Re: Limiting current to protect finals?
Limiting current? only works if you not seeing voltage spikes.
However when tuning like that you will see voltage spikes
from relays when they transition from open to closed.
In that condition the current can be very low.
Limiting drive MUST be done before tuning as software driven?
limiting means you have to sense it then act on it and that is
far slower than instantaneous.
The AT100 (I have one) is likely the worst auto tuner I've used.
--
Allison
------------------
Please use the forum, offline and private will go to bit bucket.
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Re: Erroneous embedded wattmeter reading
On Fri, May 24, 2024 at 04:55 AM, Carlo Piga wrote:
The bandwidth of the attenuator was 10MHz and I make measurements at 7 MHz.
Carlo, That could very well be the problem.? I don't know the frequency response of your attenuator.? But, a general rule of thumb for an analog measurement is that your bandwidth needs to be 3x that of the signal you are measuring for a flat response.? You report measuring 40V peak and 23W from the embedded meter.? ?So at the radio:? √(100*23) = ~48V.? 40V/48V = 83% at 7 MHz, and per spec your attenuator is 70.7% voltage at 10 MHz. ?I'm just guessing that that attenuator was designed for an application that benefited from a low pass filter. Why not use a 10X scope probe with proper calibration and compensation? With just a dummy load straight connected, does the radio still report a VSWR of 1.2?
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tnx everyone, I found one that works.? Don w8ptb
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does the v3 have a noise blanker??? tnx Don w8ptb
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Re: Erroneous embedded wattmeter reading
Take a look in the raw data read from the ATTiny85 over I2C and check if it makes sense (more power / higher readings, for example), if yes, it is just a matter of software calibration.
- Rafael
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On 5/24/24 10:02, Carlo Piga wrote: I'm setting up a new sbitx v3.
The reading of the embedded power meter is about twice the reading done with the oscilloscope on a 50 ohm dummy load. The "bridge" parameter in user setting ini file is equal 100. If I reduce the parameter I increase the embedder meter reading but I want to reduce it. The maximum value that the bridge parameter use is 100, if I increase over 100 the reading in the embedded meter doesn't change... Anyone have a problem like mine?
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Limiting current to protect finals?
So I cooked a set of finals recently with no obvious reason why.? Most of time my radio uses my raingutters as the antenna, which means I'm using a 9:1 unun with my ATU100 tuner.? When I switch bands the tuner takes a second to do it's thing and for a brief period of time the SWR and power output can be very high.? Gyula mentions that he uses a current limited power supply to reduce these power spikes.? That got me thinking.? I found a chip and made a quick design which could be placed between any standard power supply (battery, AC/DC converter, etc) which would limit the maximum current drawn from the source.? I got a decent way into the PCB design, but then this morning on my drive to work, I got thinking that this approach maybe doesn't do anything...? Help me understand this, I may not have this right in my head:
When transmitting the SDR controls the voltage going into the mosfets in the PA.? The signal goes out the radio hits the antenna and we'll say that this antenna has a very high SWR.? Which means a large portion of the power sent out gets reflected back to the mosfets.? Is that incoming reflection the power increase that we see?? Or is high power during high SWR increasing voltage at the mosfet and pulling more current from the source?
If it's from the source, then I think I can complete this design and have a simple way to add a bit of protection.? If it's just from reflected power, then it's a matter of turning down the drive while tuning, I assume.
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Re: Bringing CW into the 21st Century by Asher Farhan VU2ESE at FDIM and the Future of sBitx
"The more you complain the better the software will get", ha!? He also mentioned that he wants comments in the github.? I have a handful of small things that I'd like to see changed/modified. Guess I'll head over there to make comments.
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He mentions the zBitx and sBitx Hat.
zBitx
Here is a pic of the sBitx hat..
He also mentions the future of sBitx.
- Adding FreeDV mode
- Adding AM TX and RX
- Adding NBFM TX and RX for repeaters, satellites, and transverters
Ashhar also mentions that the more people "complain", then the more will get fixed. His focus is now sBitx software development since V3 hardware has been stabilized. (I think the hardware still has minor QC control issues and design flaws).
After I get the next image of the 64bit version built (expected release is before field day), then I will focus on Ashhar's dev branch and see if I can test/incorporate new features of the sBitx software into the 64 bit build.
73,
JJ
Visit
my repo at ?for
sBitx tools and software.
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Re: Bringing CW into the 21st Century by Asher Farhan VU2ESE at FDIM and the Future of sBitx
He mentions the zBitx and sBitx Hat. zBitx  Here is a pic of the sBitx hat..  He also mentions the future of sBitx.
- Adding FreeDV mode
- Adding AM TX and RX
- Adding NBFM TX and RX for repeaters, satellites, and transverters
Ashhar also mentions that the more people "complain", then the more will get fixed. His focus is now sBitx software development since V3 hardware has been stabilized. (I think the hardware still has minor QC control issues and design flaws). After I get the next image of the 64bit version built (expected release is before field day), then I will focus on Ashhar's dev branch and see if I can test/incorporate new features of the sBitx software into the 64 bit build.
73,JJVisit my repo at??for sBitx tools and software.
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I wasn't super happy with myself for putting the connector on the wrong side.? It will clear the metal brackets, but it's kinda close.? If you aren't happy with that, let me know. I ended up making more boards with the connector going out the other side.?
Glad to know they survived shipping!
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Jeff the board came in yesterday and I can’t wait to get it installed!
The components were unharmed in shipping.
I read your note and couldn’t help but laugh out loud.
There was a long wait and a big fight to get it, I was very lucky to win over 18 others.
I’ll update after I get it installed.
Thanks again!
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To add a bit of nuance....? If you run the radio as it is using only the sbitx software, no fan is needed.? I have been playing with using JTDX with gridtracker, and the pi gets very hot.? Only takes about 45min to hit the 80C max.? I'm planning to add some
cooling to the pi.? But again, if all you use is the built-in software, nothing is needed.
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I agree with Ashhar. I have never encountered any overheating yet.
Scotty WD4PYT?
On Thu, May 23, 2024, 4:05 PM Ashhar Farhan via ?<farhanbox= [email protected]> wrote:
None. The heatsink is enough. I have used it in 110F in the field without a problem.
- f
Having the box from Sbitx, what is recommended for a fan to pull or push the air inside?
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When I first got my license back in the antiquity days of 2013,, the KX3 was pretty much the latest and greatest. I was able to get one and was marveled by what it could do. You could do so much with it and you could spend days exploring the menu system (In my case helplessly being lost in the menu system). Then you had the wonderful little paddles that could plug into the rig itself. The mesmerizing orange glow of the display could give you so much information. Don't get me wrong but the KX3 is truly a wonderful example of electronic engineering.??
Now thanks to people like Ashar, the radio can be so much more. With the sBITX you can have all of your modes and and your internet too. Instead of having to hook the radio up to a computer, the radio is the computer. When you are out on a POTA activation and the Sun attacks the bands and its a beautiful day you can check your email, watch YouTube and check out the latest messages in your favorite io groups.?
Life is good.?
--
'72
Aaron?
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Re: Erroneous embedded wattmeter reading
I'm using the 20:1 attenuator connected with a bnc cable to the input port of the oscilloscope. No probe. The other side of the attenuator is connected to a tee (sbitx and dummy load to the other 2 side of the tee).
In attachments of this message a image of the attenuator.
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Il 24 Maggio 2024 15:26:26 CEST, Raj vu2zap <rajendrakumargg@...> ha scritto:
If you have the original probes then your readings will be
accurate. Otherwise you will need to to calibrate.
I have face this by mixing my various probes.
Raj
On 24/05/2024 5:25 PM, Carlo Piga via
groups.io wrote:
Hi Farhan, I used CW to make measurements. I used
an old CRT oscilloscope with 100MHz bandwidth. The waveform was
well defined on the scope (3÷4 cycle inside the screen). The
bandwidth of the attenuator was 10MHz and I make measurements at
7 MHz.
Thanks for the reply.
Carlo,
Which mode are?you using? It is best to
measure this in CW. You must also check the scope's
bandwidth setting and the time base.
Thanks Evan.
I just update to the latest version. Nothing?
changing...
I will try with a ham wattmeter (that I must buy and
cost the same of the sbitx)...
Bye
Carlo IS0HLX
Il 24 Maggio 2024 12:25:28 CEST, Evan
Hand < elhandjr@...>
ha scritto:
Carlo,
The last thing to try would be to update the
software.? I do not have any other suggestions, as
this is a new first-time power-up.
Maybe Ashhar Farhan or one of the other experts in
the group has other ideas.
73
Evan
AC9TU
|
Bringing CW into the 21st Century by Asher Farhan VU2ESE at FDIM
Checkout Ashhar's presentation at FDIM 2024 ??
73,
JJ
Visit my repo at??for sBitx tools and software.
|
Re: Erroneous embedded wattmeter reading
If you have the original probes then your readings will be
accurate. Otherwise you will need to to calibrate.
I have face this by mixing my various probes.
Raj
On 24/05/2024 5:25 PM, Carlo Piga via
groups.io wrote:
toggle quoted message
Show quoted text
Hi Farhan, I used CW to make measurements. I used
an old CRT oscilloscope with 100MHz bandwidth. The waveform was
well defined on the scope (3÷4 cycle inside the screen). The
bandwidth of the attenuator was 10MHz and I make measurements at
7 MHz.
Thanks for the reply.
Carlo,
Which mode are?you using? It is best to
measure this in CW. You must also check the scope's
bandwidth setting and the time base.
Thanks Evan.
I just update to the latest version. Nothing?
changing...
I will try with a ham wattmeter (that I must buy and
cost the same of the sbitx)...
Bye
Carlo IS0HLX
Il 24 Maggio 2024 12:25:28 CEST, Evan
Hand < elhandjr@...>
ha scritto:
Carlo,
The last thing to try would be to update the
software.? I do not have any other suggestions, as
this is a new first-time power-up.
Maybe Ashhar Farhan or one of the other experts in
the group has other ideas.
73
Evan
AC9TU
|
Good information.
Thank you!
|
Jeff the board came in yesterday and I can’t wait to get it installed!
The components were unharmed in shipping.
I read your note and couldn’t help but laugh out loud.
There was a long wait and a big fight to get it, I was very lucky to win over 18 others.
I’ll update after I get it installed.
Thanks again!
|
Re: Erroneous embedded wattmeter reading
Hi Farhan, I used CW to make measurements. I used an old CRT oscilloscope with 100MHz bandwidth. The waveform was well defined on the scope (3÷4 cycle inside the screen). The bandwidth of the attenuator was 10MHz and I make measurements at 7 MHz.
Thanks for the reply.
Il 24 Maggio 2024 13:27:27 CEST, Ashhar Farhan <farhanbox@...> ha scritto:
Carlo, Which mode are?you using? It is best to measure this in CW. You must also check the scope's bandwidth setting and the time base.
Thanks Evan.
I just update to the latest version. Nothing? changing...
I will try with a ham wattmeter (that I must buy and cost the same of the sbitx)...
Bye
Carlo IS0HLX Il 24 Maggio 2024 12:25:28 CEST, Evan Hand < elhandjr@...> ha scritto:
Carlo,
The last thing to try would be to update the software.? I do not have any other suggestions, as this is a new first-time power-up.
Maybe Ashhar Farhan or one of the other experts in the group has other ideas.
73
Evan
AC9TU
|
Re: Erroneous embedded wattmeter reading
Carlo, Which mode are?you using? It is best to measure this in CW. You must also check the scope's bandwidth setting and the time base.
Thanks Evan.
I just update to the latest version. Nothing? changing...
I will try with a ham wattmeter (that I must buy and cost the same of the sbitx)...
Bye
Carlo IS0HLX Il 24 Maggio 2024 12:25:28 CEST, Evan Hand < elhandjr@...> ha scritto:
Carlo,
The last thing to try would be to update the software.? I do not have any other suggestions, as this is a new first-time power-up.
Maybe Ashhar Farhan or one of the other experts in the group has other ideas.
73
Evan
AC9TU
|
Re: Erroneous embedded wattmeter reading
Thanks Evan.
I just update to the latest version. Nothing? changing...
I will try with a ham wattmeter (that I must buy and cost the same of the sbitx)...
Bye
Carlo IS0HLX
Il 24 Maggio 2024 12:25:28 CEST, Evan Hand <elhandjr@...> ha scritto:
Carlo,
The last thing to try would be to update the software.? I do not have any other suggestions, as this is a new first-time power-up.
Maybe Ashhar Farhan or one of the other experts in the group has other ideas.
73
Evan
AC9TU
|
I wasn’t able to attend FDIM, but I would be interested in getting an sbitx hat if any attendee has one they have changed their mind about using. I would be happy to pay shipping of course, and make a nominal donation to HFSignals and QRP ARCI to help support the biofuels required to advance the project.
72,
Mark KI4HQK
On Thu, May 23, 2024 at 7:24?AM Ravi Miranda via <ravimiranda= [email protected]> wrote: Just checking, as I couldn't make it to FDIM, did the new? driver and
predriver details get discussed or released?
Ravi/M0RVI
On Thu, 23 May 2024 at 04:19, Neil R. Ormos N9NL via
<ormos-lists=[email protected]> wrote:
>
> Bob Bennett wrote:
>
> > I missed part of Farhan's presentation (guys
> > behind me talking too much) but I did get one of
> > the chips that he passed out. I want to set up a
> > project with it but need some more info, pinout,
> > etc. can someone post it.
>
> If you are referring to A F's talk at FDIM, there was an addendum to the FDIM Proceedings entitled "The sBitx Hat" that included that information.? It was distributed with the Proceedings as a separate sheet (unbound), as was the FDIM schedule.
>
> I think the same information is available on the Github site:
>
>? ?<>
>
> The schematic is one of the files listed near the top of the page.
>
> 73
>
> --Neil Ormos N9NL
>
>
>
>
>
--
I'm here to add more value to the world than I'm using up.
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Aaron K5ATG
Raj vu2zap
Bob Brown