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Re: sBitx v3 - original application gives high power, wsjtx up to 2W only

 

I set the mode to USB in the sbitx application and the maximum power is still 2W.
The slider in wsjtx still controlls the power.
?
73,
Wojtek
Re: sBitx v3 - original application gives high power, wsjtx up to 2W only

 

Wojtek,
Set it to USB and you can set the output power with the Drive value. The wsjtx slider does not work with sbitx, the Drive is the determining factor.
?
--
Gyula HA3HZ
sBitx v3 - original application gives high power, wsjtx up to 2W only

 

Hi,
?
Due to the problems with non-standard callsigns, I have decided to use wsjtx.
I have updated sbitx with the `update` script.
?
I start it via VNC.
  1. I installed tigervnc on my sBitx
  2. I log in to my sBitx via: `ssh pi@... -L5907:localhost:5907`
  3. In another console on PC I run: `vncviewer :7`
  4. Then in the vnc session in a terminal I run:`killall sbitx; cd ~/sbitx; sleep 1; ./sbitx`
  5. In another console I run `export DISPLAY=:7 ; wsjtx`
  6. The wsjtx is configured as described here:
  7. I set Digital mode in the sbitx and FT8 in wsjtx.
The result is that I can see the received FT8 messages, I can transmit, but the power is limited to 2W (as reported by sbitx).
I can control the power with the slider in the wsjtx window. The power is proportional to the slider position, but the upper position gives 2W.
?
When running only the original sbitx application, I can control power up to 20W and higher.
What is the reason of that problem and how can I cure it?
?
73,
Wojtek
Re: reviving my sbitx v3

 

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Yes, it can be quite confusing. It's also possible that an errant hot wire from a bench psu touched somewhere. I had to step back from this one for a while, because I was beginning to get frustrated and we know where that can go! So I decided to work on assembling a K9HZ 20w pa board that I will probably drive with my Lime mini 2. I also have a radioberry 2 that I am working on getting configured properly. So with the three different projects going at once, I can always move to another when I start getting frustrated and tired of one.






-------- Original message --------
From: "Gordon Gibby KX4Z via groups.io" <docvacuumtubes@...>
Date: 3/14/25 6:41 PM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3

Sounds like another case where something is screwy.

I don¡¯t think you could blow D7 unless you had reverse polarity power.
?
so there may be a mislabeling or a screw circuit board here. Or maybe just a mistake in figuring out where things are blown.
?
but all of these combined to make it extremely difficult to figure out what the heck is going in very carefully measure and look and pride and think and compare figure out what really is blown and what isn¡¯t and where it is really connected and where it isn¡¯t!!
?
we¡¯ve already seen one example where this unit was wired differently from everybody else. ??
?
gordon Kx4z?

--
Mike - K8MCB?
Re: uBITX v6 Low Audio - Back at it again

 

Re: reviving my sbitx v3

 

Sounds like another case where something is screwy.

I don¡¯t think you could blow D7 unless you had reverse polarity power.
?
so there may be a mislabeling or a screw circuit board here. Or maybe just a mistake in figuring out where things are blown.
?
but all of these combined to make it extremely difficult to figure out what the heck is going in very carefully measure and look and pride and think and compare figure out what really is blown and what isn¡¯t and where it is really connected and where it isn¡¯t!!
?
we¡¯ve already seen one example where this unit was wired differently from everybody else. ??
?
gordon Kx4z?
Re: reviving my sbitx v3

 

Mike,
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D7 is for reverse polarity protection.? It should not blow unless the power is connected wrong.??
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I had trouble adjusting the bias on my DE sbitx.? The TR switching was not working correctly, allowing the amp to enter sustained oscillation.? The amp does not amplify until the bias is close to correct and the oscillation begins.
?
I would verify that both sections of the TR switching (Q9, Q28, Q29, and associated transistors).
?
73
Evan
AC9TU
Re: reviving my sbitx v3

 

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So, everything is still switching, but...when I was attempting to adjust the bias, which was about 800mA in receive, and about 1.2A with PTT engaged, in USB, 40m drive at 1 mic at 0. When I began to adjust cw from the full ccw position, the pot didn't do anything until over half a turn, and immediately jumped to 3-5A, and proceeded to pop D7.
?If it's not one thing, it's another!!! Anyway, both D30 and D31 are both OK, dropping about .6v each. Aside from checking Q28 and the 2 finals, what else could be the issue, other than the likely blown pot for the bias?






-------- Original message --------
From: "Evan Hand via groups.io" <elhandjr@...>
Date: 3/14/25 2:00 PM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3

Mike,
?
As Gordon points out, there is most likely a problem with the receiver TR switch.? As with the transmitter switching, verify the operation of Q28.
?
You can also try removing the RF from the circuit with a low drive setting.? Set it up as shown on the voltage measurement sheet.
?
If Q28 turns on and off with the PTT signal, then look at the diodes themselves.? You should be able to check the diode in the circuit without power.
?
It is good you found this before being forced to replace another set of finals and other components.
?
73
Evan
AC9TU
?

--
Mike - K8MCB?
Re: Chirpy audio in ubitx6.1 #bfo #ubitxv6 #v6

 

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That¡¯s the ham radio spirit!! Congrats !!

Gordon kx4z


On Mar 14, 2025, at 14:43, Praba Karan via groups.io <vu3dxr@...> wrote:

?
Found a cure for this defect. I have disabled existing LM386 audio amp and used TDA2822 amp module. I took audio input from IC socket pin 3 without any surgery. Now audio is good. The only issue is slightly lower audio level and yet to find ?space for audio module inside cabinet.
Re: Chirpy audio in ubitx6.1 #bfo #ubitxv6 #v6

 

Found a cure for this defect. I have disabled existing LM386 audio amp and used TDA2822 amp module. I took audio input from IC socket pin 3 without any surgery. Now audio is good. The only issue is slightly lower audio level and yet to find ?space for audio module inside cabinet.
Re: reviving my sbitx v3

 

Mike,
?
As Gordon points out, there is most likely a problem with the receiver TR switch.? As with the transmitter switching, verify the operation of Q28.
?
You can also try removing the RF from the circuit with a low drive setting.? Set it up as shown on the voltage measurement sheet.
?
If Q28 turns on and off with the PTT signal, then look at the diodes themselves.? You should be able to check the diode in the circuit without power.
?
It is good you found this before being forced to replace another set of finals and other components.
?
73
Evan
AC9TU
?
Re: reviving my sbitx v3

 

¿ªÔÆÌåÓý

They should be back biased by the high-voltage supply. Either it¡¯s not working or there might be a problem around Q 28, haul out the voltmeter meter and start looking at voltages in receive and in transmit and figure out what¡¯s going on.

Study the schematic to understand how the switching works

Good luck!!!

Gordon kx4z



On Mar 14, 2025, at 11:49, Michael Bales via groups.io <mikebales73@...> wrote:

?

Evan, doing a once over before setting the PA bias, I noticed that I am getting excessive heating of D30, D31 upon Tx. I still have output from the finals. It could be heating elsewhere as well, but I didn't want to leave it on Tx any longer than needed until I can id the problem.?

Mike


From:[email protected] on behalf of Evan Hand via groups.io
Sent:?Thursday, March 13, 2025 10:25 PM
To:[email protected]
Subject:?Re: [BITX20] reviving my sbitx v3

To be clear, both the receiver and the transmitter use that mixer.? It translates the signal from the 40MHz IF frequency to the operating frequency in both directions.
?
73
Evan
AC9TU

--
Mike - K8MCB?

Re: reviving my sbitx v3

 

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Evan, doing a once over before setting the PA bias, I noticed that I am getting excessive heating of D30, D31 upon Tx. I still have output from the finals. It could be heating elsewhere as well, but I didn't want to leave it on Tx any longer than needed until I can id the problem.?

Mike


From:[email protected] on behalf of Evan Hand via groups.io
Sent:?Thursday, March 13, 2025 10:25 PM
To:[email protected]
Subject:?Re: [BITX20] reviving my sbitx v3

To be clear, both the receiver and the transmitter use that mixer.? It translates the signal from the 40MHz IF frequency to the operating frequency in both directions.
?
73
Evan
AC9TU

--
Mike - K8MCB?
Re: Chirpy audio in ubitx6.1 #bfo #ubitxv6 #v6

 

I tried both mods.
Not much improvements in audio quality.
I observed 59++ signals doing good with little distortion. Signals below 58 are heavily distorted.
?I have some small TDA2822 and LM 1875 amp modules in my junk. If I want use them as audio amp bypassing LM386, from where I take audio input?.
?
?
Re: Chirpy audio in ubitx6.1 #bfo #ubitxv6 #v6

 

Hello Praba,
?
Two possible mods might help:
1 - Add a 10uF capacitor across C75.? If electrolytic, the + goes to pin 1. (see 9.2.2 in the datasheet)
2 - Add the bass boost circuit described in the TI LM386 datasheet section 9.2.5.
?
?
73
Evan
AC9TU
?
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Re: Trying to update firmware in ubitx6.1 #v6

 

Issue fixed...
what i did is just made hex file from arduino IDE after compiling and the upload said hex file via Xloader.
success.?
Re: reviving my sbitx v3

 

¿ªÔÆÌåÓý

Makes sense. It does seem rather touchy and the effect on signal strength of the received signal is more like an on/off switch than a range, like you might expect. Anyway, it works and I am now comfortable proceeding with the bias adjustment and band specific drive adjustment for the PA. Let me know if there is anything that I should be looking out for while I go through the process.?






-------- Original message --------
From: "Evan Hand via groups.io" <elhandjr@...>
Date: 3/14/25 1:26 AM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3

To be clear, both the receiver and the transmitter use that mixer.? It translates the signal from the 40MHz IF frequency to the operating frequency in both directions.
?
73
Evan
AC9TU

--
Mike - K8MCB?
Chirpy audio in ubitx6.1 #bfo #ubitxv6 #v6

 

The attached is Rx audio of my ubitx v6.1. Audio is too chirpy and unpleasant to hear. But Tx audio is good as per other hams reports. I tried several bfo adjustments. Anyone help me to rectify the issue.
Rx video clip? -

VID_20250314_074817.mp4
VID_20250314_074817.mp4

Re: reviving my sbitx v3

 

To be clear, both the receiver and the transmitter use that mixer.? It translates the signal from the 40MHz IF frequency to the operating frequency in both directions.
?
73
Evan
AC9TU
Re: reviving my sbitx v3

 

¿ªÔÆÌåÓý

I figured it had something to do with the reception, as when I first turned it back on and the receiver appeared to be "deaf", but yes, right around the halfway point it picked up again. I appreciate the help getting the Tx switching fixed too!

Thx and 73






-------- Original message --------
From: "Evan Hand via groups.io" <elhandjr@...>
Date: 3/13/25 8:50 PM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3

Glad you fixed it!? The other pot is used to adjust the "bias" for the mixer:
?
?
?
The adjustment does not seem critical.? I would set it to the midpoint and verify that the receiver is sensitive and that the transmitted CW signal does not have spurs.
?
73
Evan
AC9TU

--
Mike - K8MCB?
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