Re: S/N 0994 receiver internal noise
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Re: S/N 0994 receiver internal noise
On Sat, Jan 4, 2025 at 12:11 AM, w9blw wrote:
big question is how is the noise. ill put it this way, if the radio performed as it is now i would had never thought there was an issue.? do i still see things when i crank the IF past 90 yes.. but it doesn't look abnormal, no birdies or hard hash in one spot. Ill be the first to admit the radio is a ton of fun with or without this shielding but it has seemed to make a difference and its a fun project.?
Thank you for introducing your work and for these words you wrote here:
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Gyula HA3HZ
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Re: sbitx v3 circuit and performance details
ps,: reverse voltage when it reaches and exceeds the set current the reverse bias: it does not reverse the voltage, but reduces it to the extent that the current consumption exceeds it.
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Gyula HA3HZ
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Re: sbitx v3 circuit and performance details
Gordon,
I don't have a Zener or suppressor on the gates of the FETs. I think about this differently and only limit the input power for protection.
My power supply is a current limiting and has a reverse voltage when it reaches and exceeds the set current.
I had to change FETs when I wasn't using it for broadcasting, because I didn't have an antenna, but it was powered by a battery and I only used it for monitoring (there was no current limitation). I don't remember the details, maybe it was on a dummy load in a setting.
That's why I mentioned that the sbitx is a male egg that needs to be taken care of. I made another modification around the power stage, which is more complicated. I did it because I couldn't do the Bias setting correctly.
The current consumption always jumped even with a small adjustment of the potentiometer.
That's why I built Didier's circuit control of the F5NPV.
The FETs are not connected to ground directly, but through an RC element (0.2 Ohm parallel 220n).
Also, the Bias voltage is temperature dependent, controlled by 6 diodes connected in series.
Yes, this is not easy to replicate, which is why I deleted my previous comment. I am currently using the device this way.
I bought 10 of the FETs and selected them with a transistor meter for the closest opening voltage, which I installed.
It worked for me. Everyone should decide for themselves how to use the device.
My suggestion of AlN (aluminum nitride) for installation was only made after the thermal photographs appeared.
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Gyula HA3HZ
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Re: sbitx v3 circuit and performance details
On Mon, Nov 20, 2023 at 06:45 PM, ajparent1/kb1gmx wrote:
Gordon,
That is true...? save for there is a transformer between the transmission line and the Drains.
If its 1:4 (impedance) step up going out it will work the opposite ways for the return
signal for a total return loss.? So the voltage is 1/2. (sqrt(4)).? Its greater for a
1:9 (1:3 turns) case.
Still I've used 3x to 4x as a safety margin.? The 100V irf510 is fairly resistant at 24V
and less so at 32.? For nominal 12V (13.8V DC) that means 55-60V device has
enough voltage margin.
However blowing devices is often a symptom of other things going on such
as RF instability or DC instability.
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Allison
Puzzled still how I blew an IRFZ24N (just one -- the other appeared fine) in a highly modified V2 which has huge zeners across the gates to ground which have been shown with oscilloscope photos to literally protect the gates.? ? The drive level was 68% (and 100% had been set to move about 35 watts into 50 ohms) but the device was through an un-tuned autotuner, into the input circuitry (which has a tuned circuit) of an ancient Heathkit SB-200 amplifier.? Frequency around 3.550 MHz.? ?I had forgotten to hit the "tune" button on the autotuner between the sBitx and the amplifier.? ?After only a few dits and dashes -- shorted PA Mosfet, with current limiting by the power supply and huge current indicated on an external current meter.
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I'm guessing I created a situation that resulted in either damaging voltage or current on the 55V IRFZ24N device.? ?Voltage might be more suspect?? ?The MOSFETS were heatsinked using Aluminum nitride pads with goo, and had ben installed a year or more previously and no problems ever since until this moment.? ?
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Definitely a learning moment for me.? ?This is the FIRST MOSFET in a PA that I've ever had go south.? ?I don't operate hours and hours like others here; I'm more of a tinkerer who just puts things together, makes a few contacts, does some winlink and spends an hour or more just listening to relatively high speed CW in the early morning for practice.? ? But I've spent many hours and hours diagnosing problems with various units.? ?Maybe the IRF510 is indeed tougher due to its higher drain voltage rating?? Dunno.
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Gordon KX4Z
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Re: zBitx orders are closed
Wonderful problem.? ?How many orders did you take before you stopped?? I am one of the lucky ones waiting anxiously for my delivery.?
Doug, KI6DS?
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Re: zBitx orders are closed
Greetings Farhan !
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Awesome - Can't wait !
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Maybe start a list where we can register interest for next round of orders !
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73s
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Re: S/N 0994 receiver internal noise
Wb9blw. ?
Looking good! ?I also had the problem with the speaker. ?I made a low profile shield from .030 thick lexan sheet and covered it with copper tape. ?It is secured with 2 of the board of mounting screws and has a bonding ground to the case next to the pi. The shield continues under the pi. ?Picture attached. ?I will add the aluminum shield on top of this. ?
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Re: BlueDV on sBitx is now available
JJ, Can it be used with the standard setup file for BlueDV? I have a ThumbDV on a Raspberry Pi, with Ambiserver and a port-forwarded hole through my firewall. I use BlueDV for Windows in the house, and BlueDV AMBE for Android to connect to it with my phone from anywhere else. Can the version you've made accessible to an sBitX also have the Ambeserver options in the setup file? Because if so, that's really huge for me!
-=-=-=-=-=-=-=-=- 73, Gwen, NG3P
I created a software installation package for BlueDV on the sBitx. If you already have the ELF image installed, then it is fairly easy to install with my script.
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For more information, please see the forum post at ?
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-JJ
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Re: S/N 0994 receiver internal noise
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Ryan, I mocked up some forms to act as a mold for shielding tape yesterday.? The output side had plenty of space to add a full shield and seems like a no brainer. The input side did not have any room to spair so i had to cut the middel part of the form out. The speaker literally touches some of the coils. I was able to add some shielding to the sides but i don't know if its really attributing to anything.? i added the .stl files i used to this post if anyone wanted to try this them selves, as a disclaimer I am self taught with 3d design so I'm sure someone could do much better. you will need to print them on their back and use an auto tree for the over hangs.? They print really nice, i use a bambu P1S. i printed 100% fill and they still print fast (~1 hour) with a .06 hotend . as you can see you will need to cut away at them depending on how you want them to fit but that is very easy to do.? big question is how is the noise. ill put it this way, if the radio performed as it is now i would had never thought there was an issue.? do i still see things when i crank the IF past 90 yes.. but it doesn't look abnormal, no birdies or hard hash in one spot. Ill be the first to admit the radio is a ton of fun with or without this shielding but it has seemed to make a difference and its a fun project.? some photos with notes.?  ?
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Re: S/N 0994 receiver internal noise
Ryan, I mocked up some forms to act as a mold for shielding tape yesterday.? The output side had plenty of space to add a full shield and seems like a no brainer. The input side did not have any room to spair so i had to cut the middel part of the form out. The speaker literally touches some of the coils. I was able to add some shielding to the sides but i don't know if its really attributing to anything.? i added the .stl files i used to this post if anyone wanted to try this them selves, as a disclaimer I am self taught with 3d design so I'm sure someone could do much better. you will need to print them on their back and use an auto tree for the over hangs.? They print really nice, i use a bambu P1S. i printed 100% fill and they still print fast (~1 hour) with a .06 hotend . as you can see you will need to cut away at them depending on how you want them to fit but that is very easy to do.? big question is how is the noise. ill put it this way, if the radio performed as it is now i would had never thought there was an issue.? do i still see things when i crank the IF past 90 yes.. but it doesn't look abnormal, no birdies or hard hash in one spot. Ill be the first to admit the radio is a ton of fun with or without this shielding but it has seemed to make a difference and its a fun project.? some photos with notes.?  ?
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Re: I need to regain control of the Raduino in my uBITX V6.1
Hi Peter, Happy New Year!
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Have you viewed the calibration video by Ashhar Farhan?
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Note that you need to hold the tuning knob (encoder) for up to 15 seconds for the calibration screen to come up.? Ashhar Farhan does this at around 4:15 in the video.
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Also, note that the BFO tuning page no longer works.? Any audio spectrum analyzer can be used to measure audio amplitude by frequency between 300 and 3,000 Hz.? Here is a PC-based software:
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It may be that your encoder is faulty if you can not get to the settings page.? There could be a wiring issue between the encoder and the Raduino board.??
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You can also try reloading the firmware to the Nano on the Raduino board.? There is another video that demonstrates that here:
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73
Evan
AC9TU
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I need to regain control of the Raduino in my uBITX V6.1
A Good New Year to one and all.
I have a ?BITX V6.1 which is giving me a severe headache, and I need to regain control of the Raduino inside.
Several times I have essayed to run the calibration routines, the last time was interrupted by unusual circumstances, and it has taken a long time to come back to working on the transceiver. Which is still causing me a severe headache!
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The situation is this:-
The receiver seems to be functioning, though it hasn’t been able to reproduce any signals yet.
The problem seems to lie with the Raduino- the display shows the expected layout of square fields to select modes and the various bands; I can swop between VFO’s A and B; the numbers in these boxes can be changed or tuned; the expected text is shown at the bottom of the display, etc.
The tuning ranges I can achieve are initially confusing, rotating the knob clockwise takes the numbers higher and higher, but rotating anticlockwise they go down to a certain point in the MW band, and then increase again. It seems that the calibration is way, way off. Which also seems to apply to the BFO injection.
While rotating the tuning knob and with a short antenna attached, I can hear that the RX tunes through some very high pitched signals, they shriek. These disappear when I disconnect the antenna.?
I surmise I need to run both the calibration routines again and to complete them properly this time.
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BUT how can I start to do this? Pressing the Tune knob does NOT allow entry into the setting up routines, it doesn’t do very much at all except that every 4 or 5 presses it will go to the Fast Tuning mode, And out again after 2-4 presses.?? Strange as it must have worked before!
I cannot enter into the Set-Up functions or any other modes at all.
Repeated power cycling, with a 10-20sec wait has not made any difference. Each time the Raduino reboots and starts up with a white screen then blue and then the normal ops screen.
Nor has pressing the reset button on the Arduino module had any other effect, just the same restart.
This was a little challenging, I made up a special tool of wood, to reach into the space above the Arduino while it was still in place, and with a crank to accommodate the alignment, or lack thereof, getting past the left hand wall of the case. And yes, I am certain I got a reaction to pressing the reset button, which was the same reaction as from a power cycle.
I will borrow a frequency counter to see if the various oscillator frequencies can be ascertained, and I suppose I should check the voltages around the Arduino again. And I’ll try to fit a switch in parallel to the reset of the Arduino.
Note that the unit has been tried with 3 different PSU’s all around 12-13.5V out across the months.
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Can some of you gentlemen help me with suggestions and advice as how to regain control of the Raduino. I would also like to point out I am not well versed in playing with these small processer modules and will need guiding instructions to figuratively ‘hack it’ open.
My experience with advanced computer control only reached to serial RS232 and sometimes RS422 communication and I have trawled through the Groups list but have not found any references there that were relevant to this situation as I perceive it.
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I wonder if I should also ask if these Arduino’s or Raduino boards are still available to purchase?
Peter LB0K
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BlueDV on sBitx is now available
I created a software installation package for BlueDV on the sBitx. If you already have the ELF image installed, then it is fairly easy to install with my script.
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For more information, please see the forum post at ?
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-JJ
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Have you got a update to this new unit . also would you be willing to make the filters for 2m also?? I like the work you have done but you dont have the making for the filter boards and what you used for a amp... I am looking to get a 6m setup if you have them or the updated gerber and a case you use ...
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Re: S/N 0994 receiver internal noise
Thanks for the photos.? ?Documentation of exactly what physical techniques are used will help others.? ?
Gordon?
On Thu, Jan 2, 2025 at 10:51?AM Ryan Wesolowski via <cosmo1stgen= [email protected]> wrote: I have begun working to shield mine.? We will see if it was worth it.
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Ryan
KK6DZB
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Re: S/N 0994 receiver internal noise
I have begun working to shield mine. ?We will see if it was worth it.
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Ryan
KK6DZB
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OK,, so I implemented the changes, changing the 20msec delay to 5msec, and the 10 msec delay to 5 msec
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Again, I don't have a working power amplifier stage right now, so can't test fully.? ?However
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a)? it seems to work fine in testing on 80 meter CW , watching the first "dit" it seems only slightly shortened at 25 wpm as expected.? ?
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b)? I set up the ancient SB-102 on the same frequency and it can just barely hear the DRIVER stages of the sBitx
Listening to the signal there, when I send "i" to start off a transmission.? ? (2 dots)?
The first dot is only a tiny bit shorter than the second -- they would be easily recognized as an "i" by human listeners.
This was done with external keyers, sending their output as "straight key" to the input.? ?Both keyers that I'm able to test here, continued to sound perfectly normal.? ?
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I still don't have real power, so I can't tell what would happen in the way of "clicks and thumps" but I found that with about 200 mSec of delay, I had fairly nice "breakin" conditions at about 25 wpm, able to hear between letters (which is about all I would want).? ?It has been YEARS since I had full break-in (heathkit hw -16) so I don't really remember operating with it.? ?Normally these days I just settle for semi-breakin (of course when using a linear that has no QSK, only a relay)? ??
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So this is MORE than the improvements I was going to try to accomplish during this vacation trip back to North Carolina -- mostly thanks to Mike!? ?Huge improvement so far.? ?When a new MOSFET arrives, I can try it with more power.? ? Guess I might have to replace both to try and keep similar bias currents, if I can't do that with the primitive tools I have here, just take the radio back home and repair.? ?I have a 2nd radio waiting for me back there to upgrade, anyway.
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Once again, I have submitted to the West Central Florida TECHCON (2025) conference a talk on the progress of the sBitx/now zBitx as well.
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73
Gordon KX4Z
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Mike, thank you for commenting on much of the development and filling me in, on which code has what improvements, etc .? ?I wish I had the energy and time to learn the github stuff....but haven't yet.? ?Can only hope that the people who are working there READ the work that others are doing....such is life.
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OK, I have tried to analyze the hardware absolute limitations that should be covered by the software delays in order to maintain the operation that Ashhar set up for going from receive to transmit without damage.? ?My full analysis is attached.
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Basically
1.? ?In order to have less than 25% degradation of initial dot, @ about 25 wpm we need to get the turnon delay down to about 15 ms or less.??
2.? ?I don't know about the time requried to turn of channels in the codec, and the delays he put in are minimal, so leave alone.
3.? ?Driving the TX line high causes power to be applied to several lower power systems, and also to the PA bias circuitry, which might be the slowest part of the entire thing, and had a time constant of approx 0.5 millisecond.? ?I did some calculations to estimate the time to turn on Q23 fully, and it is down in the microseconds, so that doesn't seem to be a problem.? ?Providing 5 milliseconds here should be sufficient.
4.? ?Re- setting the Low Pass filters requires discharging as much as 6000 pf through the high voltage Mosfets, but they have an on resistance of about 5 ohms, so the time constant for that is in the tens of microseconds -- so again we don't need much time, maybe 5 milliseconds more.
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With all that we should be able to ahve a turn on set of delays that add up to about 13 milliseconds, and that would be a very nice turn on.
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I can't TEST it properly until I get a replacement IRFZ24N installed -- I don't have any with me at the vacation home because never anticipated this damage.? ?Some are coming from Amazon on Saturday just before we leave to drive back to Gainesville FL.? ?However, I can try the code just to see if anything happens with no real output power, later today.? ??
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With these two fixes combined, I think it will be a HUGE improvement for CW ops up to about 30wpm which is the vast majority.? ?And so far implemented in the 32 bit code, but the same ideas should work in the 64 bit code that I examined.? ?I have all kinds of special stuff in my code so not sure I want to completely switch over just yet.? ?
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Gordon KX4Z
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On Thu, Jan 2, 2025 at 12:07 AM, Gordon Gibby KX4Z wrote: 1.? No I have NOT been following anything at all about the 64-bit version
because I have too many other responsibilities etc.? ?This Christmas break
was the first chance I had to take a look at the CW responsiveness
improvements. 2.? I have previously provided some code to avoid unnecessary clattering of
relays in the DE version (but since I don't do GITHUB, that wheel gets
reinvented over and over and hopefully finally implemented in the github
versions. Looking at the LPF relay noise was was got me into looking at sbitx source! You posted the solution, and I manually edited it into my machine over and over again. It is still an 'issue' on the 32 bit baseline, though the recommended changes have been part of the 64 bit baseline for some time. 3.? Here is where I found what MIGHT be the sbitx.c in the 64-bit version:
I note that it is still using all the same (20 msec, 10 msec) delays as the
original 32-bit code, in the transition from receive to transmit. You did indeed find the latest version of sbitx.c in the main branch of th 64 bit repository. That is the last version released. You can probably see that it does include the fixes you found a long time ago to correct the relay chatter. There are other branches from main that contain fixes like the CW timing changes you've just looked at, and my simplified (?) tr_switch(). At some point those might get pulled into 'main' and be part of next reelease - I can't say. 4.? You had indicated you have basically removed ALL the delays, did I
understand that correctly???? ? The code doesn't give engineering
explanations of why the delays were instituted so I'm concerned about all of
this.? ?I think our goal might be to reduce the delays (which you measured
at about 30 msec I believe) to 12-15 mSec so that a "dot" at 25 wpm isn't
shortened more than about 25% Well. Concern is good! But, the 32 bit baseline today still has code for tr_switch_de and tr_switch_v2. But the tr_switch_de may be dead code, unreachable (try inserting a print statement in tr_switch_de and tr_switch_v2 on your DE machine, and see which code gets run). Now that's not a big deal because people like you made the fix on the local baseline. And it gave me some confidence to think, hey, most sbitx users are just running the tr_switch_v2() so it might be very possible to just have one tr_switch and drop the DE code! So I do that. At one point Farhan sent a short note (somewhere here) explaining that that the electronic T/R switch controlled power to the PA, and an RC element provided timing, so I got a liittle relief (on my own concern!) that hardware was going to look out for me a little. De-energizing all the LPF relays, re-configuring them for band of operation, just seems unnecessary at the level of break in keying. I think the original plan was probably just do it when you do it at band change, but someone liked the idea (I know, that's engineering judgement) of opening the LPF switches to try to reduce ringing? Risk. What can I say - it works for me on my DE machine. I can claim a small benefit. A handful of testers have run my simplified tr_switch while testing the CW timing fixes and no problems reported. Take a look at the code and let me know what you think! It's been a while since I walked through it ... -- Mike KB2ML
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HA3HZ
Gwen Patton
