Thank You: Re: Was Wondering: Re: [BITX20] A Path Toward Adding a Noise Blanker and More?
Evan:? Sorry, I reply to the other message instead of this one.?
Thank you for the information and clarification. This and the following one were both beneficial.?
73 Dave WD8AJQ
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On Oct 3, 2022, at 5:06 PM, ajparent1/kb1gmx <kb1gmx@...> wrote:
?uBitx band filtering is bi-directional and the same in both directions (RX/TX).
The usual noise blanker (Lamb) samples RF/noise from the antenna and if?
Pulse in nature it operates a FAST RF switch to interrupt the signal for a
short time usually befor ethe primary selectivity..? Hence the name blanker.? ?
There are designs on the net. Generally the biggest difference between
them is the devices used to switch?usually diodes or can be transistor
or fet.? IT is useful for pulse noise but not hash from things like
switching power supplies or other electronic crap.
Allison
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Please use the forum, offline and private will go to bit bucket.
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Re: Suddenly no receive on my sBitx - what are steps required to resolve this?
Ashhar,?
I hate to ask stupid questions but now that I think I understand what U3 is doing, why is it there at all ? simply connecting the RX relay side if C14 to the U3 pin 3 side of C4 and removing R14 would eliminate the need for U3. Unless I'm not understanding what U3 does, its just putting the antenna to ground. relay K9 is going the exact came thing minus a 0.1 cap. Your thoughts ?
KC7GRH
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Thank You: Re: Was Wondering: Re: [BITX20] A Path Toward Adding a Noise Blanker and More?
Evan:? Thank You for the info and clarification.?
73 Dave WD8AJQ
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On Oct 3, 2022, at 2:44 PM, Evan Hand <elhandjr@...> wrote:
?David,
The filters switched in the uBitx are low-pass filters (LPF).? They reduce any signal above the desired frequency, like unwanted harmonics generated by the transmitter.? Most AM interference is below the HF bands.? There are exceptions overseas.? You will still need a broadcast interference (BCI) filter if you are close to a commercial AM station.? The same would be true for the sBitx.
Note that there are more filters in the design for both radios.? These include a 30MHz low pass filter used by both the receiver and the transmitter and crystal filters used to reduce the bandwidth that must be decoded.
73
Evan
AC9TU
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Re: Suddenly no receive on my sBitx - what are steps required to resolve this?
Ashhar,?
No I have not tried putting the antenna directly to c94 yet. Today my radio is receiving static and noise even on dummy load. Intermittent problems are so hard to troubleshoot?
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Re: Suddenly no receive on my sBitx - what are steps required to resolve this?
Ashhar,
I was just reading the specs on U3. It says in the specs, The break?before?make select circuitry prevents disruption of signals on the B Port due to both switches temporarily being enabled during select pin switching. Is this going to put TX POWER directly into the receive circuit. I understand that U4 controls the RX relay but how long does it take the RX relay to switch from RX to TX. Just a thought
KC7GRH
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Re: Suddenly no receive on my sBitx - what are steps required to resolve this?
Have you tried connecting the antenna directly to c94?
On Tue, Oct 4, 2022, 9:21 AM Butch < kc7grh@...> wrote: Ashhar,
My unit ch0128 goes from working normally to not receiving any signals to red to yellow on the waterfall even when on a dummy load.? It still receives stronger signals when its yellow. Transmit seems to be fine although I keep the power down to QRP.
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Re: Suddenly no receive on my sBitx - what are steps required to resolve this?
Ashhar,
My unit ch0128 goes from working normally to not receiving any signals to red to yellow on the waterfall even when on a dummy load.? It still receives stronger signals when its yellow. Transmit seems to be fine although I keep the power down to QRP.
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Re: Gtk-WARNING: cannot open display (./sbitx)
Shout out to K3NG (and thanks for your efforts)
just to let you know that your sbitx code also gets stuck when the process is trying to start up.
Again this is with the original RPi 4 and a new downloaded image and a new sd card, without any modifications.?
yet the same RPi 4 was working 3 weeks ago, and yesterday I swapped in an old RPi 3 and it worked. (Reinstalled the RPi 4 and the problem continued so I¡¯m convinced the RPi 4 is the problem¡unless someone has a suggestion for a fix.)
I understand that everyone is busy with the sBitx for other reasons, but mine is unusable now with the supplied RPi 4 and I don¡¯t want to buy another RPi 4. Any clues would be greatly appreciated!
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Re: Use driver stage as PA.
#sBitx
Unwind one turn from the PA secondary like Allison has recommended. I would also reduce the 10 ohms (two paralleled 22 ohm resistors) to 47 ohms by snipping off the resistor leads from one side and moving them away and soldering 47 ohms )or two parallel 100 ohms instead. The gate resistors are used to swamp out the high gate-source capacitance. It is much lower with the IRF510s. Further, I think the proper drive for the IRF510s should come from a capacitors directly connected to the collectors of the push-pull drivers. That would transfer more power, instead of the secondary of T5 secondary. See my "hen sketch" as Allison calls it. - f
I tried the 510 but they went bad very quick.?
What changes would you recomend if using 510 in place of the irfz24?
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Re: Use driver stage as PA.
#sBitx
I tried the 510 but they went bad very quick.?
What changes would you recomend if using 510 in place of the irfz24?
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Re: Use driver stage as PA.
#sBitx
At these power levels, the IRF510 gain will be much better as it has half the internal capacitance of the IRFZ24N
I did not modify t5. Looking into other designs, they use broadband transformer on the input. Later will try it.
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Re: Use driver stage as PA.
#sBitx
I did not modify t5. Looking into other designs, they use broadband transformer on the input. Later will try it.
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Re: Use driver stage as PA.
#sBitx
I am surprised at the low output on 80 M. Any reason?
Found another set of irfz24 and went in a similar way to your experiment, but using the actual finals and remove the driver section.? For this I removed c30, c32, c100 and c101. Then from the back of the board conected the output of t5 to the finals gates using 100nf caps.?
These are the outputs...
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Re: Sbitx #165 received today, thoughts.
With Anthony' move to isr reading the key/paddle hardware,we can move to almost real-time. Here is how: 1. His ISR sets a flag. 2. Our audio loop in tx_process or rx_process can check the flag very inexpesnively and sharp moving the envelope up or down.? Btw, note that the shaping is a perfect raised cosine and you can vary the rise/fall time from the code. Anthony, you can probably add that command to the codebase. The sound loop runs at the highest thread priority and we should not do anything it in expect the dsp stuff. At least not inside the rx_process and tx_process. - f
On Tue, Oct 4, 2022, 6:58 AM Evan Hand < elhandjr@...> wrote: In my past, with process control, these problems were solved by having Fast, Slow, and maybe medium speed loops based on a timer interrupt.? That ensures the fast loop is executed on a minimum cycle time, and any extra process capability is used to process the other loops.? The priority is self-evident.? This gives predictability (determinism) for things like high-speed digital and PID control that need either a fast response or deterministic responses.? Using time stamping is a way to improve deterministic response capabilities.? You still need to manage the process timing to ensure that all functions can be performed in the time required.? My way of thinking is using the RPi to implement 2 or three Nano equivalents with loop executions that are fast enough to do what is required.
73
Evan
AC9TU
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Re: Use driver stage as PA.
#sBitx
Found another set of irfz24 and went in a similar way to your experiment, but using the actual finals and remove the driver section.? For this I removed c30, c32, c100 and c101. Then from the back of the board conected the output of t5 to the finals gates using 100nf caps.?
These are the outputs...
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Re: Sbitx #165 received today, thoughts.
In my past, with process control, these problems were solved by having Fast, Slow, and maybe medium speed loops based on a timer interrupt.? That ensures the fast loop is executed on a minimum cycle time, and any extra process capability is used to process the other loops.? The priority is self-evident.? This gives predictability (determinism) for things like high-speed digital and PID control that need either a fast response or deterministic responses.? Using time stamping is a way to improve deterministic response capabilities.? You still need to manage the process timing to ensure that all functions can be performed in the time required.? My way of thinking is using the RPi to implement 2 or three Nano equivalents with loop executions that are fast enough to do what is required.
73
Evan
AC9TU
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One of the first things I checked too. Apparently I was sloppy and measured from the surface of the blocks. When there was no continuity, I assumed black plastic blocks. I just checked more carefully, from screw to screw and, yes, there is continuity but due to the paint under the screw heads, the panels are floating.
Joe
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I have posted a development code update. Some of the items are a bit obscure:
- created submit_field_size_and_position_adjust() and implement_field_size_and_position_adjust() for adjusting and moving fields on screen
- updated struct field, new variables int enabled and int size_or_position_change_flag
- made help screen code look nicer
- added WINDOW_X, WINDOW_Y, and other WINDOW_ DEFINES to start to handle different screen geometries (work in progress)
- moved some initial console messages from main() to ui_tick() in order to handle issue with long strings and word wrap printed to the console prior to gtk_main() starting
However there are two UI items:
- updated init_waterfall() so waterfall is entirely black upon initialization (bug fix?)
- added \sdh [0-100] command to adjust spectrum display height
My last few days coding haven¡¯t been super productive as I¡¯ve gone down some rabbit holes. I attempted again to figure out why the tuning control goes faster when turning counter-clockwise versus clockwise. There is definitely a bug somewhere and it wasn¡¯t introduced with my tuning acceleration code. I¡¯ve noticed the waterfall accelerates scrolling when tuning down as well. I think I spent three hours on Sunday trying to figure out what is going on, and this code isn¡¯t complicated. If anyone else is looking at this issue in the code, please email me privately.
I¡¯ve put some code in place to make moving and resizing controls at runtime easier, and I¡¯m going to start experimenting with some optional alternative UI arrangements.
Rest assured, I¡¯m not going to wreck the current default UI in my development version.
Some things on my short term to do list:
Fix \addcwpitch
Max power setting (temporary while we¡¯re working through final PA issues)
VOX / BK IN control
Optional One band button
Optional focus back on volume after a timeout
Finish \s settings command
Longer term to do list:
BW and CENTER filter buttons in CW & CWR mode
WIDE and NAR filter presets by mode
TUNE button and \tune command
CQ Autorepeat
More CW improvements
Sorry for the long post. To try the code:
cd /home/pi
git clone
cd sbitx-k3ng
git pull
./build sbitx
./sbitx
73
Goody
K3NG
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Re: Sbitx #165 received today, thoughts.
True,? cascade threading is sometimes for code efficiency or other uses but?
not always performance.? It can be a whole other process with interprocess
communication and linux is fairly rich with ways to do that.? Assuming only
one way is why we get to things like that.
One possible way to create a bottleneck is code a section of the over all
task as a scripting or interpreted language to make the coding easier.
Happened on a project I worked,? someone added a segment that was
not in the working language (C+) as a stopgap and it was merged by error.
IT only worked as it was Lua and that was part of the project but high level
user scripting use where slower was just fine.?
Over all its not an issue and bigger fish need to be fried.
Allison
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Please use the forum, offline and private will go to bit bucket.
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Re: sbitx Board Problem - support needed
#sBitx
Allison,
I, too, am scratching my head to ascertain the cause of the failure.? I am also considering using a beefier BS170 (2) in parallel as an option (I already have those in my parts supply).? I need to do the parameter evaluation before I solder.
Are you aware of the reason for adding the 2n7000 in parallel with Q10?? Is it a current issue?
Any advice would be appreciated.
73
Evan
AC9TU
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Butch
John Terrell, N6LN
