Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
Evan -- so in this case, I am *using* the 10meter filter.? ? ?Its knee is at 32-ish MHz and appears to be used for 15 meters as well.? ? At least I hope I am!
These data seem to prove that we have at least a? -28dBc spur (harmonic) being formed due to the conduction of the output diode for the 10m filter!
There are likely OTHER sources, that are responsible for the remaining -34dBc 3rd harmonic.? ? ?Need to get all of this down below -43 dBc.? And for a radio of this advanced design, would be nice to have it significantly more impressive than just meeting requirements.? ?
The material I quoted cited "non linear passive components" -- is it possible that the capacitances of the reverse biased other diodes are also changing in a non-linear manner with instantaneous voltage (because the RF voltage is a varying percentage of the back biasing DC voltage) -- and that THIS is also changing the response in a non-linear manner and introducing harmonics?? ? Seems possible!? ? ?Ashhar wisely included a voltage doubler circuit, but that still means there is a significant percent change in the NET reverse bias on each part of a cycle.? ?What about either replacing the output diodes with RELAYS or using a much much higher reverse voltage?? ? ?
I just don't know exactly what next is the best step.? ? These diodes I don't think are ever switched "under load"? so a relatively modest relay could replace them.? ? at 40 watts, they should see currents only in the 1-2A range (even with 2:1 SWR).? ??
Anyone else made measurements on their V2?? ? Or have ideas?
Gordon KX4Z
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Re: An alternative for sBitx software development
I have trained myself to love vi. It is a single lightweight editor that is available on every platform from linux to android. It is has a little bit of learning curve of an hour, but you get used to it pretty quickly. - f
I found another advantage to running VS Code on my PC with a large monitor. I was working on my modified version of the sBitx code which wasn't working as well as the stock version. I opened file from the stock firmware in a window side by side with my version to compare them. I also cut and pasted some code from the stock version into my code.
--
73,
Mark, N8ME
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Re: uBitX v4.3 calibration
Not wrong at all. I used 10Mhz, per the instructions, but using the freq counter got me quite close. Thank you.?
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Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
Again, this unit was purchased from another person. I don’t think that person made any alterations, I can’t see any alterations and nothing looks burnt
I made up a small clip lead to try to short out the diets. This is certainly not optimal, because it will act like a small antenna. But it makes an easy way to allow me to sort out some diodes ?and see what happens
So using my UHF pad, and a bunch of BNC attenuators as well, on 21.02 MHz with Drive at 84% here were the values
fundamental: -6. ?Dbm
Second harmonic: -28 DBM
third harmonic -34 DBM
these are similar to some of my previous measurements for this band which is probably the worst
applying the shorting clips to the input Diode was no improvement and maybe one Db worse
applying the shorting clips to the output diode made a 6 dB improvement at the third harmonic
fundamental: -6 dBm
Second harmonic -29 DBm
third harmonic -40 DBM
I am out of time, so I can’t do much more, but I suspect these numbers would be better with a small short rather than this large clip. However it did not completely eliminate the problem. But it’s another clue. ?
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Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
Gordon,
The voltage doubler is applied to both input and output diodes.? Maybe the 10-meter filter is turning on enough to allow the harmonics through?? Just a guess.
All,
Has anyone else seen the harmonics issue with the V2?? Ashhar Farhan has stated that all V2 sbitx are tested with a spectrum analyzer for signal purity before shipment.
73
Evan
AC9TU
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Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
Yes, thanks, Bill and Evan.
The 1N4007 is certainly not specified or intended for PIN service ; it just happens to have an intrinsic layer. Not sure how thick, and it’s one very big reason I’m concerned that it might be the cause… but a lot of my other hypothesis of turned out to be incorrecr
i’m not so worried on the input side of the filter now that I’ve looked at the filter and I am amazed at how good they are, I’m much more worried about the outside of the filter!! ?I think this might be why I never ever worried really about the harmonics on the DE. As I remember all of my writing stay were about spurious submissions, and who knows some of those might have been due to the Cantenna!! Eventually I’ll go back and check it again but I had managed to get it much better.
I think once you select the band, the diodes stay in the correct settings? I’m not certain about that. But it wouldn’t be too terribly difficult to replace the output side diode’s with relays….. just would take more space!!
yes, I did the upgrade to give more current to the diodes—-BRFORE These measurements
if folks are going to use the one in 4007 and it turns out to be the issue, then careful selection is going to become necessary.?
gordon
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Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
Gordon,
The diode you listed in your post has a max reverse voltage of 50 volts.? That is 13 volts short of the 63 volts I calculate for 40 watts in a pure resistive 50-ohm load.? I have found that all pin diodes are hundreds or thousands of dollars for a minimum purchase required to replace the eight diodes.
Maybe go back to relays for LPF selection and change the program to keep the relays on for the selected band to allow for QSK CW operation?? I believe that you did this for your DE.
Another chain of diagnosis might be the voltage doubling circuit (as you pointed out in a prior post).? There may be an issue with the doubler voltage not being filtered enough, or the capacitor is on the high side of the ESR spec.
As I have stated before, I am NOT an RF engineer, just an industrial controls engineer tinkering with radio stuff.
73
Evan
AC9TU
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Re: sBitx Raspios Bookworm
Alsa is always there (it is the driver + userland support). Bookworm uses by default pipewire (on top of alsa), but you can just remove it if it causes trouble.
- Rafael
toggle quoted message
Show quoted text
On 10/20/23 14:21, Dave New, N8SBE wrote: Didn't Bookworm change the sound system?
Is alsa supported anymore?
73,
-- Dave, N8SBE
On 2023-10-20 07:15, Rafael Diniz wrote:
Hi Mark,
I never run RaspiOS Buster in the sBitx. I have being always with Bullseye 64 bit - all good. Should be the same with bookworm... there is nothing "special" in the sBitx software which makes is tied to any Linux distribution or version. Just take care of doing the proper alsa aloop setup and use the correct config.txt boot options.
- Rafael PU2UIT
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Re: sBitx Raspios Bookworm
Didn't Bookworm change the sound system?
Is alsa supported anymore?
73,
-- Dave, N8SBE
toggle quoted message
Show quoted text
On 2023-10-20 07:15, Rafael Diniz wrote: Hi Mark,
I never run RaspiOS Buster in the sBitx. I have being always with Bullseye 64 bit - all good. Should be the same with bookworm... there is nothing "special" in the sBitx software which makes is tied to any Linux distribution or version. Just take care of doing the proper alsa aloop setup and use the correct config.txt boot options.
- Rafael PU2UIT
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Re: sBitx Raspios Bookworm
You can just install it. I maintain a fork and packages of it for bullseye 64 bit.
Packages here:
But it compiles without problem if on different distro / version. Upstream also works:
- Rafael
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Show quoted text
On 10/20/23 14:10, Mark Erbaugh wrote: That's good information. Somehow, I got the impression that sBitx required Buster. It may have been something to do with the fact that WiringPi has been removed from the Bullseye repositories.
--
73,
Mark, N8ME
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Re: sBitx Raspios Bookworm
That's good information. Somehow, I got the impression that sBitx required Buster. It may have been something to do with the fact that WiringPi has been removed from the Bullseye repositories.
--
73,
Mark, N8ME
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Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
Gordon,
Did you try increasing the forward bias, as Ashhar Farhan has suggested?
73
Evan
AC9TU
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Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
I think you know this, but 1N4007’s are not PIN diodes… but we force them into that service and sometimes they work (just like forcing IRF510’s into RF service… something they were not technically designed for… but we do it).? They do not have exacting specifications for use as a PIN diode so your gut is probably right… wholesale replace them as they are cheap. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ?
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From: [email protected] < [email protected]> On Behalf Of Gordon Gibby Sent: Friday, October 20, 2023 4:26 AM To: [email protected]Subject: Re: [BITX20] sBitx V2 SN #141 Spurious/Harmonic Measurements ? After pondering this over night, I'm starting to more and more suspect that it has to be some diode that is AFTER the filters, since the filters look very impressive.
Even if you had a 3rd Harmonic EQUAL to the fundamental, those filters would push it almost 15 dB below the specification.? ? It is unbelievable that my 15meter 3rd harmonic of -28dBc is the result of anything BEFORE the filter.? ?Just unbelievable that it could be the drive, or final or anything!? ?Because a 60dB filter would wipe it out!
Also, in this post?/g/BITX20/message/105519? ?I showed proof that with some filtering AFTER the last diodes (an external filter) the harmonics can be? easily reduced to nearly undetectable (with a given spectrum analyzer setting).? ?This again validates my measurement setup.? ?If I can reduce the harmonics to undetectable....they don't seem to be the result of some failure of the measurement system shielding or linearity or anything else.
One of the most likely candidates for a diode past the filter is the 1N4007 used as a "PIN" diode at the output side of each filter.? ?These were not marketed as PIN diodes meeting any given harmonic suppression specification.? ?It could be possible that the intrinisic layer is of differing composition in different manufacturing outputs, and this might explain why some bands do well and others not in my particular Serial # 141.? ? And perhaps there are resonances or something in the circuitry?? ?
I found that PIN diodes are well known for producing harmonics.? ?There are IEEE papers on it that i can't get to because of a paywall.
I found specifications for high quality PIN diodes that guarantee 80 dB reduction in harmonics.??
I found a discussion on PIN diodes and their possibilities of making harmonics:?? "The primary intermodulation generator in a PIN switch is the forward biased series PIN diode. Intermod is generated in the diode when the stored charge becomes close to being swept out (or depleted) from the “I”layer region. Hence, low intermod switches employ diodes with longer than minimum minority carrier lifetimes and are biased at relatively high forward currents to store a log of charge in the junction. The degree of linearity is controlled by the percentage of charge depleted from the junction by the RF cycle. Highly linear switches have small percentage of charge depletion. See reference 3 for a more complete discussion of Intermodulation Distortion Mechanisms. A secondary intermod generator is the non-linear capacity vs. voltage characteristic of the reversed biased PIN diode. This phenomenon is relatively easily controlled by selecting diodes with flat capacitance vs. voltage characteristics and biasing the device into that region of the curve."
Unfortunately I'm leaving town in about 8 hours and have two classes to teach in between, so not sure I can get ANYTHING more done experimentally.? ?But what I think is the next thing to do is this:? ?On my 15 meter filter, which appears to be the most troublesome, use a bit of wire or a short jumper to SHORT OUT the output PIN (1n4007) diode, while the other three remain reverse biased -- and see if that changes the output spectrum.? ?I will have to reverse the soldering that I did to make the measurements of the filters before this can be done, but it may give some insight as to whether it is possible manufacturing variations in the 1N4007's are affecting the spectral purity of various serial numbers of the product.? ? I think it is the OUTPUT diode that is the most crucial.? ?If I am correct, then possibly some sort of test rig can be built to preselect the ones to use, or batches of diodes might be found to be good or bad.
All of this could be completely wrong, of course.? ?It might be something else.? ?I may have made another big mistake somewhere.? ?But more and more, I think I am validating my measurement technique and honing in on where the harmonics are coming from.? ?It should be fixable, since I was able to so clearly clean it up with a simple 2-section butterworth bandpass filter built for Field Day.?
73,
Gordon KX4Z
.? ?
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Re: sBitx Raspios Bookworm
Hi Mark,
I never run RaspiOS Buster in the sBitx. I have being always with Bullseye 64 bit - all good. Should be the same with bookworm... there is nothing "special" in the sBitx software which makes is tied to any Linux distribution or version. Just take care of doing the proper alsa aloop setup and use the correct config.txt boot options.
- Rafael PU2UIT
toggle quoted message
Show quoted text
On 10/19/23 01:10, Mark Erbaugh wrote: With the release of Raspios Bookworm, Raspios Bullseye has become the legacy release and Buster is no longer available for download from the Raspberry Pi website.
Will sBitx run with newer versions of Raspios?
--
73,
Mark, N8ME
|
Re: An alternative for sBitx software development
I found another advantage to running VS Code on my PC with a large monitor. I was working on my modified version of the sBitx code which wasn't working as well as the stock version. I opened file from the stock firmware in a window side by side with my version to compare them. I also cut and pasted some code from the stock version into my code.
--
73,
Mark, N8ME
|
Re: An alternative for sBitx software development
What editor do you use? I assume it is running on the RPi.
--
73,
Mark, N8ME
|
Re: sBitx V2 SN #141 Spurious/Harmonic Measurements
After pondering this over night, I'm starting to more and more suspect that it has to be some diode that is AFTER the filters, since the filters look very impressive. Even if you had a 3rd Harmonic EQUAL to the fundamental, those filters would push it almost 15 dB below the specification.? ? It is unbelievable that my 15meter 3rd harmonic of -28dBc is the result of anything BEFORE the filter.? ?Just unbelievable that it could be the drive, or final or anything!? ?Because a 60dB filter would wipe it out! Also, in this post? /g/BITX20/message/105519? ?I showed proof that with some filtering AFTER the last diodes (an external filter) the harmonics can be? easily reduced to nearly undetectable (with a given spectrum analyzer setting).? ?This again validates my measurement setup.? ?If I can reduce the harmonics to undetectable....they don't seem to be the result of some failure of the measurement system shielding or linearity or anything else. One of the most likely candidates for a diode past the filter is the 1N4007 used as a "PIN" diode at the output side of each filter.? ?These were not marketed as PIN diodes meeting any given harmonic suppression specification.? ?It could be possible that the intrinisic layer is of differing composition in different manufacturing outputs, and this might explain why some bands do well and others not in my particular Serial # 141.? ? And perhaps there are resonances or something in the circuitry?? ? I found that PIN diodes are well known for producing harmonics.? ?There are IEEE papers on it that i can't get to because of a paywall. I found specifications for high quality PIN diodes that guarantee 80 dB reduction in harmonics.?? I found a discussion on PIN diodes and their possibilities of making harmonics:?? https://www.quanticpmi.com/application-notes-how-to-specify-pin-diode-switches\
"The primary intermodulation generator in a PIN switch is the forward biased series PIN diode. Intermod is generated in the diode when the stored charge becomes close to being swept out (or depleted) from the “I”layer region. Hence, low intermod switches employ diodes with longer than minimum minority carrier lifetimes and are biased at relatively high forward currents to store a log of charge in the junction. The degree of linearity is controlled by the percentage of charge depleted from the junction by the RF cycle. Highly linear switches have small percentage of charge depletion. See reference 3 for a more complete discussion of Intermodulation Distortion Mechanisms.
A secondary intermod generator is the non-linear capacity vs. voltage characteristic of the reversed biased PIN diode. This phenomenon is relatively easily controlled by selecting diodes with flat capacitance vs. voltage characteristics and biasing the device into that region of the curve."
Unfortunately I'm leaving town in about 8 hours and have two classes to teach in between, so not sure I can get ANYTHING more done experimentally.? ?But what I think is the next thing to do is this:? ?On my 15 meter filter, which appears to be the most troublesome, use a bit of wire or a short jumper to SHORT OUT the output PIN (1n4007) diode, while the other three remain reverse biased -- and see if that changes the output spectrum.? ?I will have to reverse the soldering that I did to make the measurements of the filters before this can be done, but it may give some insight as to whether it is possible manufacturing variations in the 1N4007's are affecting the spectral purity of various serial numbers of the product.? ? I think it is the OUTPUT diode that is the most crucial.? ?If I am correct, then possibly some sort of test rig can be built to preselect the ones to use, or batches of diodes might be found to be good or bad.
All of this could be completely wrong, of course.? ?It might be something else.? ?I may have made another big mistake somewhere.? ?But more and more, I think I am validating my measurement technique and honing in on where the harmonics are coming from.? ?It should be fixable, since I was able to so clearly clean it up with a simple 2-section butterworth bandpass filter built for Field Day.?
73,
Gordon KX4Z
.? ?
?
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I just (09:50 CEST) tried out Gyula's download link: It worked seamlessly without any interruptions via a 100Mbit/s VDSL internet line by "Deutsche Telekom" and took approx. 7 minutes on an Android Smartphone. Download of a 2.7GB RAR-file with a 29.7GB image:  It does not seem like a problem on the hfsignals side. BTW: as far as I remember you should add ".img" to the file name, to be able to use the raspberry imaging tool.? -- 73, Joerg - DB2OO
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Re: Ship method from HF Signal
Hello Noel,
What Gerald has said is correct. We only ship through DHL as of now. We usually see the order being delivered to the US within 5 -7days and many times it has been delivered on the 3rd day from shipping.
Hope this helps.
Thomas
On Fri, 20 Oct 2023 at 01:58, noel ramos < noel@...> wrote: Hi!?
im thinking of purchasing one of the sBitX transceivers. I have a question: are they shipped by DHL or someone else and how long do they usually take to arrive in the East Coast of the USA.
TY!
Noel, W1NCR
--
Support@...
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Re: An alternative for sBitx software development
I do that my ssh-ing to the rpi. It doesn't work as well as the VS I guess but I open two sessions: one to edit and one to debug. - f
Visual Studio (VS) code has a Microsoft extension, Remote-SSH, that allows you to run VS Code on one computer and do the software development on another over SSH. This works with the Raspberry Pi (sBitx) as the remote computer. This allows you to run VS Code on a more powerful computer with a larger screen (without having to connect a HDMI display to the sBitx.
This creates an environment where I edit the code on my PC or Mac (where I have a 4K monitor), but still build and run it on the sBitx. Intellisense code highlighting and git version control work, including integration to my repo on GitHub.
--
73,
Mark, N8ME
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Labrador
Mark Erbaugh
K9HZ