Re: Poor mans spectrum analyzer #ubitx

#61295

I don't know the circuit of the hackRF, but I wouldn't use any antenna connected to the SDR. You could fry its frontend unless it has some protection (I.e. Back to back diodes) at the antenna input. You just see a lot of overloading of your receiver. Having a 8bits ADC the dynamic range is similar to the RTL stick, 48db, so you need to attenuate a lot at least removing the antenna.

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Il 03/nov/2018 18:53, "Nigel G4ZAL" <nigel@...> ha scritto:

I have no sophisticated bench test gear so I used my hackRF and the free Spectrum Analyzer software to 'look' at what my uBitx was transmitting whilst on FT8 on 7.074MHz and the result is quite disappointing although not unexpected.
uBitx was on an EFHW for 40M and the hackRF was on a short whip antenna.

I have some Axicom relays and shielded SMD inductors for L5/7 and will compare results after swapping out the bits and see if I can 'clean up my act' !

Nigel

Re: the cause for the spurs, found!

#61294

Harmonics of the HP8640b are of the order of -50dB at output of the gen upto ~+10dbm..

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On Sat, Nov 3, 2018 at 09:43 PM, Henning Weddig wrote:

Glenn,

pleas keep in mind to check the output of Your signal generator, mostly the ahrmonics are in the same range i.e. about -30 dBc to the main cyarrier. So to make sure You do not make false measurements, place a low pass fitler between the output of Your sig gen and DUT.

Henning

Am 03.11.2018 um 10:33 schrieb Glenn:

Not much change really Raj, I used 39k.

At -10dBm input, there is a slight improvement by maybe 2-3dB

At -20 & -30dBm in, virtually same result.

I wonder if a notch could be added for the 2nd Harmonic..... Did you do any sums on the 3rd harmonic? It may also contribute.

glenn

Re: the cause for the spurs, found!

#61292

Great you found the likely cause of the 2IF spur.

Now why is the 45mhz IF distorting?

Two things, it needs to be clean to at least -6 or so DBM and how much gain is needed to
get to that from the ouput of the 45mhz crystal filter.

I'd suggest starting with transistors that actually have performance at 45mhz.

Allison

Re: the cause for the spurs, found!

#61291

As the saying goes two heads are better than one, good to hear it is finally cracked.

73 Steve

Re: Si5351 correction question

#61290

Should read:
"In the si5351bx routines as I wrote them, you simply adjust the value of si5351bx_vcoa"

That's how I do it in my own code.
But in the example code scrap of post 54501, I hacked it to use the indirect calibration offset,
since that's what everybody else seems to be doing here.
And managed to misspell "calibration:
< calibration = calibrtion + 10*enc_read();
> calibration = calibration + 10*enc_read();

Could be other minor bugs like that, but the method presented is correct.

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On Sat, Nov 3, 2018 at 12:01 PM, Jerry Gaffke wrote:

In the si5351bx routines as I wrote them, you simply the value of si5351bx_vcoa

Re: Ubitx Backup file .btx

#61289

开云体育

Yes , let us known where can we can find a download about default settings .

?

73 , Jens / HB9JOI

?

+++

?

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From: Daniel

Sent: Saturday, November 3, 2018 3:31 PM

To: [email protected]

Subject: [BITX20] Ubitx Backup file .btx

?

Hello everyone! Today I played a little with my Ubitx, I made a lot of contacts all over Europe. After a while I decided to listen myself on a SDR located somewhere in Norway because I wanted to play a little with the BFO. By accident I have sellected "Set Calibration" instead of "BFO" and everything was messed up, I couldn't hear or transmit nothing at all. I was lucky because I have a configuration file for backup and now I am back on the ionosphere. I am wondering, is there a website from where we can download this configuration file with the .btx extension? If someone else wants this file with the default settings, leave me a message. Thanks!

Re: Si5351 correction question

#61288

Somebody asking a non *Bitx* question here should give a full description
of what they have and they are doing.?
(This applies to those asking a *Bitx* question as well.)

And they should make sure it relates to *Bitx* products.
Some might consider this one borderline, but I think it's informative for *Bitx* users.

The original Raduino firmware for the Bitx40 used the Etherkit library.

Jerry

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On Sat, Nov 3, 2018 at 11:56 AM, Bill Cromwell wrote:

My comments were in a completely different universe :) I assumed being posted here it was something it is not. While we all know about "assume" it isn't unreasonavle to expect questions posted here to be about the Bitx machines. Moving on...

Re: Si5351 correction question

#61287

Vince says:
> crystal loading and the si5351 settings for the crystal. This caused the si5351 to be slightly off frequency.

This applies to pretty much all si5351 builds, so may actually be pertinent to the forum.

The 25mhz crystals typically available are tuned on the assumption that there will be maybe 18pF
of capacitance in parallel with the crystal.? (It's in the datasheet for your particular crystal.)
The si5351 allows you to program a parallel capacitance across the crystal of 6, 8 or 10pF.
There might be another pF or so due to traces, but we're typically well short of that 18pF
So our reference oscillator might be a khz above the expected 25mhz.
This is corrected by, wait for it ....? the correction factor.
As described in a previous post.

I did a quick check.
The Etherkit correction factor is in parts per billion, not in hz variance of the vco.
So Mark's change was 1.170 ppm, not 1170/875000000 * 1e6 = 1.337ppm
So his error was 12.5% less than I had previously calculated on the assumption
he was using the si5351bx routines.

In the si5351bx routines as I wrote them, you simply the value of si5351bx_vcoa
Farhan has added a level of indirection to this,
his correction factor get's added to the 875000000 default for si5351bx_vcoa.

Jerry, KE7ER

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On Sat, Nov 3, 2018 at 11:13 AM, Vince Vielhaber wrote:

I looked at your project and see you're using the adafruit si5351 board. There was an issue some time ago and recalling from a hazy memory it had something to do with crystal loading and the si5351 settings for the crystal. This caused the si5351 to be slightly off frequency. Jerry may remember more about it as I believe he addressed it in the si5351bx routines. I know it affected the Raduino, I'm just guessing the Adafruit is using the same or very similar crystal due to cost and availability.

Re: Si5351 correction question

#61286

Hi erry,

My comments were in a completely different universe :) I assumed being posted here it was something it is not. While we all know about "assume" it isn't unreasonavle to expect questions posted here to be about the Bitx machines. Moving on...

73,

Bill  KU8H

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On 11/03/2018 12:53 PM, Jerry Gaffke via Groups.Io wrote:
The etherkit library is totally different than the si5351bx routines
used on the uBitx.
So my discussion of the correction factor may or may not pertain.
Good luck.

On Sat, Nov 3, 2018 at 09:46 AM, Mark Pilant wrote:

    Hi Jerry.

        I have not heard of others in the forum voice concern about the
        si5351 calibration
        changing.

    I have not as well, but I wanted to check to see if my symptoms
    jogged anyone's
    memory. :-)

        Assuming your firmware is using the si5351bx routines that
        Farhan's original release
        was using,

    I'm not sure if it is; I haven't actually checked. The sketch I'm
    using to test
    the Si5351 is in the Etherkit (NT7S) GitHub repository.

    I might have to check out the 25 MHz oscillator. I have an HP
    Modulation Analyzer
    which should do the trick. (It also uses my GPSDO as a reference.) I
    do have an
    Efratom rubidium standard, but find my GPSDO (HP Z3816A & Spectracom
    8140) more
    convenient :-) :-)

    73

-- 
bark less - wag more

Re: Si5351 correction question

Vince Vielhaber

#61285

I looked at your project and see you're using the adafruit si5351 board. There was an issue some time ago and recalling from a hazy memory it had something to do with crystal loading and the si5351 settings for the crystal.  This caused the si5351 to be slightly off frequency.  Jerry may remember more about it as I believe he addressed it in the si5351bx routines.  I know it affected the Raduino, I'm just guessing the Adafruit is using the same or very similar crystal due to cost and availability.

Vince.

Show quoted text

On 11/03/2018 12:52 PM, Mark Pilant wrote:
Hi Bill.

When I replied with a suggestion he told me he is not using a Bitx40nor uBitx
nor a raduino nor any of the Bitx or uBitx software. -shrug-True at the moment.  I'm actually using a Mega2560 to control the Si5351
board with
a 3.5" TFT LCD interface.  The software is based on the VU2SPF and
VE1BWV sketch,
with the appropriate changes to run the display (which uses an HX8357D
chip).

I opted to use the simpler si5351 sketch to eliminate as many variables
as possible
to make sure the Si5351 board is operating as it should.

Here is a link to my work as of a couple of months ago:
    

I need to update it after picking it up again a week or two ago.  (Too
many irons
in the fire :-)

73

- Mark  N1VQW

-- 
  K8ZW     

Poor mans spectrum analyzer #ubitx

Nigel G4ZAL

#61284

I have no sophisticated bench test gear so I used my hackRF and the free Spectrum Analyzer software to 'look' at what my uBitx was transmitting whilst on FT8 on 7.074MHz and the result is quite disappointing although not unexpected.
uBitx was on an EFHW for 40M and the hackRF was on a short whip antenna.

I have some Axicom relays and shielded SMD inductors for L5/7 and will compare results after swapping out the bits and see if I can 'clean up my act' !

Nigel

spec_an1.jpg

Re: Si5351 correction question

#61283

The etherkit library is totally different than the si5351bx routines used on the uBitx.
So my discussion of the correction factor may or may not pertain.
Good luck.

Show quoted text

On Sat, Nov 3, 2018 at 09:46 AM, Mark Pilant wrote:

Hi Jerry.

I have not heard of others in the forum voice concern about the si5351 calibration
changing.
I have not as well, but I wanted to check to see if my symptoms jogged anyone's
memory. :-)

Assuming your firmware is using the si5351bx routines that Farhan's original release
was using,
I'm not sure if it is; I haven't actually checked. The sketch I'm using to test
the Si5351 is in the Etherkit (NT7S) GitHub repository.

I might have to check out the 25 MHz oscillator. I have an HP Modulation Analyzer
which should do the trick. (It also uses my GPSDO as a reference.) I do have an
Efratom rubidium standard, but find my GPSDO (HP Z3816A & Spectracom 8140) more
convenient :-) :-)

73

Re: Si5351 correction question

#61282

Hi Bill.

When I replied with a suggestion he told me he is not using a Bitx40 nor uBitx
nor a raduino nor any of the Bitx or uBitx software. -shrug-True at the moment.  I'm actually using a Mega2560 to control the Si5351 board with
a 3.5" TFT LCD interface.  The software is based on the VU2SPF and VE1BWV sketch,
with the appropriate changes to run the display (which uses an HX8357D chip).

I opted to use the simpler si5351 sketch to eliminate as many variables as possible
to make sure the Si5351 board is operating as it should.

Here is a link to my work as of a couple of months ago:
    

I need to update it after picking it up again a week or two ago.  (Too many irons
in the fire :-)

73

- Mark  N1VQW

Re: Si5351 correction question

#61281

Hi Jerry.

I have not heard of others in the forum voice concern about the si5351 calibration
changing.I have not as well, but I wanted to check to see if my symptoms jogged anyone's
memory. :-)

Assuming your firmware is using the si5351bx routines that Farhan's original release
was using,I'm not sure if it is; I haven't actually checked.  The sketch I'm using to test
the Si5351 is in the Etherkit (NT7S) GitHub repository.

I might have to check out the 25 MHz oscillator.  I have an HP Modulation Analyzer
which should do the trick.  (It also uses my GPSDO as a reference.)  I do have an
Efratom rubidium standard, but find my GPSDO (HP Z3816A & Spectracom 8140) more
convenient :-) :-)

73

- Mark  N1VQW

Re: Si5351 correction question

#61280

Hi Jerry,

When I replied with a suggestion he told me he is not using a Bitx40 nor uBitx nor a raduino nor any of the Bitx or uBitx software. -shrug-

73,

Bill  KU8H

-- 
bark less - wag more

Re: Si5351 correction question

#61279

I have not heard of others in the forum voice concern about the si5351 calibration changing.?

Unless you are using different firmware or there is an error in the firmware,
that sounds like the 25mhz crystal reference oscillator at the si5351 has changed a bit.

If you have a good second rig that can receive 25mhz, perhaps bring a short
antenna from it close to your uBitx and listen to the 25mhz oscillator, see if
you can hear it move, perhaps when blowing hot air on the si5351 board.

Assuming your firmware is using the si5351bx routines that Farhan's original release was using,
then the correction factor says how many hertz off from 875mhz the vco internal to the si5351 is.
The clock output frequencies and the rig operating? frequencies will be moved by a factor?
exactly proportional to to that correction factor, assuming your firmware is written correctly.
For example, you report two different correction factors of 15380 and 14210.
So in the first case, the vco was at 875.015380 hz, and in the second case at 875.014210 hz,
and the vco moved by 15380-14210 = 1170 hz, slightly more than a 1ppm difference.
That could be attributed to temperature or power supply differences around the si5351 and crystal.
A rig operating at 3.5mhz would have moved by? ?3.5mhz * (1170/875000000) = 4.68hz
If the rig was operating at 28mhz, it would have moved by 28mhz * (1170/875000000)?= 37.44 hz.?
Unless you are operating in one of the narrow band digital modes, those shifts are not of much consequence.
If you are operating in a narrow band digital mode in a varying temperature environment,
you may need a more stable reference than the 10 cent? 25mhz crystal supplied with your si5351 board.
There are si5351 boards out there with a TCXO (temperature compensated crystal oscillator)?
from QRPLabs and Etherkit.? ?The QRPLabs board can be GPS disciplined.
Or I suppose you could look into rubidium oscillators.? ?;-)?

I don't know if you are experiencing temperature or voltage changes around the si5351,
or exactly how much the frequency would shift if you did.
It could be that you have a more sensitive crystal than most, you might experiment with
swapping it out.? Better yet, get a different si5351 board.? Preferably one with a TCXO.

You might try cleaning the area around the si5351 and 25mhz crystal with alcohol.

Jerry, KE7ER

? ?

Show quoted text

On Sat, Nov 3, 2018 at 07:04 AM, Mark Pilant wrote:

My main puzzler is why, given the same Si5351 and Arduino boards, did the correction
number need to change to get the correct output frequency?

Ubitx Backup file .btx

#61278

Hello everyone! Today I played a little with my Ubitx, I made a lot of contacts all over Europe. After a while I decided to listen myself on a SDR located somewhere in Norway because I wanted to play a little with the BFO. By accident I have sellected "Set Calibration" instead of "BFO" and everything was messed up, I couldn't hear or transmit nothing at all. I was lucky because I have a configuration file for backup and now I am back on the ionosphere. I am wondering, is there a website from where we can download this configuration file with the .btx extension? If someone else wants this file with the default settings, leave me a message. Thanks!

Re: Si5351 correction question

#61277

Hi Mark.

What firmware are you running?None.  The calibration sketch is here:

This sketch simply programs the Si5351 as an oscillator, no USB, LSB, offset, etc.

Hi Jerry.

I'd recommend the algorithm of post   /g/BITX20/message/54501
( /g/BITX20/message/54501 ) for calibration.I'm eventually going to be doing something similar to what was mentioned in your
post.

My main puzzler is why, given the same Si5351 and Arduino boards, did the correction
number need to change to get the correct output frequency?

73

- Mark  N1VQW

Re: New file uploaded to [email protected]

#61276

Sorry for the above message. The audio is there its just very low. I should have checked
the info on the web site re this problem. and? Shall? have to get an amplifier to boost the audio
A Redface Regards
Fred Aunger (G6FJA)

Re: the cause for the spurs, found!

#61275

Correction:

After seeing your results I feel the stage is OK for upto -5 dbm ~~input~~ output where as the actual input
is -30 to -40 dbm. The output of the stage is max -10 dbm and so the input will be 15 -20dbm
less (i.e. gain of stage) So your Bidi amp is good to go.

At 03-11-18, you wrote:

Show quoted text

Raj
The input VSWR with that mod increased the input VSWR to around 7:1.? (measured 0-30MHz, my current setup)

I didn't check before the mod but assume its closer to 1:1.

glenn