So, after the diagnosis and repair of the power group components, Q9,Q10,Q101,R5,R6 (all replaced), on power up, +12v drops to under 2v and the area around the Q12-15 group heats up quickly. I did note that D7 was basically shot, continuity in both directions. What are my most likely culprits at this point?
Getting back to the SMS 5V regulator noise, I just finished building a QRPlabs QMX+ and while it uses 3 different SMS regs it does not exhibit any noise from them because of this, direct quote from QMX+ info:
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" The rather unique aspect is that the microcontroller knows the radio's operating frequency; it also knows the switching frequency. Both are known relative to the high precision 25MHz TCXO reference which is the master clock for the entire design. The CPU can calculate where the harmonics of the switching frequency occur and slightly alter the buck converter PWM frequency to move the interference far away from the operating frequency."
Version 4.4 introduces new features, enhancements, and fixes to improve your experience.
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Here’s what’s new:
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New Features:
Added power down button from sbitx menu 2
Added Macro chooser button in the main GUI for FT8/CW modes
Added full spectrum/waterfall button for CW modes
Added current/voltage meter display functionality for INA260 Power Sensor add-on hardware
Added max-hold visualization for POWER and corrected SWR calculation in the case of little or no FWD POWER
Added AUTOSCOPE in MENU 2 which adjusts the vertical offset of the scope and the base value for the waterfall automatically, making it easier to see signals clearly.
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Fixes and Improvements:
Fixed the Macro change screen refresh when changing macros
Fixed the CW Macro issue when the delay/WPM were set at a threshold
Adjusted CW shaping timing and reduced from 20ms to 4ms for improved CW transmission
Fixed the "crashing" noise in voice, FT8, and DIGI modes
Please see the release notes at ?for more information.
Je to dobrá zpráva pro v?echny ?ekající. Není pot?eba kolektiv HF Signals nutit ke spěchu. Dělají, co mohou aby v?e bylo v po?ádku a osazení desek, kompletace a testování se nedají nijak uspěchat bez zhor?ení kvality. Proto na ně netla?me a ?ekejme, na v?echny se dostane. Snad by mezitím mohl b?t ke sta?ení nějak? manuál nebo instruktá?ní video, jak TRX správně nakonfigurovat nebo provozovat. Také se sice nemohu do?kat ur?itě v?borného TRXu, kter? je brzy na cestě k nám. Lev OK2PLL
Lev, ?Neváhejte pou?ít P?eklada? Google, proto?e jazyk pou?ívan? na fóru je angli?tina. U?ivatelé nebudou kv?li va?emu rozmaru hledat p?ekladatele, ale va?i zprávu budou ignorovat.
?
Lev, feel free to use google translate because the language used by the forum is English. Users will not look for a translator because of your whim, but will ignore your message.
Well, let's wait with celebrating until I replace the MOSFETs and find the device working properly.?
What annoys me is that I didn't detect that parasitic "diode" between gate and source at the first measurements after disassembling the transceiver. However, maybe the damage was increasing while I tested it.
73,
Wojtek?
sob., 1 mar 2025, 12:40 u?ytkownik Gordon Gibby KX4Z via <docvacuumtubes=[email protected]> napisa?:
Delighted that you found the problem. Interesting that both drains showed an AC voltage even though one device was effectively shorted.? That is surprising to me.
Wish you the best
Gordon kx4z?
On Mar 1, 2025, at 06:38, HA3HZ via <gyula=[email protected]> wrote:
?
Wojtek,
Buy 10 pieces so that you can choose the two with almost the same opening voltage.
They may be the same in shipping, but there is still a difference between them.
You can install them without Aluminum nitride with the old mica, and use some kind of fan to cool the heat sink from the back.
Read another message where I wrote how I use the v2.
You can easily replace the AlN ceramic later if you look at which screw you need to unscrew to remove the heat sink.
Read and do the Bias adjustment as described here (you can also find the article on ).
?
It is important to do the adjustment with a 2A current limit!
Try adding noaudio to the vc4-hdmi (not sure this is the correct name) line in the config.txt file in /boot.? I had to do that for an external HDMI monitor with audio.
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I still need to shut down and wait to restart my DE.??
?
I also suggest going to JJ's 64-bit software.? My DE seems to like it better.
On my SECOND sBitx (which I bought used, once again) here are the items I plan to do (I prefer the V2 model, just because it offers me a bit more "headroom" for digital etc on the lower bands -- I think Ashhar made the right choice for the mass production with the changes he made fir the V3)
1.? A few added resistors:? ?/g/BITX20/wiki/36110? ? That will eliminat?a couple of known traps
2.? Change the insulators to Aluminum Nitride and slightly polish the heatsink
3.? I'm debating with myself whether to change the output MOSFETS to IRF520.? ? It is slightly tricky mechanically, but the V2 I purchased has the better securement for the bar, which makes it less tricky (and is probably on all of the current V3s)? ? So I may go ahead and switch out.
4.? I like the TVS diode protection, so I'll add those back in.? ?On the V2 this requires scraping a few leads of their protective coverage and then carefully soldering these incredibly tiny devices.? ??
Either use my own modified software or the recent 64-bit software from JJ that greatly improves the sampling of the CW system and also the T/R delays.? ?I have just installed the 64-bit software and operating system on that particular unit, and was very happy to see it work fine with the upgraded software.? ? Haven't learned how to compile yet, but that will come.? ?This is a radio for tinkerers like me!?
Additions:? (These aren't protections, they are just things that I happen?to like)
A.? ?I will probably put in the output optocoupler SEND output that I came up with, because I still have parts and this is helpful to me in controlling a linear amp or a transverter.
B.? Since I do a bunch of digital that works better with a Windows PC, I'll probably add back in the secparate?audio output independent of the one for headphones etc.? ??
I do SSB, digital and a good bit of CW.? ?You just can't get this same level of FUN on CWwith my Icom 7300.
I like having everything assembled into a "go box"? ? I don't go hiking, I just drive up to places and pull out the simple plywood "go box" -- it has everything I need, including antenna tuner, power supply, and sometimes even a built-in CW paddle!? ? That's just my preference; others do their own thing!
Part of the joy of ham radio (as opposed to FRS/GMRS / CB / cell phones ) is our ability to tinker and improve?
On Sat, Mar 1, 2025 at 7:18?AM Gordon Gibby KX4Z via <docvacuumtubes=[email protected]> wrote:
This radio is ground-breaking in that it is NOT a $1200 Icom and Yaesu and yet it has many of their features, and sometimes does things far more expensive radios cannot.? ? Instead of using $15 final amplifier MOSFETS (which would be much easier to design for!) it uses $1 MOSFETS.
The ICOM 718 went through at least THREE different designs for it output power stage over its course of years (and possibly more).? ?I have worked on one with bipolar transitors and another with mosfets!? ?Wonder if their owners even knew?
The VHF parasitic oscillation caused a lot of problems, and required redesign of the T/R system as part of the eradication.? ?That resulted in an elegant diode-switching system (where Hans is said to have helped out greatly) and that made this an even better radio.? ??
I think there are still a few "gotchas" in the diodes connected to?+12 without series limiting resistors -- but if you never venture in there with a probe, they will do just fine.? ? Many of us prefer to change out the mica insulators to Aluminum nitride and at the same time, polish the matching surface of the heatsink.? ??
I remember when some of the most expensive radios on the market were found to have huge linearity issues -- very embarrasing?-- and the company came up with fixes eventually and solved it.? ?
The use of a LINUX COMPUTER as the controlling microcomputer is new and different for many of us, and that has both advantages and disadvantages.? ?
I can't remember if the software includes "foldback" on the power but if it doesn't, that could easily be added.? ?What I think we've generally realized is that on a 12V supply, going to 100V MOSFETS gives a great level of protection against poor SWR.? ? The GATE was another weak spot and in recent designs, Ashhar has chosen to adjust the gain around to reduce that risk, and he has also in some cases added TVS protection diodes.? ? ??
There is a little 3-mosfet power switcher that we think has a "gotcha" built into it that can be fixed by adding one resistor and for the adept, that is a good idea.? ?
Past that, it is an incredibly fun radio!? ?And cheap enough that I can own TWO of them!? ? It got me onto 2-meter SSB for the very first time (with the addition of a transverter) and the ability of the microcontroller to run other software at the same time is helping me begin to forage into satellite communications, something I've never done before.? ??
It is NOT the radio for "appliance operators"? who are better off teething on ICOM or YAESU (I prefer Icom).? ?There are all kinds of people in ham radio and not every radio fits every person, at every stage of their growth!
What a fun radio!
73
Gordon KX4Z
On Sat, Mar 1, 2025 at 7:05?AM Evan Hand via <elhandjr=[email protected]> wrote:
Hi Gyula,
?
I remember reading about a failed DE output transformer. The stacked toroids cracked due to heat, leading to the V2 and V3 redesign.
This radio is ground-breaking in that it is NOT a $1200 Icom and Yaesu and yet it has many of their features, and sometimes does things far more expensive radios cannot.? ? Instead of using $15 final amplifier MOSFETS (which would be much easier to design for!) it uses $1 MOSFETS.
The ICOM 718 went through at least THREE different designs for it output power stage over its course of years (and possibly more).? ?I have worked on one with bipolar transitors and another with mosfets!? ?Wonder if their owners even knew?
The VHF parasitic oscillation caused a lot of problems, and required redesign of the T/R system as part of the eradication.? ?That resulted in an elegant diode-switching system (where Hans is said to have helped out greatly) and that made this an even better radio.? ??
I think there are still a few "gotchas" in the diodes connected to?+12 without series limiting resistors -- but if you never venture in there with a probe, they will do just fine.? ? Many of us prefer to change out the mica insulators to Aluminum nitride and at the same time, polish the matching surface of the heatsink.? ??
I remember when some of the most expensive radios on the market were found to have huge linearity issues -- very embarrasing?-- and the company came up with fixes eventually and solved it.? ?
The use of a LINUX COMPUTER as the controlling microcomputer is new and different for many of us, and that has both advantages and disadvantages.? ?
I can't remember if the software includes "foldback" on the power but if it doesn't, that could easily be added.? ?What I think we've generally realized is that on a 12V supply, going to 100V MOSFETS gives a great level of protection against poor SWR.? ? The GATE was another weak spot and in recent designs, Ashhar has chosen to adjust the gain around to reduce that risk, and he has also in some cases added TVS protection diodes.? ? ??
There is a little 3-mosfet power switcher that we think has a "gotcha" built into it that can be fixed by adding one resistor and for the adept, that is a good idea.? ?
Past that, it is an incredibly fun radio!? ?And cheap enough that I can own TWO of them!? ? It got me onto 2-meter SSB for the very first time (with the addition of a transverter) and the ability of the microcontroller to run other software at the same time is helping me begin to forage into satellite communications, something I've never done before.? ??
It is NOT the radio for "appliance operators"? who are better off teething on ICOM or YAESU (I prefer Icom).? ?There are all kinds of people in ham radio and not every radio fits every person, at every stage of their growth!
Je to dobrá zpráva pro v?echny ?ekající. Není pot?eba kolektiv HF Signals nutit ke spěchu. Dělají, co mohou aby v?e bylo v po?ádku a osazení desek, kompletace a testování se nedají nijak uspěchat bez zhor?ení kvality. Proto na ně netla?me a ?ekejme, na v?echny se dostane. Snad by mezitím mohl b?t ke sta?ení nějak? manuál nebo instruktá?ní video, jak TRX správně nakonfigurovat nebo provozovat. Také se sice nemohu do?kat ur?itě v?borného TRXu, kter? je brzy na cestě k nám. Lev OK2PLL
Lev, ?Neváhejte pou?ít P?eklada? Google, proto?e jazyk pou?ívan? na fóru je angli?tina. U?ivatelé nebudou kv?li va?emu rozmaru hledat p?ekladatele, ale va?i zprávu budou ignorovat.
?
Lev, feel free to use google translate because the language used by the forum is English. Users will not look for a translator because of your whim, but will ignore your message.
Bravo Delta, I've read almost every message since the summer of 2022, but I don't remember a melted transformer. Could you give me a link to what I missed. If you read my post today about v2, then I don't need to write more. Use a current-limiting power supply and an antenna that is tuned to the frequency and you will have few problems. Another important thing is the quality of the mechanical and electrical connections. The components go through a lot of checks during production, but despite this, failures can occur.
The last time I opened the device was to replace the CR2032, because the date display went crazy.
Delighted that you found the problem. Interesting that both drains showed an AC voltage even though one device was effectively shorted. ?That is surprising to me.
Is it because people are experimenting more with sBITX that we are seeing more failures?
Does it have automatic output reduction in case of High SWR as in case of regular commercial SDR?
Disclaimer: I am not a BITX user. Joined the group to learn more about them as many in this region use it. In fact it was not available for purchase when I had no radio and was looking for it!
Joel Caulkins/N6ALT
Lev
HA3HZ
WK4DS