Date   
Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

Thanks to both of you.

I first tried to change C67 to 22pF as suggested by Steven. I did not see a difference at all, so I skipped the 2nd suggestion (changing it to a resistor) and went immediatelly
to Don's idea about changing everything (C60-62 and C67) to 10pF.

And that did the trick. Now i had the same output on USB and LSB ( I just noticed that in the SB1 C67 really was an 1k resistor - so this might havealso  been enough).

I know of course that there is no real usage for LSB on 20m, but since  this was the mode that worked, I used it for reference. I just needed something to compare to.


This change  also helped a lot with the RX sensitivity. Today I used the calibration station and did some measurements. I can at least detect (not enough for anything more)
an incoming signal of about - 115 dbm. 

There is just one oddity - the receiver is always a bit more sensitive beneath the center frequency. As my calibration station is transmitting an AM-signal ( 1khz Audio-SIgnal)
this could also be related to that fact or it could be a filter thing.  I did the BFO calibration earlier, so it should be unrelated to that. But for now that is neclegtable.
It was just strange, that I could hear the signal stronger, if I tuned the SBII a bit lower (higher did nothing).

I also found out what the problem with the MOD-LED was. LED defect, resistance of 18k and no function. :-) As I did not have another red 3mm LED I changed it to yellow.
Now I get some flackering, but it is nearly nothing (even if the MOD poti is tuned fully to the right.. Maybe thats because red LEDs need less voltage than yellow.Minor problem.
I used a second receiver to check modulation and it seems okay.

I also noticed that maximal power in CW is about 5,5-6W. This is a bit less than stated in the manual of the SBII (10W - I think this is for 80 and 40m) and closer to the manual of the SB1 (7-8W),
but I can totally live with that :-)

It really was a lot of fun

Maybe I need a second one for 40m :-)

Re: Should I do another batch of Slop Bucket kits? #poll

ajparent1/kb1gmx
 

No, just barking dogs.

What happens is someone goes on the web version and sees
a topic and not the dates and replies.  That triggers emails
as that how most get it messages, and they start replying.
We then get a cascade about something started 6/2/2018.

Allison

Re: Should I do another batch of Slop Bucket kits? #poll

Dale Lam
 

What has happened to thte postings? It looks like there has been a groups io failure of some kind.
Dale Lam - NoOU

Re: Should I do another batch of Slop Bucket kits? #poll

ajparent1/kb1gmx
 

An aside, recent responses are to a posting over a year old.

Allison

New file uploaded to kd1jvdesigns@groups.io

kd1jvdesigns@groups.io Notification <kd1jvdesigns+notification@...>
 

Hello,

This email message is a notification to let you know that the following files have been uploaded to the Files area of the kd1jvdesigns@groups.io group.

Uploaded By: Steven Weber <steve.kd1jv@...>

Description:
20M LSB bug fix, Freq mem location fix, save SREG in interrupt timer.

Cheers,
The Groups.io Team

Re: SB II #112 nearly done / searching the last building mistakes

Steven Weber
 

Are you building this for 20 meters?

 

I see now I should have specified a smaller value for C67 for a 20M build. A bit too much attenuation for a 23 MHz LO. You could try changing it to 22 pfd or eliminate C67 and replace it with a 1 K resistor to get a consistent level regardless of frequency.

 

If you have not calibrated the oscillator, doing that will make a big difference. Without calibration, the BFO frequency can be off a few 100 Hz or more.

 

On 20M there is no real need for LSB, that option was added so FT8 could be used on 40, which requires USB.

 

Steve KD1JV

 

 

 

 

A quick look at the data sheet for the 74HC4053 shows that it probably is not the culprit. If you have four 10pF capacitors then it might be worthwhile replacing C60-62 and C67 (currently 47pF) with those. My modeling shows a better level balance with an improvement of 10dB on  23 MHz. 73, Don

_._,_._,_

 

Re: SB II #112 nearly done / searching the last building mistakes

Don, ND6T
 

A quick look at the data sheet for the 74HC4053 shows that it probably is not the culprit. If you have four 10pF capacitors then it might be worthwhile replacing C60-62 and C67 (currently 47pF) with those. My modeling shows a better level balance with an improvement of 10dB on  23 MHz. 73, Don

Re: SB II #112 nearly done / searching the last building mistakes

Don, ND6T
 

Sascha,

I agree. The higher BFO frequency is considerably weaker. This might be due to the frequency response of U4 but I wouldn't doubt that the capacitive dividers (C60-62, 67) might also contribute. Well worth investigating.

Optimizing the signal frequency within the crystal filter pass band is a good idea. First calibrate everything before trying that, of course. Both of my SB2 did not need it but they are on 80m and 40m. The Upper Sideband setting on 40m results in an appreciable loss of sensitivity but I never use this rig for digital modes.

Good work, Sascha. Thank you for sharing your adventure. Please keep us posted if you find more 20m solutions.
73,
Don

Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

Hi Don,

and - I am nearly done :-)  I found a bad solder connection on the capsule.

However I get lots auf audio on LSB und not so much on USB - or at least it looks that way when watching the power meter,
I could not listen to the signal yet with another radio.

Where I get 1W output by blowing in the mic on USB, I get 4-5W output on LSB.
The Mod LED does not flicker either, though I don't pay attention to that yet.

Is this maybe also caused by the redesign of the SB II from an original 20m USB to a 40m LSB radio?
Could this be related to the higher VFO frequency in USB (23,3 Mhz) than in LSB (4,9 MHz)?

I just tried to compare the source codes of the SB I and the SB II but did not find anything which could be causing this.

Or is this maybe a filter problem?

I noticed earlier that the radio is a bit deaf (only checked USB). It works, but signals need to be rather strong (S5) to be heard well.
I have not tried moving/adjusting the BFO signal to the IF FIlter yet - but if I look at the schematic, this could help as well with the transmitter, right?

Sascha

Re: SB II #112 nearly done / searching the last building mistakes

Don, ND6T
 

Hi Sascha,

No, the code was a rookie mistake. Although the brackets are optional when used with a single statement like that, I forgot that we are dealing with an unsigned integer. So it was not only an inelegant solution , it wasn't the right approach. I'll ponder it later. Your fix was perfect for the singular solution. Go pursue the audio. You have it in retreat! -Don-

Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

Hi Don

- that really was the problem.

Now I get about 10W Output on CW .

Still no SSB modulation but that is another problem I have to investigate. I will look into this matter tomorrow.

About your code snippet:

I tried it, but it did not work. Switched back to my other MC with the "hard wired change" and it was okay again.
Most probably there is only a small issue with it ( just noticed a missing curly bracket). I'll test tomorrow again.

Thanks  a lot for your guidance - I had a steep learning curve on this.

Sascha

Re: SB II #112 nearly done / searching the last building mistakes

Don, ND6T
 

Sascha,

I believe that you found it!
You might just add a line to the sketch to patch it to still work with the other bands like this third line:

 void PLLwrite() {
         VFOfreq = IFfreq - OPfreq;
           if((IFfreq - OPfreq)<1) VFOfreq = OPfreq - IFfreq; //Bug correction
         if (sideBand == 1) {VFOfreq =OPfreq + IFfreq;}
      if (Tx_mode == 1){VFOfreq = VFOfreq - 600;} 
          si5351bx_setfreq(0,VFOfreq);
                     }
I don't have a rig to test it at this time so please let us know if it works.
Congratulations.
Don

Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

So I just checked LSB - no VFO signal either.
Then I took a look at the code , line 600.

There is:
VFOfreq=  IFfreq - OPfreq
Is this really correct?
I think this works for 80, 60 and 40 - but on 20 Meters the VFO frequency gets negative. I don't think it is supposed to be this way.
I tried to put it in an abs() clause but this did not work out.

So I just changed it to OPfrequ - IFfrequ.
And this way I finally get a high level  VFO frequency at the test point.

I did not have a look at the mixers yet - but this should be right I think. Or not?
     }

Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

Hi Don - no problem.

As it was me who first confused BFO and VFO  I most probably caused your mixing up in the first place.

Once again its gets interesting now:

In SSB I can see the switching of the signals / frequencies at Pin 6 of both SA612 mixers and U4.
TXEN seems also to work in both modes, SSB and CW.

However I noticed now, that in CW the VFO does not seem to work correctly. Nearly no signal strength in CW (maybe 1 or 2 mV at the testpoint)
and the frequency seems to be the same or similar as the BFO.

Pictures CW : BFO 1, BFO2, VFO1 VFO2
Pictures SSB (USB) for reference: VFO1  VFO2

Seems like a firmware problem (why else should the VFO signal be present at the Testpoint in USB and not in CW?)
- though this should be impossible as it works in everybody else's rig.

I have flashed the latest firmware 1.2 two times and used two different microcontrollers, but it helped nothing.

Tomorrow I will check if the VFO also works in LSB. Maybe this gives some additional clues.

I read earlier that the SB 1 had earlier an issue with the BFO becoming the VFO frequency, 
induced by the BFO adjustment which called the wrong clock of the SI5351 - but this was solved.....

Or could this be a compiling issue - that something changed in the way the source file is interpreted?
I am using Arduino 1.8.9. with the libraries in the file section.

Maybe then my SSB mode is okay then and I have only an audio and CW problem? I am puzzled.

Clueless regards

Sascha


Re: SB II #112 nearly done / searching the last building mistakes

Don, ND6T
 

Sascha,

My apologies! U3 pin 6 should be the VFO! Looking at your photo I misread the finer trace as being high frequency, like the 23 MHz expected there, but reading the tool bar I see that it is the BFO frequency. Then I "caught" myself and corrected the text like the fool that I am.

This is probably the problem. The signals into pin 1 and pin 6 are supposed to mix and the results output from pin 4. Since both inputs are the same then that same frequency is output instead. I believe that the input to pin 6 should come from U4 pin 15 which is switched from (I believe) pins 1 and 2 of U4 by the TXEN (transmit enable) pins which are pins 9 and 10.

Check to see if that is happening. Check the solder connections on pins 9 and 10. Does the voltage change there when you key it? If not, follow the trace back to u8 pin 4 and check that connection.

There it is, my "inevitable mistake". :-)
73,
Don

Re: Soda Pop II #226 Arrived!

Gwen Patton
 

Even better!


On Fri, Feb 21, 2020 at 12:46 PM Steven Weber <steve.kd1jv@...> wrote:

The manual has a drill diagram with all the dimensions, so no need to measure.  

 

 

The kit arrived yesterday, and it's now in my queue to be constructed. I'm looking forward to this!

 

Does anyone have 3d print files for an enclosure? I've got a Creality Ender 3 sitting here, and I'd love to print up a nice case for this rig. If not, I'll have to haul out the calipers and rulers and design something in Tinkercad. If I have to do that, I'll probably put it on Thingiverse.

 

73,

Gwen, NG3P

 

 



--

-+-+-+-+-
Jenny Everywhere's Infinite: Quark Time
http://quarktime.net

Re: Soda Pop II #226 Arrived!

Steven Weber
 

The manual has a drill diagram with all the dimensions, so no need to measure.  

 

 

The kit arrived yesterday, and it's now in my queue to be constructed. I'm looking forward to this!

 

Does anyone have 3d print files for an enclosure? I've got a Creality Ender 3 sitting here, and I'd love to print up a nice case for this rig. If not, I'll have to haul out the calipers and rulers and design something in Tinkercad. If I have to do that, I'll probably put it on Thingiverse.

 

73,

Gwen, NG3P

 

 

Soda Pop II #226 Arrived!

Gwen Patton
 

The kit arrived yesterday, and it's now in my queue to be constructed. I'm looking forward to this!

Does anyone have 3d print files for an enclosure? I've got a Creality Ender 3 sitting here, and I'd love to print up a nice case for this rig. If not, I'll have to haul out the calipers and rulers and design something in Tinkercad. If I have to do that, I'll probably put it on Thingiverse.

73,
Gwen, NG3P

--

-+-+-+-+-
Jenny Everywhere's Infinite: Quark Time
http://quarktime.net

Re: SB II #112 nearly done / searching the last building mistakes

Don, ND6T
 

Hi Sascha,

We are getting closer.

According to the schematic:
The VFO is CLK0 on the Si5351 pin 10 and it connects to R45.
The BFO is CLK1 and that connects to R46
On 20m the BFO is 9.2169 MHz and the VFO is the sum of the operating frequency and the BFO (ie: @14.16 MHz SSB the VFO=23.3769 MHz).
For CW the BFO frequency is adjusted 600 Hz lower.

I do not have a 20m SB2 here that I can open and measure. I repaired one for a fellow but returned it. I may have one shortly if I am unable to help him on line. I can be more definitive if that happens.

I would not be concerned with the levels that you measure at the Si5351 outputs but you should have the 14 MHz signal on pin 4 but instead you are seeing the VFO frequency as it has passed through the crystal filter and into the mixer. The signal that you see on pin 6 of U3 is, indeed, the BFO.

You stated that the receive is working properly. Since U3 is the product detector in receive mode then it must be mixing at that time. So let's pursue the transmit path some more: While transmitting CW, check the signal at pin 1 of U3. That's the input. If it is very low then check at the junction of Q12 emitter, C47, and R28. That is the input to the crystal filter. You measured 9.213 MHz for that signal and that is 3.3 KHz lower than expected and would place it out of the filter band pass. If the SB2 has not been calibrated then that would explain it. If your oscilloscope can be trusted to be properly calibrated then that, too, should be considered.

If the receiver is NOT working properly then check that U3 pin 8 is +5 volts, pin 3 is well grounded, the bias on pin 1 and 2 are about equal, and that very little or no signal appears on pin 2 (it's a differential input, as I recall, and without C37 the signal will cancel itself).

The output of U3 pin 5 is bypassed to ground by C59. So, on receive when that output is audio, you will see detected audio (which that capacitor ignores). On transmit, that capacitor shorts the RF to ground so you shouldn't see much there.

I am pretty much "talking through my hat" here, Sascha. So forgive my inevitable mistakes. I am only guessing at things so accept my advice for what little it is worth ;-)
73,
Don

Re: SB II #112 nearly done / searching the last building mistakes

Sascha Bohnet | DL5SMB
 

Hi everybody and especially Don,

I am still working on this - I did some experiments in the meantime, completley rebuild the output LPF (which did nothing at all)
and then used another scope to check the frequencies.

I think I have a frequency problem, though I do not understand the schematic completly. I assume that my signal is only the VFO frequency which
gets filtered out again by the band / low pass filters so that nothing is left anymore.


First question ahead: Is it normal, that the VFO (Picture 1 and Picture 2)  and the BFO (Picture 1 and Picture 2) have different signal levels?
At the VFO I am seeing about 1,1V while the BFO seems to have around 0,5 Volt in SSB?

Is this supposed to be this way? I tried to resolder Pin 10 of the SI5351, and the 3,6k Resistor - but it made no difference.
Then I resoldered Pin 27+28 of the microcontroller - but this did not help either.

Also the question: Is there a difference between CW and SSB regarding the generation of the BFO signal?
I am not exactly sure anymore, but I think in CW the signal is so low that it is nearly undetectable - though the scope is able to detect a  frequency (picture)

However if i try to look at the signals at U3 when transmitting in CW it gets strange.

At 14.160 in CW I can see a 9,213 Mhz signal (the VFO I assume) at the output Pin4.  Should this not be already the mixed, final frequency?
(Pin 4 Picture 1 and Picture 2)

At Pin 6 the VFO is visible ( Picture 1 and Picture 2).  However I can nowhere detect the BFO Signal?
At Pin1 I also see see the VFO (sorry, no picture) and at Pin 5 the signal is too low to see anything useful.
Should not Pin 4 and 5 show the same signal, only in phase shift?

I tried to recreate the filter after U3 with LTSpice (never did something like this before). I I did it correctlya this would explain the low signal at Q2.
At 9,213 Mhz there seems to be an attenuation of about -30db (Picture).

Any ideas?