On Mar 1, 2025, at 19:13, WZab - SP5DAA via groups.io <wzab01@...> wrote:
?
Yes! Replacing the MOSFETs fixed my sBitx v3.
So I have learned two lessons:
Running continuously in FT8 mode requires either reducing DRIVE or using a fan to improve cooling MOSFETs (especially if running at 13,8V power supply voltage).
MOSFETs failure due to overheat do not necessarily cause shorting drain to source.
Thanks a lot to all who helped me to isolate and fix the problem.
Yep, at least I had a bit of foresight and ordered a few more pairs of IRF510s. I'm going to pick it up again tomorrow. I've found that in cases like this, more than a few hours and I start to get frustrated and more likely to cause myself more
problems!
So typically what you do there is unsolder the drain on each MOSFET and just disconnect it so that you can stop those from potentially taking all the current and then see if you still have the direct short
You have to keep working at it until you find out where the current is going, slick tricks like looking for which traces are hot or which voltages are low might help
On Mar 1, 2025, at 18:43, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:
?
On Mar 1, 2025, at 18:38, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:
?Well, the reverse voltage or whatever happened might have fried the MOSFETS?
On Mar 1, 2025, at 18:27, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, so I've removed D7, I have a direct short to ground, somewhere. I haven't even thought of plugging a pi into it since this began. Right now, even if I apply only 2-3v, the fat trace running from the main switch then around the edge of the board to the
PA xformer is VERY hot. I don't have a component tester at the moment, to examine whats going on with the individual transistors. Any suggestions are welcome.
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern
Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY
LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was
damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else
see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
Let usknow?how it goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via
<mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of
the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
Running continuously in FT8 mode requires either reducing DRIVE or using a fan to improve cooling MOSFETs (especially if running at 13,8V power supply voltage).
MOSFETs failure due to overheat do not necessarily cause shorting drain to source.
Thanks a lot to all who helped me to isolate and fix the problem.
So typically what you do there is unsolder the drain on each MOSFET and just disconnect it so that you can stop those from potentially taking all the current and then see if you still have the direct short
You have to keep working at it until you find out where the current is going, slick tricks like looking for which traces are hot or which voltages are low might help
On Mar 1, 2025, at 18:43, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:
?
On Mar 1, 2025, at 18:38, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:
?Well, the reverse voltage or whatever happened might have fried the MOSFETS?
On Mar 1, 2025, at 18:27, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, so I've removed D7, I have a direct short to ground, somewhere. I haven't even thought of plugging a pi into it since this began. Right now, even if I apply only 2-3v, the fat trace running from the main switch then around the edge of the board to the
PA xformer is VERY hot. I don't have a component tester at the moment, to examine whats going on with the individual transistors. Any suggestions are welcome.
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern
Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY
LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was
damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else
see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
Let usknow?how it goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via
<mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of
the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
On Mar 1, 2025, at 18:38, Gordon Gibby KX4Z via groups.io <docvacuumtubes@...> wrote:
?Well, the reverse voltage or whatever happened might have fried the MOSFETS?
On Mar 1, 2025, at 18:27, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, so I've removed D7, I have a direct short to ground, somewhere. I haven't even thought of plugging a pi into it since this began. Right now, even if I apply only 2-3v, the fat trace running from the main switch then around the edge of the board to the
PA xformer is VERY hot. I don't have a component tester at the moment, to examine whats going on with the individual transistors. Any suggestions are welcome.
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern
Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY
LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was
damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else
see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
Let usknow?how it goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via
<mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of
the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
On Mar 1, 2025, at 18:27, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, so I've removed D7, I have a direct short to ground, somewhere. I haven't even thought of plugging a pi into it since this began. Right now, even if I apply only 2-3v, the fat trace running from the main switch then around the edge of the board to the
PA xformer is VERY hot. I don't have a component tester at the moment, to examine whats going on with the individual transistors. Any suggestions are welcome.
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern
Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY
LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was
damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else
see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
Let usknow?how it goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via
<mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of
the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
On Mar 1, 2025, at 18:27, Michael Bales via groups.io <mikebales73@...> wrote:
?
Yes, so I've removed D7, I have a direct short to ground, somewhere. I haven't even thought of plugging a pi into it since this began. Right now, even if I apply only 2-3v, the fat trace running from the main switch then around the edge of the board to the
PA xformer is VERY hot. I don't have a component tester at the moment, to examine whats going on with the individual transistors. Any suggestions are welcome.
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern
Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY
LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was
damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else
see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
Let usknow?how it goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via
<mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of
the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
Yes, so I've removed D7, I have a direct short to ground, somewhere. I haven't even thought of plugging a pi into it since this began. Right now, even if I apply only 2-3v, the fat trace running from the main switch then around the edge of the board to the
PA xformer is VERY hot. I don't have a component tester at the moment, to examine whats going on with the individual transistors. Any suggestions are welcome.
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern
Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY
LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was
damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else
see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
Let usknow?how it goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via
<mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of
the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
If you have a
current limited supply at about 2Amps
OR?
a variable voltage
supply,
Then you could do a
preliminary test after replacing D7 so you again have SOME
reverse polarity protection.? ?We have had MULTIPLE radios
severely damaged by good friends of mine in Northern Florida
by accidentally getting the polarity backwards.? ?It only
takes a blink of an eye.
I use a "wall wart"
that ONLY puts out 12V and can't put out more than 1-2Amps for
initial?testing of some of my radios.
Alternatively, I
have a MFJ power supply that is adjustable.? ??
With the Raspberry
Pi DISCONNECTED, you?can very carefully apply current limited
source, or else use a variable voltage source of about 5V and
see what current flows -- there should?be VERY LITTLE if the
raspberry isn't connected.? ? Then if you can get the voltage
up to 12V without having current more than 1/2 amp or so --
you might be in OK shape.? ? But at that point I would
carefully measure the output of the 5V regulator and see if it
was damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky,
not all the 2n2219s were damaged.? ?By measuring the voltage
across their emitter resistors you can calculate the current
through them annd?see what is happening, or else see which
ones are getting HOT.? ??
On Amazon, there are
multiple sources for 2219a's and they aren't that
expensive.....
One of the things I
try to always put together now,....is some form of
polarit?protection on anything expesnsive that I buy.? ? ?I
built a mosfet protection circuit and did a printed circuit
board which is shared as a project on ?
? Lots in our group have used it.? ? I put it on EVERY radio
down at our EOC becuase?it is SO EASY to damage radios when
people are stressed out or tired.
Let usknow?how it
goes!
Gordon KX4Z
On Sat, Mar 1, 2025 at 5:33?PM
Michael Bales via <mikebales73=[email protected]>
wrote:
Not sure, I must have inadvertently applied
12v somewhere I shouldn't have. Either way, I doubt that I
can check any further damage until I replace D7. Probable
worst case would be having to drop $40 on new 2n2219s.
Michael,
how did D7 get damaged?? ?Was reverse polarity applied
to the radio at some point?? ?that would be the most
likely way to damage D7 and it would have serious
impacts on some of the other components, such as the 4
transistors in the driver section.? ?So what do you
know about how D7 got damaged???? it isthere?to
protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at
3:01?PM Michael Bales via
<mikebales73=[email protected]>
wrote:
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?
If you have a current limited supply at about 2Amps
OR?
a variable voltage supply,
Then you could do a preliminary test after replacing D7 so you again have SOME reverse polarity protection.? ?We have had MULTIPLE radios severely damaged by good friends of mine in Northern Florida by accidentally getting the polarity backwards.? ?It only takes a blink of an eye.
I use a "wall wart" that ONLY puts out 12V and can't put out more than 1-2Amps for initial?testing of some of my radios.
Alternatively, I have a MFJ power supply that is adjustable.? ??
With the Raspberry Pi DISCONNECTED, you?can very carefully apply current limited source, or else use a variable voltage source of about 5V and see what current flows -- there should?be VERY LITTLE if the raspberry isn't connected.? ? Then if you can get the voltage up to 12V without having current more than 1/2 amp or so -- you might be in OK shape.? ? But at that point I would carefully measure the output of the 5V regulator and see if it was damaged BEFORE CONNECTING ANY RASPBERY?TO IT.
If you are lucky, not all the 2n2219s were damaged.? ?By measuring the voltage across their emitter resistors you can calculate the current through them annd?see what is happening, or else see which ones are getting HOT.? ??
On Amazon, there are multiple sources for 2219a's and they aren't that expensive.....
One of the things I try to always put together now,....is some form of polarit?protection on anything expesnsive that I buy.? ? ?I built a mosfet protection circuit and did a printed circuit board which is shared as a project on ? ? Lots in our group have used it.? ? I put it on EVERY radio down at our EOC becuase?it is SO EASY to damage radios when people are stressed out or tired.
On Sat, Mar 1, 2025 at 5:33?PM Michael Bales via <mikebales73=[email protected]> wrote:
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of the
other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
Not sure, I must have inadvertently applied 12v somewhere I shouldn't have. Either way, I doubt that I can check any further damage until I replace D7. Probable worst case would be having to drop $40 on new 2n2219s.
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of the
other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
Gordon?
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via
<mikebales73=[email protected]> wrote:
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?
Michael, how did D7 get damaged?? ?Was reverse polarity applied to the radio at some point?? ?that would be the most likely way to damage D7 and it would have serious impacts on some of the other components, such as the 4 transistors in the driver section.? ?So what do you know about how D7 got damaged???? it isthere?to protect somewhat against?reverse polarity
On Sat, Mar 1, 2025 at 3:01?PM Michael Bales via <mikebales73=[email protected]> wrote:
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?
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:
?
" 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.
?
Here’s what’s new:
?
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.
?
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!
Kevin
Joel Caulkins/N6ALT
Lev