12mhz, whichever gives fewer birdies
and other such artifacts. 

Jerry



On Fri, Feb 2, 2018 at 07:43 pm, John Backo wrote:
Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Ashhar Farhan
 

changing the arudino cap is going to be a challenge as the arduino is soldered and you need to access it from the underside to desolder it. we had to resort to solder it in as keep it on a socket was leading to bulge and an additional failure point on the board.

- f

On Sat, Feb 3, 2018 at 1:18 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Kind of murky, but I think the ATMega328P on the Nano has a max crystal freq of 16mhz.
My datasheet in section 9-3 says 16mhz max when using the "Low Power Crystal Oscillator",
in section 9-4 says 20mhz max when using the "Full Swing Crystal Oscillator".
My guess is that the Arduino set-up routines use the Low Power Crystal Oscillator.
And this document says the Full Swing Crystal Oscillator is going away:
    http://img.digikey.com/Retractions/WC154601%20-%20PCN-12-23-2015.pdf

Significant changes to the crystal frequency will affect timing, things like keyer speed
and delays in closing relays.  Easily fixed, but will require a new sketch.

The 328P on the Nano does operate from a 5v rail. 
(Even when executing Arduino code.)

Adjusting the BFO freq may help the tones, but is not a good solution
because this also affects the range of audio frequencies on receive or transmit
as mentioned in my previous post.
 
Curious that the Bitx40v3 never had this problem, it had the same 16mhz Nano clock and 12mhz BFO
And the BFO was commonly placed both above and below the crystal filter passband.
Perhaps lack of trouble was due to the physical separation the Nano had from the modulator.
On the uBitx, the modulator is right next to the Nano and si5351, which is good because
it ensures clean consistent clocks from the si5351 get to the mixers, but bad if the Nano's 16mhz
throws a monkey wrench into the works.  

If physical separation works on the Bitx40v3, then some simple shielding may work on the uBitx.
Perhaps just a piece of tinfoil or copper sheet taped over the modulator, grounded but otherwise insulated. 

Additional power supply filtering on the Nano may be help, as John suggested.
And caps to ground on the control signals from Nano to uBitx main board.

Would be interesting to move the uBitx BFO to the high side of the crystal filter, closer to 12mhz.
The tones will likely show up on most any uBitx, allowing countermeasures to be tested.

Currently the uBitx BFO is always below the crystal filter to avoid the tones, second LO always at 45-12mhz
Would be nice to  be able to switch sidebands by flipping the BFO to high or low side.
Could then have the second LO at either 45+12 or 45-12mhz, whichever gives fewer birdies
and other such artifacts. 

Jerry



On Fri, Feb 2, 2018 at 07:43 pm, John Backo wrote:
Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...


Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Ashhar Farhan
 

The best solution is to move the IF to 11 MHz. The caps will remain the same, the crystals will have to change.

-- f

On Sat, Feb 3, 2018 at 1:25 PM, Ashhar Farhan <farhanbox@...> wrote:
changing the arudino cap is going to be a challenge as the arduino is soldered and you need to access it from the underside to desolder it. we had to resort to solder it in as keep it on a socket was leading to bulge and an additional failure point on the board.

- f

On Sat, Feb 3, 2018 at 1:18 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Kind of murky, but I think the ATMega328P on the Nano has a max crystal freq of 16mhz.
My datasheet in section 9-3 says 16mhz max when using the "Low Power Crystal Oscillator",
in section 9-4 says 20mhz max when using the "Full Swing Crystal Oscillator".
My guess is that the Arduino set-up routines use the Low Power Crystal Oscillator.
And this document says the Full Swing Crystal Oscillator is going away:
    http://img.digikey.com/Retractions/WC154601%20-%20PCN-12-23-2015.pdf

Significant changes to the crystal frequency will affect timing, things like keyer speed
and delays in closing relays.  Easily fixed, but will require a new sketch.

The 328P on the Nano does operate from a 5v rail. 
(Even when executing Arduino code.)

Adjusting the BFO freq may help the tones, but is not a good solution
because this also affects the range of audio frequencies on receive or transmit
as mentioned in my previous post.
 
Curious that the Bitx40v3 never had this problem, it had the same 16mhz Nano clock and 12mhz BFO
And the BFO was commonly placed both above and below the crystal filter passband.
Perhaps lack of trouble was due to the physical separation the Nano had from the modulator.
On the uBitx, the modulator is right next to the Nano and si5351, which is good because
it ensures clean consistent clocks from the si5351 get to the mixers, but bad if the Nano's 16mhz
throws a monkey wrench into the works.  

If physical separation works on the Bitx40v3, then some simple shielding may work on the uBitx.
Perhaps just a piece of tinfoil or copper sheet taped over the modulator, grounded but otherwise insulated. 

Additional power supply filtering on the Nano may be help, as John suggested.
And caps to ground on the control signals from Nano to uBitx main board.

Would be interesting to move the uBitx BFO to the high side of the crystal filter, closer to 12mhz.
The tones will likely show up on most any uBitx, allowing countermeasures to be tested.

Currently the uBitx BFO is always below the crystal filter to avoid the tones, second LO always at 45-12mhz
Would be nice to  be able to switch sidebands by flipping the BFO to high or low side.
Could then have the second LO at either 45+12 or 45-12mhz, whichever gives fewer birdies
and other such artifacts. 

Jerry



On Fri, Feb 2, 2018 at 07:43 pm, John Backo wrote:
Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...



Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

MVS Sarma
 

Farhan jee
You mean 11.0592....MHz
 Can one use (MHz as most rigs had ssb filters around that? Of course with needed changes in Raduino.
regards
 sarma
 vu3zmv

Regards
MVS Sarma
 

On Sat, Feb 3, 2018 at 1:27 PM, Ashhar Farhan <farhanbox@...> wrote:
The best solution is to move the IF to 11 MHz. The caps will remain the same, the crystals will have to change.

-- f

On Sat, Feb 3, 2018 at 1:25 PM, Ashhar Farhan <farhanbox@...> wrote:
changing the arudino cap is going to be a challenge as the arduino is soldered and you need to access it from the underside to desolder it. we had to resort to solder it in as keep it on a socket was leading to bulge and an additional failure point on the board.

- f

On Sat, Feb 3, 2018 at 1:18 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Kind of murky, but I think the ATMega328P on the Nano has a max crystal freq of 16mhz.
My datasheet in section 9-3 says 16mhz max when using the "Low Power Crystal Oscillator",
in section 9-4 says 20mhz max when using the "Full Swing Crystal Oscillator".
My guess is that the Arduino set-up routines use the Low Power Crystal Oscillator.
And this document says the Full Swing Crystal Oscillator is going away:
    http://img.digikey.com/Retractions/WC154601%20-%20PCN-12-23-2015.pdf

Significant changes to the crystal frequency will affect timing, things like keyer speed
and delays in closing relays.  Easily fixed, but will require a new sketch.

The 328P on the Nano does operate from a 5v rail. 
(Even when executing Arduino code.)

Adjusting the BFO freq may help the tones, but is not a good solution
because this also affects the range of audio frequencies on receive or transmit
as mentioned in my previous post.
 
Curious that the Bitx40v3 never had this problem, it had the same 16mhz Nano clock and 12mhz BFO
And the BFO was commonly placed both above and below the crystal filter passband.
Perhaps lack of trouble was due to the physical separation the Nano had from the modulator.
On the uBitx, the modulator is right next to the Nano and si5351, which is good because
it ensures clean consistent clocks from the si5351 get to the mixers, but bad if the Nano's 16mhz
throws a monkey wrench into the works.  

If physical separation works on the Bitx40v3, then some simple shielding may work on the uBitx.
Perhaps just a piece of tinfoil or copper sheet taped over the modulator, grounded but otherwise insulated. 

Additional power supply filtering on the Nano may be help, as John suggested.
And caps to ground on the control signals from Nano to uBitx main board.

Would be interesting to move the uBitx BFO to the high side of the crystal filter, closer to 12mhz.
The tones will likely show up on most any uBitx, allowing countermeasures to be tested.

Currently the uBitx BFO is always below the crystal filter to avoid the tones, second LO always at 45-12mhz
Would be nice to  be able to switch sidebands by flipping the BFO to high or low side.
Could then have the second LO at either 45+12 or 45-12mhz, whichever gives fewer birdies
and other such artifacts. 

Jerry



On Fri, Feb 2, 2018 at 07:43 pm, John Backo wrote:
Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...




Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Ashhar Farhan
 

yes, sarma-ji.
- f

On Sat, Feb 3, 2018 at 1:30 PM, Mvs Sarma <mvssarma@...> wrote:
Farhan jee
You mean 11.0592....MHz
 Can one use (MHz as most rigs had ssb filters around that? Of course with needed changes in Raduino.
regards
 sarma
 vu3zmv

Regards
MVS Sarma
 

On Sat, Feb 3, 2018 at 1:27 PM, Ashhar Farhan <farhanbox@...> wrote:
The best solution is to move the IF to 11 MHz. The caps will remain the same, the crystals will have to change.

-- f

On Sat, Feb 3, 2018 at 1:25 PM, Ashhar Farhan <farhanbox@...> wrote:
changing the arudino cap is going to be a challenge as the arduino is soldered and you need to access it from the underside to desolder it. we had to resort to solder it in as keep it on a socket was leading to bulge and an additional failure point on the board.

- f

On Sat, Feb 3, 2018 at 1:18 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Kind of murky, but I think the ATMega328P on the Nano has a max crystal freq of 16mhz.
My datasheet in section 9-3 says 16mhz max when using the "Low Power Crystal Oscillator",
in section 9-4 says 20mhz max when using the "Full Swing Crystal Oscillator".
My guess is that the Arduino set-up routines use the Low Power Crystal Oscillator.
And this document says the Full Swing Crystal Oscillator is going away:
    http://img.digikey.com/Retractions/WC154601%20-%20PCN-12-23-2015.pdf

Significant changes to the crystal frequency will affect timing, things like keyer speed
and delays in closing relays.  Easily fixed, but will require a new sketch.

The 328P on the Nano does operate from a 5v rail. 
(Even when executing Arduino code.)

Adjusting the BFO freq may help the tones, but is not a good solution
because this also affects the range of audio frequencies on receive or transmit
as mentioned in my previous post.
 
Curious that the Bitx40v3 never had this problem, it had the same 16mhz Nano clock and 12mhz BFO
And the BFO was commonly placed both above and below the crystal filter passband.
Perhaps lack of trouble was due to the physical separation the Nano had from the modulator.
On the uBitx, the modulator is right next to the Nano and si5351, which is good because
it ensures clean consistent clocks from the si5351 get to the mixers, but bad if the Nano's 16mhz
throws a monkey wrench into the works.  

If physical separation works on the Bitx40v3, then some simple shielding may work on the uBitx.
Perhaps just a piece of tinfoil or copper sheet taped over the modulator, grounded but otherwise insulated. 

Additional power supply filtering on the Nano may be help, as John suggested.
And caps to ground on the control signals from Nano to uBitx main board.

Would be interesting to move the uBitx BFO to the high side of the crystal filter, closer to 12mhz.
The tones will likely show up on most any uBitx, allowing countermeasures to be tested.

Currently the uBitx BFO is always below the crystal filter to avoid the tones, second LO always at 45-12mhz
Would be nice to  be able to switch sidebands by flipping the BFO to high or low side.
Could then have the second LO at either 45+12 or 45-12mhz, whichever gives fewer birdies
and other such artifacts. 

Jerry



On Fri, Feb 2, 2018 at 07:43 pm, John Backo wrote:
Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...





Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

John Backo
 

I substituted 11.092 MHz for 10 MHz in a build of the BITX v.3.

It decoded both 40m and 20m very well, just by changing the
BFO from LO to HI. And the VFO had to be spread out a bit.
Of course, 40m tuned in reverse, but it works..

I figured out that the best IF would be ~10.5 MHz as this gives nearly
a symmetric VFO/BFO mirror (in the spirit of the 9 MHz 20/80m classic rig).
But such crystals are unobtanium. Hi.

john
AD5YE
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

Jerry Gaffke
 

I assume you mean changing the Arduino crystal, not cap.

The 16mhz ATMega328P crystal is about 3mm x 1.5mm, goes to  ATMega328p pins 7 and 8.
It is on the top of the Nano, just above the silk for edge pin D5.
Seeing the actual crystal now, and not just looking at datasheets and schematics, I see that it is
extremely small.   I doubt most of those with uBitx in hand will want to mess with it.

I bought some spare Nano clones, I believe they're identical to what's on the Raduino.
Mine have a CH340G chip on the back of the Nano for the USB interface.
This chip has another 3mm x 1.5mm crystal nearby, this one happens to be 12mhz.
    http://www.datasheet5.com/pdf-local-2195953

Quite possibly it is the 12mhz oscillator for the USB interface that is causing the trouble in at least some cases.
Though in post 40432 it was reported that a finger on the Nano's crystal caused the tones to vary,
which suggests that case was due to the 16mhz crystal since the 12mhz crystal is not usually accessible.

None of this was ever a problem on the Bitx40v3, far as I know.
I'd like to think there will be a simple fix, perhaps soldering in a bit of copper tape somewhere for shielding,
or adding a few caps.    Moving the IF would be pretty disruptive.

Jerry



On Fri, Feb 2, 2018 at 11:55 pm, Ashhar Farhan wrote:
changing the arudino cap is going to be a challenge as the arduino is soldered and you need to access it from the underside to desolder it. we had to resort to solder it in as keep it on a socket was leading to bulge and an additional failure point on the board.
 
Re: #ubitx-help Strong Audio Tones in and outside audio receive passband #ubitx-help

MVS Sarma
 

sorry for my typing sir. I meant 9MHz crystal ladder filter.


Regards
MVS Sarma
 

On Sat, Feb 3, 2018 at 1:35 PM, Ashhar Farhan <farhanbox@...> wrote:
yes, sarma-ji.
- f

On Sat, Feb 3, 2018 at 1:30 PM, Mvs Sarma <mvssarma@...> wrote:
Farhan jee
You mean 11.0592....MHz
 Can one use (MHz as most rigs had ssb filters around that? Of course with needed changes in Raduino.
regards
 sarma
 vu3zmv

Regards
MVS Sarma
 

On Sat, Feb 3, 2018 at 1:27 PM, Ashhar Farhan <farhanbox@...> wrote:
The best solution is to move the IF to 11 MHz. The caps will remain the same, the crystals will have to change.

-- f

On Sat, Feb 3, 2018 at 1:25 PM, Ashhar Farhan <farhanbox@...> wrote:
changing the arudino cap is going to be a challenge as the arduino is soldered and you need to access it from the underside to desolder it. we had to resort to solder it in as keep it on a socket was leading to bulge and an additional failure point on the board.

- f

On Sat, Feb 3, 2018 at 1:18 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Kind of murky, but I think the ATMega328P on the Nano has a max crystal freq of 16mhz.
My datasheet in section 9-3 says 16mhz max when using the "Low Power Crystal Oscillator",
in section 9-4 says 20mhz max when using the "Full Swing Crystal Oscillator".
My guess is that the Arduino set-up routines use the Low Power Crystal Oscillator.
And this document says the Full Swing Crystal Oscillator is going away:
    http://img.digikey.com/Retractions/WC154601%20-%20PCN-12-23-2015.pdf

Significant changes to the crystal frequency will affect timing, things like keyer speed
and delays in closing relays.  Easily fixed, but will require a new sketch.

The 328P on the Nano does operate from a 5v rail. 
(Even when executing Arduino code.)

Adjusting the BFO freq may help the tones, but is not a good solution
because this also affects the range of audio frequencies on receive or transmit
as mentioned in my previous post.
 
Curious that the Bitx40v3 never had this problem, it had the same 16mhz Nano clock and 12mhz BFO
And the BFO was commonly placed both above and below the crystal filter passband.
Perhaps lack of trouble was due to the physical separation the Nano had from the modulator.
On the uBitx, the modulator is right next to the Nano and si5351, which is good because
it ensures clean consistent clocks from the si5351 get to the mixers, but bad if the Nano's 16mhz
throws a monkey wrench into the works.  

If physical separation works on the Bitx40v3, then some simple shielding may work on the uBitx.
Perhaps just a piece of tinfoil or copper sheet taped over the modulator, grounded but otherwise insulated. 

Additional power supply filtering on the Nano may be help, as John suggested.
And caps to ground on the control signals from Nano to uBitx main board.

Would be interesting to move the uBitx BFO to the high side of the crystal filter, closer to 12mhz.
The tones will likely show up on most any uBitx, allowing countermeasures to be tested.

Currently the uBitx BFO is always below the crystal filter to avoid the tones, second LO always at 45-12mhz
Would be nice to  be able to switch sidebands by flipping the BFO to high or low side.
Could then have the second LO at either 45+12 or 45-12mhz, whichever gives fewer birdies
and other such artifacts. 

Jerry



On Fri, Feb 2, 2018 at 07:43 pm, John Backo wrote:
Actually, one could substitute any crystal from 8 MHz
to probably 20 MHz. Theoretically, running the arduino
changes the voltages to about 3.3v, but I and others have
noticed it works fine on 8 MHz and 5v. I would avoid anything
around 12 MHz as that is the USB frequency range and might
interfere. Easily had is a 10 MHz crystal which would probably work
fine. Even a HC49S type would work with just one jumper wire for
one lead (or maybe soldered direct), and the other pin soldered directly.
The old crystal would. of course, need to be removed.

A simple solution is to do what Jerry suggests, and change the BFO
frequency slightly. That may or may not cure the "symptoms"; it certainly
will not cure the problem.

It is likely that uPC crystal radiation is the problem, however. But it may be coming
from inside the radiuno itself. Sometimes (often) this because of Rf leakage back
through the power supply; make sure that is well filtered. Farhan's suggestion
of crystal aging is also very apropos.

Probably the next simplest solution is to replace the nano...






Re: uBITX AM BCI Filter #ubitx

Nick VK4PP
 

HI Mike and the group.

Yes I cut the trace either side of the new HPF board, exposed a bit of the trace and jumperd onto that.
You need to cut the second trace from the PA side. They are in order:
1: TX pwr to the PA circuits via R89
2: RX path (between K1 and K3 relays. (CUT AND INSERT HERE)
3: TX pwr to the LPF bank.
4: RX pwr to the receive circuit (R18,R38...)

I picked up GND from the 2 unused caps C216 and C210
Filter Details: https://groups.io/g/BITX20/wiki/uBITX-AM-BCI-Filter

73, Nick. VK4PLN
Nextion display

Dr Fred Hambrecht
 

For those that may be considering the Nextion display, let me suggest you start out by going to their website Https://nextion.itead.cc On the home page select download and select the Nextion editor.
This will give you a chance to play without spending any money on buying the actual display but allows you simulate the display and see if it meets your needs.

V/R
Fred W4JLE
Re: uBITX AGC - Adafruit TPA2016, A Success! #ubitx

John <passionfruit88@...>
 

Thanks Nick.

73, John
BitX40 v1.27.7 SPOT mode

Vic WA4THR
 

I am using Allard's wonderful v1.27.7 sketch in my BitX40, and because of an trip planned this weekend was rushing to package it so it could be used. I have added the PTT sense line, a FCN switch, and a SPOT switch, and have significantly shortened leads in this final package. Everything seems to be working well and I was able to use the rig mobile. When I press SPOT I am able to fine tune in LSB mode very easily, but the frequency displayed in SPOT mode differs from what the normal display shows. For example, if I am on 7.255.00 and press SPOT, the display reads 7.254.955, so if I tune that to 7.255.00 and release SPOT I get 7.255.05 on the normal display. Am I doing something wrong? Is there some sort of offset in LSB SPOT that needs to be adjusted?

 

73, =Vic=

WA4THR