Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
Thank you Evan. Can it lower the carrier peak and cause false increase of the spurs (vs the carrier)?
I'd be glad to find my measurements incorrect.
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73,
Wojtek SP5DAA
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Re: Fixed: cw latency and wsjtx/flidigi sidetone
Jody, others aren't reporting quite the same thing.? ? You are pointing to a delay in the T/R circuitry, and indeed there was one in the sBitx, as well as a sampling issue throughout.? ?However, it wasn't hard to fix BOTH in the sBitx.? ? I'm quite happy with the way that I ended up with my two SBITX's, running any speed of CW that I like, up to what I'm capable of (around 25 or so).? ? ?It wasn't that way AT ALL when we first started out with the sBitx line....but it is very nice with the way it is running with either my version or the 64-bit version being provided.??
I expect, before we are finished, that the zBitx will be the same!??
I can't get full break-in (between the elements of a single character) but I can get it to drop into receiver pretty much between every word (which is fine for me) and even more importantly?to me -- there are NO RELAYS CLATTERING.? ? I just can't stand relays doing that because I know they are going to quit and become flaky fairly early in life if I let them do that.? ? I had the same (or similar) level of break-in with my very FIRST radio as a ham, which was a Heathkit HW-16.? ? I know the Elecraft can do this, but for me, this was the first radio that was back to that level of CW performance..? ? The 7300 simply CANNOT match it in that regard.
73 Gordon KX4Z
On Wed, Apr 16, 2025 at 7:11?PM Jody - K3JZD via <k3jzd.jody= [email protected]> wrote: RE;? Why do some people have a problem with the zBITX CW Mode and others do not?
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I tested with a Straight Key.? ?I can offer the following observations and opinions:
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- Send Fast (20-25 WPM) and you will have no problems.? You will report that it works fine.
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- Send Slow (~10 WPM) and you will have lots of problems.? You will report that CW does not work.
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It appears that as long as you hold this Semi-QSK device in the Transmit Mode, all of your Dits and Dahs are going to be seen and transmitted.? Let it drop out of Transmit Mode for a millisecond, and there is too long of a delay before it will go back into Transmit Mode.? It is not an Input Polling problem.? It is a processing problem where going back into Transmit Mode and processing the key down event does not get immediate priority over everything else.? ?When sending CW, absolutely nothing else matters.? ?You will not be using the GUI - you will not using the Receiver - you don't need to adjust the Volume.? The key down event simply has to take priority over everything else in the zBITX software.? Period.
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I also observed that if you use the Macros to send CW (CQ, Exchange, etc), the sending speed is not important because the Macro processing function holds the device in the Transmit Mode until the macro has completed.? So 5 WPM CW works fine here.
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I'm sure that there are some other extenuating circumstances, like the time that the CPU spends on all of the other totally unnecessary desktop OS crap that is running on this embedded RasPi device (like do we really need Bluetooth to be turned on?).? But I would not be too quick to blame all of that stuff without a detailed histogram showing where the zBITX RasPi is spending its time.
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As far back as I can remember, the *bitx family of radios has never had a very good reputation with running CW Mode.? Maybe that can be overcome with this zBITX.
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72,
Jody - K3JZD
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Re: Fixed: cw latency and wsjtx/flidigi sidetone
RE;? Why do some people have a problem with the zBITX CW Mode and others do not?
?
I tested with a Straight Key.? ?I can offer the following observations and opinions:
?
- Send Fast (20-25 WPM) and you will have no problems.? You will report that it works fine.
?
- Send Slow (~10 WPM) and you will have lots of problems.? You will report that CW does not work.
?
It appears that as long as you hold this Semi-QSK device in the Transmit Mode, all of your Dits and Dahs are going to be seen and transmitted.? Let it drop out of Transmit Mode for a millisecond, and there is too long of a delay before it will go back into Transmit Mode.? It is not an Input Polling problem.? It is a processing problem where going back into Transmit Mode and processing the key down event does not get immediate priority over everything else.? ?When sending CW, absolutely nothing else matters.? ?You will not be using the GUI - you will not using the Receiver - you don't need to adjust the Volume.? The key down event simply has to take priority over everything else in the zBITX software.? Period.
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I also observed that if you use the Macros to send CW (CQ, Exchange, etc), the sending speed is not important because the Macro processing function holds the device in the Transmit Mode until the macro has completed.? So 5 WPM CW works fine here.
?
I'm sure that there are some other extenuating circumstances, like the time that the CPU spends on all of the other totally unnecessary desktop OS crap that is running on this embedded RasPi device (like do we really need Bluetooth to be turned on?).? But I would not be too quick to blame all of that stuff without a detailed histogram showing where the zBITX RasPi is spending its time.
?
As far back as I can remember, the *bitx family of radios has never had a very good reputation with running CW Mode.? Maybe that can be overcome with this zBITX.
?
72,
Jody - K3JZD
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AmateurRadioKits AGC Connection to uBitx v6
I am not getting good results with the AGC supplied by AmateruRarioKits.? I am unsure if it is a bad board (it does not have the multi-turn potentiometers shown in the documentation) or if it is the connection point to the uBitx board.
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The photo shows the connection to the collector of Q10.?
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The instructions show connecting to the base across R10:
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I will try moving the connection and see if the performance improves.
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Has anyone else installed this board successfully and is happy with the results?
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73
Evan
AC9TU
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
Wojtek,
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From the TinySA Ultra wiki:
- For best measurements keep input power below -25dBm
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I always ensure that the peak displayed is below -25dBm.? With either my Basic or Ultra, I get different results if I go above that value.
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My setup uses a 40dB 25¡ªor 100-watt attenuator followed by a 2-watt-rated step attenuator to dial in the best signal level for the measurement.
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73
Evan
AC9TU
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
So one hypothesis is that HFSignals got a bad batch of ms5351's, where some of them perform below spec in terms of clock crosstalk. ?But some (Ashhar's) are Ok.
If this turns out to be the situation, how hard is it to rework/replace this IC?
Ron
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
A man with a watch knows what time it is, a man with two watches is never sure...
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@VE6LK @HRWB
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--
Regards,
Dave, N1AI
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
I have tested my zBitx in CW mode with DRIVE=100 with 50 Ohm 40 dB attenuator and tinySA, on all bands.
Sorry, I took the pictures with a mobile, so the quality is poor.
Below are the results.
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10 m:
12 m:
15 m:
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17 m:
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20 m:
30 m:
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40 m:
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60 m:
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80 m:
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So it looks like the spurs are not always 40 dBc below the carrier...
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73,
Wojtek SP5DAA
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
Oddly enough, I don't show this using the zBitx on 40m with the tinySA Ultra, same span. This is the first good thing I'm able to report about this radio.
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Re: zBitx touchsreen issue
Sam, Wolfgang,
I would lift off the front panel (un-snugging the four screws might be enough) to see if it relieves pressure on the screen itself and try again. When I tried with mine it sat forever until I touched it, ie. no time-out was apparent.
72,
.Vince
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
So what is different about Ashhar¡¯s ?unit, since he¡¯s not seeing it? Different manufacturer of the chip? Different bypassing? Different loading?
toggle quoted message
Show quoted text
On Apr 16, 2025, at 13:41, Ron, N6YWU via groups.io <ron.nicholson@...> wrote:
? If intermodulation is between the 40 MHz clock and transmit clock, a quick test might be to turn off Si5351 clk1 during transmit (re-insert 40 MHz farther down the signal chain from an external clock generator source, if needed), and see if the intermodulation artifacts go away.
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Ron, n6ywu
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
If intermodulation is between the 40 MHz clock and transmit clock, a quick test might be to turn off Si5351 clk1 during transmit (re-insert 40 MHz farther down the signal chain from an external clock generator source, if needed), and see if the intermodulation artifacts go away.
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Ron, n6ywu
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
I did some additional measurements and I am now pretty sure, that the root cause for the spurs is intermodulation between the 40MHz IF signal @ CLK1 and harmonics of the transmit oscillator signal @CLK2.
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Measurement @ 10.1MHz:
Spurs are +/- 400kHz around 10.1MHz: 40MHz +/- 4*10.1MHz = +/- 400Khz
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Measurement @ 10.2MHz:
Spurs are +/- 800kHz around 10.2MHz: 40MHz +/- 4*10.2MHz = +/- 800Khz
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Measurement @ 7.0MHz
Main Spurs are +/- 2MHz around 7.0MHz: 40MHz +/- 6*7.0MHz = +/- 2Mhz
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Main Spurs are +/- 3.2MHz around 7.2MHz: 40MHz +/- 6*7.2MHz = +/- 3.2Mhz
The Spur #6 is @ 3.2MHz = 6*7.2MHz-40MHz
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Measurement @ 18.1MHz
Main Spurs are +/- 3.8MHz around 18.1MHz: 40MHz +/- 2*18.1MHz = +/- 3.8Mhz
and they are really bad: only 20dB below the carrier!
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...and so on and so forth...
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The initial impression, that there are spurs +/- 2.x MHz? were a result of the measurements at 7.y and 14.z MHz with intermodulation products in the 2.xMHz range.
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73, Joerg - DB2OO
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
I have yet measured the output voltage (after the 40 dB attenuator). Below are the results. Indeed, one can see a 2 MHz amplitude modulation.  That's not an aliasing artifact. Below there is a picture with another time scale. Yet another picture, taken from the battery connectors (with AC coupling of course)  So I don't see any 2 MHz component there, that could justify the AM modulation caused by the batteries resistance and varying current consumption. A? 14 MHz components is clearly visible.
73, Wojtek? ?r., 16 kwi 2025, 18:29 u?ytkownik Joerg DB2OO via <db2oo.ju= [email protected]> napisa?: Frank,
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my measurement setup has been described already in my FIRST posting on this topic:
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" Measurement with a TinySA Ultra connected via 50dB (20dB + 30dB) attenuators.
Adding another 30dB of attenuation does not make a difference in the measurement result: The TinySA will then keep its internal attenuator at 0dB, but the spurs will still be -28dBc.
Reducing Drive to 50 will reduce the spurs to -31dBc."
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BTW: using a TinySA instead of a TinySA Ultra provides exactly the same results.
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I have built at least a dozen transceivers over the last years: none showed this kind of spurs.
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To eliminate the voltage regulators U6 and U7 as the origin of the spurs, I added the missing 22uF tantalum capacitors on their outputs --> no difference, spurs are still there.
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BTW:?the solution is not "shoot the messenger".
--
73, Joerg - DB2OO
Wojciech M. Zabo?otny
My GPG/PGP keys:
standard: 8192R/7E17F00A (B53C 1F09 BEA9 ED46 51B6 ?2C2E 4344 F292 7E17 F00A)
confidential: 16384R/1FEDB03C (3412 2330 E225 D57D 70C3 ?2340 B294 9408 1FED B03C)
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Re: zBitx touchsreen issue
The calibration?screen does come up - for less than 2 seconds.
Not enough time to calibrate.
What next?
Same issue as Sam. Pressing the screen while powering up and releasing shows the calibration screen with red markers in every corner. One corner has a white marker, touching it shifts the marker to the next corner but now the process stops and booting continues. I did not manage to touch all four corners. But all functions of the Zbitx? work when? using the web interface or keyboard, mouse and HDMI. Another issue was the delivered Micro-USB-Adapter. Now another adapter and a simple USB-Hub do the job. I have the same software as Sam and also updated Zbitx and display, but no help.
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73, Wolfgang, DH2WS
rev 1.06 / 3.052
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
I don't know where R70 is on the PCB, or how accessible it might be. ?
Can Ashhar have someone back at the factory swap out R70 with a clock buffer and see if that reduces spurs?
- Ron
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
Frank,
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my measurement setup has been described already in my FIRST posting on this topic:
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" Measurement with a TinySA Ultra connected via 50dB (20dB + 30dB) attenuators.
Adding another 30dB of attenuation does not make a difference in the measurement result: The TinySA will then keep its internal attenuator at 0dB, but the spurs will still be -28dBc.
Reducing Drive to 50 will reduce the spurs to -31dBc."
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BTW: using a TinySA instead of a TinySA Ultra provides exactly the same results.
?
I have built at least a dozen transceivers over the last years: none showed this kind of spurs.
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To eliminate the voltage regulators U6 and U7 as the origin of the spurs, I added the missing 22uF tantalum capacitors on their outputs --> no difference, spurs are still there.
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BTW:?the solution is not "shoot the messenger".
--
73, Joerg - DB2OO
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
The U.S. regulation is -43 dBc. ?The spur 2.5 MHz above the carrier does not get close enough to meeting that spec for me to be interested in taking more careful measurements. ?I can also hear that spur from an antenna above my roof. ?That's a reasonably large air gap.
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Also: Production units may vary. ?Have you done any statistical QA across multiple units to measure the variance? ?Maybe my unit is a statistical outlier. ?
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But more than one person has reported these spurs, all using different test setups. ?What are the odd that all these different setups are producing the same measurement error?
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73, Ron, n6ywu
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Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
Work, The spurs are well below -40 dbc
My zBitx arrived today. I can confirm that when working from batteries, it produces those modulation (?) components.  
73, Wojtek SP5DAA? ?r., 16 kwi 2025, 17:36 u?ytkownik Joerg DB2OO via <db2oo.ju= [email protected]> napisa?: To be on the safe side, I tested it with a lab supply as well as with 18650 batteries:
Same result, the +/- 2.x MHz spurs are there with both types of power supplies!
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I think the spurs are originating in the SI5351/MS5351, which has to deliver much more power than in the sBitx, which has low oscillator power demand, due to buffer amplifier for the 40MHz and high impedance input of the KISS-Mixer.
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The only band, where I did not see them is 80m, where the output seems to be clean.?
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On Wed, Apr 16, 2025 at 10:00 AM, < Vu3vwr@...> wrote:
Joerg,
Are you running the tests with batteries or are you using an SMPS to power the radio during the test? 2MHz is a common switching frequency and as Wojtek suggests, the issue maybe the PS.
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I have raised this with Farhan and will wait for him to chime in on this after he has a look.?
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73,
Ragav
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73, Joerg - DB2OO
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Re: zBitx touchsreen issue
Same issue as Sam. Pressing the screen while powering up and releasing shows the calibration screen with red markers in every corner. One corner has a white marker, touching it shifts the marker to the next corner but now the process stops and booting continues. I did not manage to touch all four corners. But all functions of the Zbitx? work when? using the web interface or keyboard, mouse and HDMI. Another issue was the delivered Micro-USB-Adapter. Now another adapter and a simple USB-Hub do the job. I have the same software as Sam and also updated Zbitx and display, but no help.
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73, Wolfgang, DH2WS
rev 1.06 / 3.052
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Dave, N1AI
Sam Hanie
Wolfgang