Good morning,
I was absent from the forum during my vacation.
The number of topics on the Sbitx is impressive.
For an easier reading for those who are still at the Ubitx, wouldn¡¯t it be better to have a Sbitx group?
The moderator could create it and move all the Sbitx messages on it.
Have a great day.
Cdt
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Re: sBitx antenna-first warning
Bob, That's the plan for the weekend. A stockton bridge that is continously read by sbitx. If the swr is too high, it will reduce the power protecting the PA.
On Fri, Aug 5, 2022, 5:31 PM Bob Benedict, KD8CGH < rkayakr@...> wrote: Gordon's comments brings me full circle here. For tuning, reducing drive to limit power should be useful.
A "tune" button that lowers power temporarily for tuning, like that in every commercial rig I have ever owned,? could make that easy.
A bridge that feeds forward/reverse power info to the Pi would be a great addition and allow for the software to report SWR and protect the RF amp. Pi Picos are readily available for ~$5 which have 12 bit ADC and can do some local processing, then communicate to the Pi 4 by I2C. The Pico could even yank a Pi 4 GPIO? pin down to let an ISR immediately cut RF power if needed.
The Pico would be loafing along with this task and could easily do other low level tasks for the radio. Run the coffee maker?
--
? 73
??? Bob? KD8CGH
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Re: sBitx antenna-first warning
Gordon's comments brings me full circle here. For tuning, reducing drive to limit power should be useful.
A "tune" button that lowers power temporarily for tuning, like that in every commercial rig I have ever owned,? could make that easy.
A bridge that feeds forward/reverse power info to the Pi would be a great addition and allow for the software to report SWR and protect the RF amp. Pi Picos are readily available for ~$5 which have 12 bit ADC and can do some local processing, then communicate to the Pi 4 by I2C. The Pico could even yank a Pi 4 GPIO? pin down to let an ISR immediately cut RF power if needed.
The Pico would be loafing along with this task and could easily do other low level tasks for the radio. Run the coffee maker?
--
? 73
??? Bob? KD8CGH
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Re: Turn off WiFi on your sBitx
Have we made any progress on this noise?? I received my sBitx yesterday, and with the wifi enabled, its unusable due to the transient noises.? As mentioned earlier, adjusting the volume doesn't affect it, nor does having connected or disconnected to the antenna, or whether it's connected to a battery or a power supply.
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Re: sBitx antenna-first warning
Oh! ?I made a judgement with insufficient information. ?My wife says I do that often with her¡.. but she¡¯s been saying the same things for 50 years and I pretty much know where she is going. Someone famous once said ¡°Two ears. One tongue. ?Used best in that order.¡±
Dave K8WPE David J. Wilcox¡¯s iPad
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On Aug 5, 2022, at 6:28 AM, Scott KE8KYP <scott_massey@...> wrote:
?Hi David,
Thanks for the notes. ?I own and have used a 50 ohm dummy load for years. ?I was referring to Ashhar¡¯s comment that the three parallel 470¡¯s are to be connected to a SWR bridge. ?I too thought he was talking about a dummy load but he was talking about a SWR bridge circuit that uses three resistors. ?Sizing the resistors large enough help protect the PA finals during tuning operations.
There is always something to learn.
Cheers, Scott
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Re: sBitx antenna-first warning
I'd like to clarify : I have recommended a resistive swr bridge, not just three 470 ohms resistors. You will actually need 30 of them. Paralleling ten will produce a combined resistance of 47 ohms. Three such 47 ohm bundles will be used to make a resistive bridge. I will probably build one to show how it must be done. - f
Hi David,
Thanks for the notes.? I own and have used a 50 ohm dummy load for years.? I was referring to Ashhar¡¯s comment that the three parallel 470¡¯s are to be connected to a SWR bridge.? I too thought he was talking about a dummy load but he was talking about a SWR bridge circuit that uses three resistors.? Sizing the resistors large enough help protect the PA finals during tuning operations.
There is always something to learn.
Cheers, Scott
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sBitx, customs and management fees
Hello,
I just received my sBitx, Basic Kit. It has been accompanied by an additional payment of €53 VAT for the Treasury and €43 for DHL for customs management.
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So the radio has been a little more expensive than expected but I am sure it will be worth the extra cost and I will enjoy it a lot.
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Notice for European Union buyers!
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Ramon EA4GZI
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Re: sBitx antenna-first warning
Hi David,
Thanks for the notes. ?I own and have used a 50 ohm dummy load for years. ?I was referring to Ashhar¡¯s comment that the three parallel 470¡¯s are to be connected to a SWR bridge. ?I too thought he was talking about a dummy load but he was talking about a SWR bridge circuit that uses three resistors. ?Sizing the resistors large enough help protect the PA finals during tuning operations.
There is always something to learn.
Cheers, Scott
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Re: Ubitx ver 3 ssb transmit question
On receive I am seeing 160 ma minimum.? When I key the mike I can't get 100 ma with any adjustment on the two pots RV2 and RV3. It is 160 ma and above. I am seeing 630 ma on CW key down and 440 ma on SSB. RV1 has some effect but not a great deal. I have not checked RV1 resistance. I am using a charged 12v 7 ah battery for power.
I also did the calibration and BFO adjustment with WWV and the frequency looks good. Transmit audio sounds ok but I only can see 5 watts on the meter in CW. I have tried other microphones including an amplified one.
-John
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Re: The sBitx Release on www.vu2ese.com
Steve,
The sbitx software requires the presence of si5351 and wm8731 chips. It will crash without them. This is why the program is crashing. Try running it from command line. You will have to cd /home/pi/sbitx and then execute the program ./sbitx
Will the SBITX software start and run on a Pi 4, 8 GB by itself, in other words ?the Pi isn¡¯t connected to the SBITX boards? My kit has been shipped, but I thought I would familiarize myself with the SBITX software while I wait for it. I successfully burned the image from the website onto a 32 GB MicroSD card and the Pi 4 will boot from it. When I click on the SBITX icon, Fldigi starts in another browser tab and a window flashes briefly in the middle of the screen. I can open the Fldigi tab and close it, but I can¡¯t get the SBITX window to stay open. Thanks.
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Stephen, KO4CVU
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Re: The sBitx Release on www.vu2ese.com
Will the SBITX software start and run on a Pi 4, 8 GB by itself, in other words ?the Pi isn¡¯t connected to the SBITX boards? My kit has been shipped, but I thought I would familiarize myself with the SBITX software while I wait for it. I successfully burned the image from the vu2ese.com website onto a 32 GB MicroSD card and the Pi 4 will boot from it. When I click on the SBITX icon, Fldigi starts in another browser tab and a window flashes briefly in the middle of the screen. I can open the Fldigi tab and close it, but I can¡¯t get the SBITX window to stay open. Thanks.
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Stephen, KO4CVU
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Scott, I had posted in the linuxhams group that has members who develop the hamlib. The question was "what is the minimal set of commands that a net rigctl should implement?" So far I havent got any reply.? We should have a way where we kill the fldigi when we choose the digital mode.
These are tradeoffs, the fldigi takes time to wake up. So if it is not prelaunched, quickly flipping between modes will be difficult. On the other hand, fldigi automatically takes over and hangs onto the audio devices, preventing other apps to take over the same.
If there are any pulseaudio gurus here, we can perhaps do a better job with easier virtual devices. - f
Hi Ashhar,
I think I figured most of it out.? Only one external application can access audio at a time.? I did not notice that fldigi automatically launched when sBitx is launched.? I closed fldigi and launched wjstx and partial success.? CAT control is still funky, when it works it seems to only allow sbitx to external app control and not the other way round.? That worries me a bit for automated transmissions, etc., but I have a much better understanding of how audio is used in the RPI.? I'm going to download the RPI version of JS8Call and try to set it up like wjstx and fldigi.? We'll see.
So far I am really pleased.? Looking forward to updates and bug fixes as they become available.? I imagine you will have one for things like the audio "tap" and others in the near future.
Cheers, Scott?
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Hi Ashhar,
I think I figured most of it out.? Only one external application can access audio at a time.? I did not notice that fldigi automatically launched when sBitx is launched.? I closed fldigi and launched wjstx and partial success.? CAT control is still funky, when it works it seems to only allow sbitx to external app control and not the other way round.? That worries me a bit for automated transmissions, etc., but I have a much better understanding of how audio is used in the RPI.? I'm going to download the RPI version of JS8Call and try to set it up like wjstx and fldigi.? We'll see.
So far I am really pleased.? Looking forward to updates and bug fixes as they become available.? I imagine you will have one for things like the audio "tap" and others in the near future.
Cheers, Scott?
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Re: Turn off WiFi on your sBitx
OK. I was a little too fast. I did the test without the top cover. When the top cover is in place the sound is there but the frequency is lower than before.
When the WiFi signal is low the the WiFi -transmitter raises the signal power.
Tomorrow I will build another LM380 amplifier and try placing it away from the WiFi section.
/niels
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Re: sBitx antenna-first warning
Semiconductor devices die from either too much power leading to thermal damage, or higher voltage leading to voltage damage, or too much current leading to some other damage.?
It¡¯s not magical why they get destroyed. ?It¡¯s easy to explain why Q90 could be destroyed in earlier designs; too much reverse voltage.?
The impedance presented to the semiconductor devices by the combinations of passive devices between them and relatively free space (TraTransformers, inductors, capacitors, multiple multiple multiple) ?should remain relatively constant at any power level. ? The passive devices don¡¯t really care what power level (within their limits), they simply run around the Smith chart
Depending on what impedance they present to the RF power being potentially delivered by the semiconductors through drain voltage and current changes, some set of instantaneous voltages and currents (at radio frequency) will be developed. ? ??
At low power, the variations in the voltage and current Of the semiconductors ?is very much likely less. ?Hence, less ?chance of exceeding one of their ratings.?
I don¡¯t think the semiconductor die can tell what the SWR is¡ª only what voltage drops in current flows are happening. ?And from knowing where you are on the Smith chart those should be predictable. ??
I hope that makes some sense.?
Gordon.?
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On Aug 4, 2022, at 08:49, Jack, W8TEE via groups.io <jjpurdum@...> wrote:
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On Wednesday, August 3, 2022 at 01:45:51 PM EDT, Ashhar Farhan <farhanbox@...> wrote:
Jack, How much voltage were you running on the drains? - f
We've tested the T41 with its 510s to 40W and nothing fried. 80-40-20M all can deliver about 25W without much effort. 15M is about 20W and 10M drops to about 13W. Like I said, it is what it is...
Jack, W8TEE
On Wednesday, August 3, 2022 at 01:14:06 PM EDT, Jerry Gaffke via <jgaffke= [email protected]> wrote:
The IRF510 can work dependably, Allison reports years of success with HF amps at 40W push-pull, surviving everything from accidental open antenna connections to dead shorts. In posts to this forum from several years ago, Allison went into plenty of detail. She even used them on 6m at several hundred watts (with bunches of them in parallel). The QSX amp from qrp-labs uses IRF510's in push-pull, does a consistent 10W from 3 to 30mhz. ? Clean and linear even when operating from 12v, tolerates any antenna condition. A product of collaboration between Hans and Allison.? ?Cost of $26 USD for the kit, a steal. If I were building a rig like the sBitx from scratch, I would start with that amp for a PA, perhaps add PIN diode TR switching with the HV supplied by rectified RF. HFsignals could steal that PA design for the sBitx-v2, give Hans $5 for every unit if feeling guilty. Using the IRF510 for RF power amps takes careful design.? Especially heat sinking, as the IRF510 is not very good at getting heat from the die to the TO220 tab.? The IRF510 prefers more like 24vdc for higher power and reduced distortion. Improper design can blow the gate due to exceeding Vgs max spec momentarily Needs more drive than an RD16HHF1 to get similar power levels due to moderately high gate capacitance. However, Vds max is much higher for the IRF510 than it is for the RD16HHF1, so for cases of high Vds the IRF510 would survive a high SWR better than the RD16HHF1. Allison was of the opinion that moving to the RD16HHF1 on the uBitx would not help much. Reading from?? "The power amplifier of Figure 6 is a conventional power chain, probably a little sub-optimal. Two stages of pre-driver amplification with metal 2N2222As boost the signal level from -15 dBm to a little above 100 mW" For "sub-optimal" we could substitute "inexpensive".? One necessary change if wanting somewhat even power output all the way up to 30mhz would be an additional stage of amplification.? Gong from -15 dBm to +20 dBm (100mW) in two stages of 2N2222's is 35 dB of gain, or 17.5 dB per stage.? That's pushing it,? Though as we saw on the uBitx, optimizing a power amp is complicated, especially when doing it for a low budget product.? If NFET's seem too hard to use and just too dang complicated, an 807 or 6146 should do fine with any SWR when operating at 40W.? ?;-) Names could be shorter 80 years ago, they didn't have 10 gazillion different electronic parts to keep track of. Jerry, KE7ER On Wed, Aug 3, 2022 at 09:29 AM, Ashhar Farhan wrote:
The RD16HHF1s are no longer in production. There are some really good parts from Nexperia. They have no easy names like 807 or 6146. They have names like AFT05MP70. Why have short names when you can make up names that can't fit on the package?
- f
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Jack, W8TEE
-- Jack, W8TEE
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Re: QR code and KD8CEC Memory Manager, "Error- data file is short"
Hmmm. Strange. Worked for me last week and I have a badly messed up eeprom. I assume you entered your call sign in with the memory manager? The backup is stored by call sign.?
sorrry, no other suggestions. ?
73
Mark
AJ6CU
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Interesting.? When I adjust frequency at the wsjtx it changes on wsjtx screen but not the sBitx display.? However, when I change the frequency on the sbitx, it does change the wsjtx screen.? I can live with that but no audio makes it to the wsjtx program.? Hmm...
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I though the wsjtx was already configured to work with hamlib. The ft8 on the sbitx doesnt use the wsjtx. To use that, you have to set the mode to Digital (not ft8) and then use wsjtx through NET rigctrl of hamlib. Let me try it out here. - f
Hi Ashhar,
Just got my sBitx.? Awesome!? You deserve many "pats on the back" and profits.? Thank you for making such a nice product.
A few notes:
- Please program the tap to force volume control as discussed above.
- Native sBitx display on DS1 monitor is working great.? No need to move it to other display(s).
- Second (and/or third) monitor is scalable for third party applications.
- Consider providing Micro HDMI panel mount to right side above RPI penetrations.
Questions:
- I can't seem to get CAT control to work for WJSTX, WSPR mode.? Hamlib NET was programmed but not functional.? What should it be?
- What should the programming be for the Input and Output audio settings?
Maybe I am doing this all wrong so I will reread the Operating instructions but I am assuming that the external programs can work with sBitx and suppling WJST-X will work the radio but I must be missing something.
Again, thanks for a great design!
Cheers, Scott
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Re: sBitx PA Power Supply
The irfz24N cant run at a higher voltage. Nor is the PA power line isolated from the 12v supply line (unlike the ubitx)
Can the sBitx PA be run at a higher voltage like on the uBitx? If so, are there board connections for this? Or would it require major surgery on the PCB?
Thanks Max?
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Gerard
Bob Benedict, KD8CGH
David Wilcox K8WPE