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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 2.? I have previously provided some code to avoid unnecessary clattering ofLooking 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: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 IWell. 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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Re: S/N 0994 receiver internal noise
On Thu, Jan 2, 2025 at 01:25 AM, w9blw wrote:
HA3HZ,? That's exactly why. Because of the lack of shielding.
Since there is shielding between the pcb and the RPi and the monitor cable is also shielded, I can now increase the sensitivity to a much higher level without increasing the noise. Of course, increasing the sensitivity also increases the noise, but not as much as without shielding. --
Gyula HA3HZ |
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Thank you for responding, you are the first to report the problem. Indeed, fixing this one line does not solve the problem, as I mentioned it together with the other settings. The monitor ribbon cable and the shielding between the RPi and the pcb greatly improve the quality of the incoming signal. What you did is the first step towards a good solution. I also went through these steps. The device in its delivered state cannot be used as described. What is described in the topic leads to the solution.
Indeed, I started using jtdx around 2017, following the childhood diseases of programming and using the radio, modem, PC I never encountered this message. I was surprised when I searched with google and people complained about similar messages with wsjt-x. Mostly caused by RFI, lack of shielding, tangled wires. In this case, everything is in one place, so a more careful solution was needed. --
Gyula HA3HZ |
On Jan 1, 2025, at 10:55, HA3HZ <gyula@...> wrote:I tried; this was not sufficient by itself, I’m still getting this error. I’ve been using wsjt-x, but I see various people report online that JTDX decodes more signals. I guess that’s why you use it? |
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On Wed, Jan 1, 2025 at 02:43 PM, Mike Johnshoy wrote:
I'd like to give you 2 cents worth on the T/R switch, but I hate to get too many topics going. I'm assuming you are looking at the changes in the 64-bit repo? It might be a good example of code that evolved over time, and several iterations of hardware, that still carries the remnants of good (and less good?) problem workarounds ... My attempt to make things better (I especially like the idea that it seems to get all sbitx hardware back on the same T/R code) should ideally be reviewed and blessed by the original developers. Hi,
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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.?
3.? Here is where I found what MIGHT be the sbitx.c in the 64-bit version: ?
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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.? ?
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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%
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Please correct any misconceptions that you see in the statements (1)(2)(3)(4) above!!? ?On Thursday I will probably try something with reducing the delays, but since my transmitter is currently dead in the water....won't really be able to test for some time....
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Gordon KX4Z
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Re: wipe out - help
Terry,
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If you're looking for the stock firmware(32bit) that ships with the sBitx, you can find it here :
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If you are looking for the 64 bit firmware by JJ and team, you can find it here: ?
I hope you have a backup of the hardware settings as you will need to replace that on the new SD card.
I have had good luck with Sandisk and Samsung EVO cards in the past. I'd suggest a 64GB SDcard, but 32GB card will do just fine. Hope this helps. 73 and Happy New Year, Ragav VU3VWR |
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Re: zBitx is here! Merry Christmas!!
开云体育From HFsignals:Power Supply: 6V to 9V. Receive Current consumption: 300 mATransmit Current consumption: 1.5 to 3A (depending on the Drive settings) There were discussions about modifying the unit to handle higher voltages, but as I recall Farhan made a conscious decision to this voltage range for several reasons, which he explained earlier. Ken, N2VIP On Jan 1, 2025, at 20:32, Chris Hoffman via groups.io <chris.wa2sem@...> wrote:
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Re: zBitx is here! Merry Christmas!!
What is the acceptable range for voltage of the battery/power supply for the zBitx?
I understand that with higher voltages there is the issue with heat dissipation as the voltage is stepped down. Is there any advantage to higher voltage such as higher RF power output? ?
What is the minimum voltage? ?Is a 6 volt LiFePo adequate?? |
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Re: S/N 0994 receiver internal noise
We've discussed this since the V2 days as both of the models suffer from the same issue. There is no shielding whatsoever inside this mass-produced radio which causes all sorts of issues. Mitigating internally generated noise can be accomplished by shielding the DSI cable, replacing the buck converter with a shielded one, making a shield cover for the RF input area, grounding unused pins, etc.
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-JJ |
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Re: S/N 0994 receiver internal noise
HA3HZ,? nice write up, your shielding looks really nice, much nicer than mine. :)? what was the purpose of shielding under the RPI?? Ryan,? i was thinking the same thing, need to shield the whole board.? I just reopened mine and i think we can 3D print a "mold" that we could then cover in shielding tape or paint ( the tape works better in my experience).? Looks really tight with the speaker in there but I'm going to take some measurements and see what i can come up with.? ?the output side will / would be much easier to 3d print a mold for.? thinking jut to keep the ribbons away from the filters if nothing else. w9blw |
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Re: Zbitx boards only
Evan,
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Thanks, I personally have no interest in populated or bare PCBs, I'm happy to help Farhan achieve his social goals, providing meaningful work opportunities to members of his community. When RPi and Displays were hard to source, others and I encouraged Farhan to offer a version without the display or RPi, allowing those with their own display or RPi to supply their own - that was the limit of my interest in home-brewing or recreating his offerings! LOL Thanks for the reminder, I mis-remembered what Farhan does and does not share with the community. Ken, N2VIP On Jan 1, 2025, at 17:35, Evan Hand via groups.io <elhandjr@...> wrote: |
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Re: Zbitx boards only
Yes. ?I would want a bare unpopulated board. ?I don’t intend to sell anything but have plenty of 1206 and 0805 parts and want to experiment here. ?I have already placed an order for a regular zbitx and my sbitx is modified quite a bit so rather than removing a bunch of parts from the zbitx id just start from scratch with another one. ?2 is fine?. ?If the gerber file is available I could buy some from china but would rather just purchase from Ashar. ?
Ryan
kk6dzb |
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Gordon - Thanks for the feedback! The way your note started out I thought it was not going to be good! But it turned out nicely.
re: your results ... 1) Bencher paddle into Sbitx in "Iambic" mode -- seems to key perfectly, very responsive. [The polling rate for the paddle contacts is increased the same as the polling rate for straight key, so good to hear that] 2) Bencher paddle into "lil Bugger" ancient transistor/integrated circuit keyer (no longer on the market) -- with sBitx set to "straight key mode" and the "lil Bugger" doing all the electronic wizardry. This keyer COULD NOT PREVIOUSLY SEND GOOD CODE WITH THE SBITX -- IT JUST ACTED LIKE IT HAD BAD LENGTH CODE ELEMENTS -- I THOUGHT IT WAS NOT PROPERLY SHORTING OUT THE SBITX INPUTS OR SOMETHING AND HAD PLANS TO REBUILD THE OUTPUT CIRCUITRY -- Now, it is sending GREAT CODE! The sBitx is now responding quite well to the Lil Bugger's code. This suggests your fix is a huge improvement to the Straight Key input. [This has been the "acid test", using an electronic keyer to input arguably pefect code into the straigh key jack, and then seeing how bad it gets mangled ... ] 3) Switched to a homebrew Arduino emulator of a WINKEYER (K3NG code) that our group has laid out boards and built. Bencher paddle into Arduino emulator, output into "straight key" mode of sBitx. This is a confirmatory test of the straight key input -- I sent several sentences and the response of the sBitx was snappy and correct! [good, same as your second test] I'd like to give you 2 cents worth on the T/R switch, but I hate to get too many topics going. I'm assuming you are looking at the changes in the 64-bit repo? It might be a good example of code that evolved over time, and several iterations of hardware, that still carries the remnants of good (and less good?) problem workarounds ... My attempt to make things better (I especially like the idea that it seems to get all sbitx hardware back on the same T/R code) should ideally be reviewed and blessed by the original developers. -- Mike KB2ML |
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Re: Zbitx boards only
Ryan and Ken,
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PC board layout and STL files have always been the design pieces that have remained the property of HFSignals. However, there are always exceptions. For example, the original design before the inclusion of the small Pico-controlled screen may be available.
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73/
Evan
AC9TU |
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Re: Zbitx boards only
开云体育You want a "bare unpopulated" PCB?I'm sure you could convince Farhan to share the PCB design once it's finalized... I thought you wanted a PCB with the components installed... Ken, N2VIP On Jan 1, 2025, at 4:10?PM, Ryan Wesolowski via groups.io <cosmo1stgen@...> wrote:
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Re: S/N 0994 receiver internal noise
Good on you for taking this on! ?I know many others will appreciate it also. ?We all just deal with it. ?I have a drok, twisted pair and a ferrite on the display power and a flat ferrite made for ribbon cables on the display cable. ?I have knocked down quite a bit, but the birdies are very annoying more visually than audible for me as you can move them out of the pass band on 4.2 64bit. ?I have a fan case on top of the pi5 that I may add the copper tape to act as a shield and am thinking of trying an aluminum shield between the rf board and display. ?This would cover a good portion of the board. ?
Ryan
kk6dzb |
HA3HZ
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