ps.: if you have the opportunity, use the device from a current-limiting power supply so that it has a long life.
I had to replace the D27 and D28, and then managed to destroy the original IRFZ24Ns, because I used them from a battery, without current limitation.
Since I've been using it with current limitation (12.5V 6.00A), I've made more than a thousand ft8 QSOs on 7-14-21 MHz with a vertical Loop antenna.
I've been using it since mid-November.
--
Gyula HA3HZ
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Lorenzo,
? I'm just guessing the cause of the problem because I can't do it to see and measure it.
Please remove the pcb from the housing (so that the housing is not damaged during soldering).
There are two ferrite rings near the antenna connector and a diode (D27, D28) nearby.
You should measure these diodes at direct current. You can easily unsolder it and put it back in the same way.
They provide the control signal for the output signal measurement.
These are 1N63 or 1N60 type Ge diodes. If these are damaged, there is no output signal status display.
If you manage to get it, it is worth selecting ones with almost the same conductivity and incorporating them.
Don't ask how I know.
--
Gyula HA3HZ
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I used this small PCB in my 6 mtr bitx, the settings I used are likely in the video:
Chris PA3CRX
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Hi Ashhar, I checked and even at 100 I got no output. I attach a screenshot. Thank you! Lorenzo 
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Re: ubitx audio amp problem discovered
There emitter follower's base can directly couple to the original's collector. - f
Farhan,
? ?Would you sanity check this, please? It's the uBITX V6 mic amp through C63 with a buffer pulled from Eamon Skelton's book.? Did I translate your suggestion accurately?
? ? Thanks and 73,
? ? ?Andy
On Sat, Jul 15, 2023 at 09:18 PM, Ashhar Farhan wrote:
Thanks for the analysis. There are two other significanr issues with the current mic amplifier.
1. The output impedance is 1000 ohms, the modulator needs a 50 ohms drive.
2. The gain is not less but too much. The electrer mic produces about 50mV of audio, the modulatoe needs less than 150mv drive. A gain of two or three is more than sufficient. The apparent loss is due to the mismatch between the 1000 ohm output and the needed 50 ohms drive.
These can be solved by adding an emitter follower with a 47 ohms resistor in series with the output of the emitter follower and removing the emitter bypass of the original mic amplifier.
- f
I've been working on the uBitx audio circuit for a while now and I think I've discovered a problem that I've never seen anyone mention before. If anyone has experience with this circuit, please review and let me know if I've missed anything. Here are my notes:
?
?Audio Amp notes.
?
The uBitx has always had challenges with the audio amp. It has insufficient gain for the condenser mic that is provided. Solutions include:
?
a. Use a mic with an amplifier built in.
b. Add an additional amplification stage such as the SSM2167.
c. Increase the mic circuit gain.
?
Mic amplifier circuit with suggested modifications. Also showing the load of the following stage.
?
SEE ATTACHED FILE
?
Analysis:
Given that the receive transistor Q70 is connected directly to the output of the microphone amplifier, the output of the mic amp must be less than 0.6v. We¡¯ll say 550 mV to give us a bit of safety margin.
The input drive required to achieve 550mV out of the mic amp is 200mV. Most have claimed that the mic amp has a gain of around 20 due to the collector resistance of 1k divided by the emitter resistance of 47 ohms. This simple analysis is incorrect because it neglects the load impedance of the mixer circuit. Spice analysis and actual observation shows the actual gain to be about 2x or 3x.
A big problem with this mic amplifier is that it is incorrectly biased. With the originally specified bias resistor R61 set at 2.2k, the transistor runs out of emitter current at about 160mV of output voltage. In addition to limiting output, this causes distortion of the audio waveform. By increasing R61 to 10k, the circuit can easily output the 550 mV (1.1V P-P) originally suggested.
In my own uBitx, I have chosen to use the SSM2167 as a preamp in order to enjoy some voice compression. However, the simplest solution is to decrease R63 to 10 to 22 ohms. I¡¯d advise not to go lower than 10 ohms, since that circuit should fully drive the mixer with a mic output of only 40 mV. But before doing anything else, increase R61 to 10K.
?
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I noted a recent email suggesting that we go with the latest processor and matching software.? That might be nice, but it's just like with cars,? We might all like a new Rolls-Royce or Ferrari (take your pick of other similar manufacturers), but the budget says we might have to settle for a second hand Ford.? I'd even settle for that today - my driving days are over - lost my driver's license - age-related medical issues.? Let 's all do the best we can with what we have, and help some of the less fortunate ones enjoy the hobby too.? I very recently provided some software I created, and it will be going up on the local radio club's web site, in case anyone thinks I don't do anything any more.
Gerry Sherman
Sent by the Windows 11 Thunderbird
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On Mon, Feb 5, 2024 at 02:17 PM, JJ - W9JES wrote:
I encourage you to update the app and let me know how it goes.
sBITX-toolbox has updated to v1.6? no problems this time JJ, and what I have tried? so far is working as expected. [thumbs-up] ? -- Pete VK3PYE
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Re: ubitx audio amp problem discovered
Farhan, ? ?Would you sanity check this, please? It's the uBITX V6 mic amp through C63 with a buffer pulled from Eamon Skelton's book.? Did I translate your suggestion accurately? ? ? Thanks and 73, ? ? ?Andy 
On Sat, Jul 15, 2023 at 09:18 PM, Ashhar Farhan wrote:
Thanks for the analysis. There are two other significanr issues with the current mic amplifier.
1. The output impedance is 1000 ohms, the modulator needs a 50 ohms drive.
2. The gain is not less but too much. The electrer mic produces about 50mV of audio, the modulatoe needs less than 150mv drive. A gain of two or three is more than sufficient. The apparent loss is due to the mismatch between the 1000 ohm output and the needed 50 ohms drive.
These can be solved by adding an emitter follower with a 47 ohms resistor in series with the output of the emitter follower and removing the emitter bypass of the original mic amplifier.
- f
I've been working on the uBitx audio circuit for a while now and I think I've discovered a problem that I've never seen anyone mention before. If anyone has experience with this circuit, please review and let me know if I've missed anything. Here are my notes:
?
?Audio Amp notes.
?
The uBitx has always had challenges with the audio amp. It has insufficient gain for the condenser mic that is provided. Solutions include:
?
a. Use a mic with an amplifier built in.
b. Add an additional amplification stage such as the SSM2167.
c. Increase the mic circuit gain.
?
Mic amplifier circuit with suggested modifications. Also showing the load of the following stage.
?
SEE ATTACHED FILE
?
Analysis:
Given that the receive transistor Q70 is connected directly to the output of the microphone amplifier, the output of the mic amp must be less than 0.6v. We¡¯ll say 550 mV to give us a bit of safety margin.
The input drive required to achieve 550mV out of the mic amp is 200mV. Most have claimed that the mic amp has a gain of around 20 due to the collector resistance of 1k divided by the emitter resistance of 47 ohms. This simple analysis is incorrect because it neglects the load impedance of the mixer circuit. Spice analysis and actual observation shows the actual gain to be about 2x or 3x.
A big problem with this mic amplifier is that it is incorrectly biased. With the originally specified bias resistor R61 set at 2.2k, the transistor runs out of emitter current at about 160mV of output voltage. In addition to limiting output, this causes distortion of the audio waveform. By increasing R61 to 10k, the circuit can easily output the 550 mV (1.1V P-P) originally suggested.
In my own uBitx, I have chosen to use the SSM2167 as a preamp in order to enjoy some voice compression. However, the simplest solution is to decrease R63 to 10 to 22 ohms. I¡¯d advise not to go lower than 10 ohms, since that circuit should fully drive the mixer with a mic output of only 40 mV. But before doing anything else, increase R61 to 10K.
?
|
On Sun, Feb 4, 2024 at 07:29 PM, Ashhar Farhan wrote:
JJ,
Just a reminder, you Can read the tuning knobs too from your suite to choose through settings, et al.
Thanks and yes I figured out a way to do it and plan to add it in a later release..  -JJ
|
On Sun, Feb 4, 2024 at 05:07 PM, Peter VK3PYE wrote:
On Fri, Feb 2, 2024 at 01:14 PM, JJ - W9JES wrote:
sBITX Toolbox version 1.4 is now available.
Hi JJ, after using the update menu item, mine is now set to v1.3, and says it is the latest version. Bug?
Enjoying your work mate ;-)?
--
Pete VK3PYE
Hello Peter and thanks trying out the app. I realized there was an issue in the way that updates were pushed out (I accidentally pushed the incomplete updates from my dev branch). I believe this issue is now resolved in version 1.6. I also added some troubleshooting steps in the guide to force updates and fix other issues. I encourage you to update the app and let me know how it goes. -JJ
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Version 1.6 is now available for download or update.
There were some major changes in this release. Please see the release notes for information.??
-JJ
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About 1 in 5 uses of sbitx v3 unchanged from factory, I get no tx output ( only use ft8) as well. Restarting sbitx does not fix the problem. I must reboot the system to fix the problem.?
On Sun, Feb 4, 2024 at 15:39, assali_fucina_0h via groups.io < assali_fucina_0h@...> wrote: Hi, my name is Lorenzo and I write from Italy.
This is my first message here, so nice to virtually meet you all!
I have a sBitx v3 board SN 0634, and while I'm 3D printing the case, I did some tests, after upgrading to v3.02.
It works perfectly in RX, in all modes I tested (SSB, CW and FT8) but when trying to transmit I got no output at all. The power meter reads 0W and SWR 1.0.
I tried it in FT8 and CW, and when switching to TX, the supply current rises from 400mA to 1.2A, but I have no power on the BNC connector. I tested with a tuner with built-in wattmeter, using my antenna and a 50W dummy load, no changes at all, regardless to the Drive setting.
The waveform display only shows a yellow straight line, without any modulation. As I'm an absolute beginner in the sBitx world, I don't know if I'm missing something. I checked the IRF510s and they seem fine. I also measured the voltage between Gate and Source while switching to TX, and it reads 4.33V, so I suppose the TX switching works fine. Any idea is greatly appreciated! Thanks!?
?73 de IU5RDU!
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Lorenzo, Can you check that the drive level is 100 on cw? - f
On Mon, Feb 5, 2024, 3:15 AM Lorenzo IU5RDU via <assali_fucina_0h= [email protected]> wrote: Sorry, I forgot to add that I'm currently using an HDMI monitor (without audio) and I already tried to add the "noaudio" parameter to the config.txt file.
Thanks
Lorenzo IU5RDU
|
JJ, Just a reminder, you Can read the tuning knobs too from your suite to choose through settings, et al.
On Mon, Feb 5, 2024, 4:37 AM Peter VK3PYE < vk3pye@...> wrote: On Fri, Feb 2, 2024 at 01:14 PM, JJ - W9JES wrote:
sBITX Toolbox version 1.4 is now available.
Hi JJ, after using the update menu item, mine is now set to v1.3, and says it is the latest version. Bug?
Enjoying your work mate ;-)?
--
Pete VK3PYE
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Have an extra V.5 board to part with?
My project, based on a version 5 mainboard, is having problems I can't seem to get past. I think I'd like to do some rework anyway and a clean start would help.?
If anyone has a V.5 board they want to sell off, let me know.
Tnx.
K3RTA
|
On Fri, Feb 2, 2024 at 01:14 PM, JJ - W9JES wrote:
sBITX Toolbox version 1.4 is now available.
Hi JJ, after using the update menu item, mine is now set to v1.3, and says it is the latest version. Bug? Enjoying your work mate ;-)? -- Pete VK3PYE
|
Re: Radio S32LE samples don't go negative?
All you have to do is take the average and subtract it from each of the values¡.
toggle quoted message
Show quoted text
On Feb 4, 2024, at 16:30, Dave, N1AI <n1ai@...> wrote:
?On Sun, Feb 4, 2024 at 04:07 PM, Gordon Gibby wrote:
Those are 24 bit a to D ?converters. ?They have 80 to 90 DB dynamic ranges from the spec sheet. They are 30 or 40 or 50 DB more than we need!
?
Some people are selling systems with only eight bit eight bit ADC and that sounds pretty crappy but these are astonishingly good
I think my posting history shows I have a lot of Linux system programming and performance tuning in my background, not much DSP. At my last job before retirement I did work with a bunch of professional DSP engineers, but they spoke a different language than I did.? I spoke in terms of Linux, C and Python, they spoke in terms of MATLAB and Vivado.?? When I bought sbitx I thought I'd be spending most of my time using it to teach myself more about DSP.? That hasn't been the case so far. I think we do have enough dynamic range, but we also have Rafael's statement that the DSP code he's using has problems due to the all-positive data they are being fed to them. I think he also said he could scale the data if he knew what scaling factor to use, but didn't know how to come up with a good scaling factor. Ideally this project would have access to one or more DSP engineers it could call on that could explain such things to C programmers. I can think of one, but don't have his email address! :-) ? -- Regards, Dave, N1AI
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Re: Issue #4 Raspberry Pi 4 HDMI audio modules conflict with loopbacks
Folks;
I have a hack available that may help with sbitx audio output device experiments at
This code will accept an optional command line parameter to select a specific audio device.
To test it, I plugged in a dirt-cheap USB audio "thumb-size" sound card. lsusb shows it as:? Bus 001 Device 004: ID 0d8c:0014 C-Media Electronics, Inc. Audio Adapter (Unitek Y-247A)
Looking at the /var/log/syslog indicated that a new device hw:4,0 was created.
I then started the sbitx program with $ ./sbitx plughw:4,0
After a bit of settling, the receiver was heard on the left channel of my headphones that were plugged into the USB sound card.
This code is really meant to be used as a tool to experiment with using other sound devices for audio output. It may be possible to get a bluetooth device to work, but it seems that bluetooth in general is kinda fussy on a raspberry pi.
73; Steve, N3SB
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Goulash and others, I just ordered it too. I have spent way too much time tried multiple microphone's.? Swapped out the Electret element 3 times on 2 different Baofeng mikes. Including trying a dynamic with 2 different pre amps with varying results and making the suggest resistor changes . Hoping the Max board will make it easier and the compression option finally swayed me. I'm not complaining my V6 has taught me so much and still is.
Owen Vk5kov
Gyula,
Sounds good on the 3 settings. I might have to get a couple of thee critters and try them .
good luck Ashok and pleasant Hamming!!!
73 David ac9xh
On Sunday, February 4, 2024 at 12:50:14 PM EST, HA3HZ < gyula@...> wrote:
I would listen to my broadcast . This way, the setting will be personalized.
--
Gyula HA3HZ
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Sorry, I forgot to add that I'm currently using an HDMI monitor (without audio) and I already tried to add the "noaudio" parameter to the config.txt file.
Thanks
Lorenzo IU5RDU
|
HA3HZ
Peter VK3PYE
Ted