No magic behind that. Any high current transistor will work.
I use BD250C as replacement.1$ transistor.
Mike
I use BD250C as replacement.1$ transistor.
Mike
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Palomar Maxi Mod
- Thread starter Low_Boy
- Start date
I don’t believe so. But it’s bigger so it’s better, the American way.
Also :
Muh temp readings
Muh research
Muh common sense
Also :
Muh temp readings
Muh research
Muh common sense
I spent a very large portion of my engineering career calculating "Junction Temperatures" and it had nothing to do with efficiency. If you exceed the maximum temperature you shorten the life expectancy of the transistor. https://en.wikipedia.org/wiki/Junction_temperature
The systems I worked on were supposed to last over 50,000 hours of continuous operation at 100 degrees centigrade.
Military Equipment power supplies. Everything was designed with a large safety area of operation.
If a component needed to conduct 20 amps a 40 amp part was used.( fuses and breakers not included)
Efficiency was calculated by power in divided by power out. We had another figure that we calculated which was "Power Density." Which is the power per cubic centimeter.
We had the highest power per cc of any manufacturer. We ran a frequencies higher than the others which had more benefits than I have the desire to explain here.
The systems I worked on were supposed to last over 50,000 hours of continuous operation at 100 degrees centigrade.
Military Equipment power supplies. Everything was designed with a large safety area of operation.
If a component needed to conduct 20 amps a 40 amp part was used.( fuses and breakers not included)
Efficiency was calculated by power in divided by power out. We had another figure that we calculated which was "Power Density." Which is the power per cubic centimeter.
We had the highest power per cc of any manufacturer. We ran a frequencies higher than the others which had more benefits than I have the desire to explain here.
Welcome back my friend.
You’ll probably get told how that military mess ain’t the same as these high powered, super engineered, critical down to the last drop, Pandora’s box 10 meter radios.
Just sayin.
You’ll probably get told how that military mess ain’t the same as these high powered, super engineered, critical down to the last drop, Pandora’s box 10 meter radios.
Just sayin.
I guess I'll just have to take them to school! Anybody who has never worked on military grade equipment does not have the leeway to comment. That's like living your life in a closed room with no windows and no electronic media and come out on your first day and telling the world how it needs to be run.
Well LC has made some fine points and dead-on balls accurate far as I’m concerned but it’ll be cross examined and said to be wrong. Mostly cause “muh thermocouple”.
We’ve all seen the video. It’s mostly wrong. It would be more bearable if not for that stupid music but at least the camera angle is good.
But hey, if you don’t peak and ruin your radio in the first place then how is that transistor and heat even an issue or concern? I’ve seen untouched radios 20+ years old that hasn’t had a failure of that part. Me thinks this part is on the list of “parts I will claim are failures” which is right above or below 13n10’s probably.
We’ve all seen the video. It’s mostly wrong. It would be more bearable if not for that stupid music but at least the camera angle is good.
But hey, if you don’t peak and ruin your radio in the first place then how is that transistor and heat even an issue or concern? I’ve seen untouched radios 20+ years old that hasn’t had a failure of that part. Me thinks this part is on the list of “parts I will claim are failures” which is right above or below 13n10’s probably.
Most of these super engineered radios have been pretty much been copied from other companies or previous designs. Even in high tech companies will reuse sections of their previous designs because they have been tested and work okay.
One company told me,"Do not reinvent the wheel because we have a design that works."
Many improvements were snubbed because they were different. It made no difference that the changes were minor and would improve performance and reliability. It was a family owned and staffed with family members.
I'm sure my comment under that YouTube video got deleted by Mark, but I explained why his "test" was useless. Sure, the Max-Mod heated up slower, but was that because it was creating less heat or because it was taking longer for the heat to transfer from the internal die to the outer mounting surface. He doesn't know and neither do we. Texas instruments have an app note that shows how these tests are done.
The part must be mounted to the heatsink with the same insulator, same paste, proper mounting screw torque, and with the probe passing through a small hole in the heatsink and then attached to the back of the transistor with thermal epoxy to ensure proper contact.
You'll also need at least one probe on the heatsink, a certain distance away from the transistor to determine whether it's the transistor or the heatsink that is limiting the cooling capability.
You also need 4 electrical probes.
The collector current and voltage drop across the collector-emitter junction must be set to identical values.
The base current and base-emitter voltage will be different due to DC gain variations between the devices and must be factored into the calculations. Higher gain usually means less base dissipation for the same collector current and thus less heat generated.
You use the electrical measurements to calculate how much power is being dissipated as heat in each device for the same collector current and voltage drop. This will tell you which transistor is more electrically efficient in this scenario. Hint: The one with least base dissipation.
Then, once you know how much heat energy is being lost/dissipated in the transistor die, you can use your temperature probe data to calculate how efficient the package is at getting that heat to the mounting surface, and how efficient your heatsink (and the transistor's connection to it) is at removing the heat from the mounting surface.
That "test" was just as useless as the one with the guy pointing the IR thermometer at a regulator. Sure, he did it all on camera, but the methodology was as non-scientific as it gets with no standards being measured and set between the two runs. Look, I've built many linear and switch-mode power supplies over the last decade, these tests aren't that complicated for a linear supply. I don't know which transistor is the best one, or the most efficient, and I truly don't care. What I do care about is the scientific methodology used for finding out which is better. Maybe the Max-Mod is the best out of the 3, maybe it's not, but if you're going to show a "test" and proclaim that one is better than the other, then I'd suggest sticking to the industry standard tests instead of just barking while claiming your useless test is better than everyone else's useless tests. You can't debunk other people's BS, with a different flavor of BS.
Sorry for the rant, but power supply nonsense gets me riled up. Mark's, "Who is the better tech," battle doesn't concern me, I have my own personal test bench. Lol.
On an additional note, the 2 finals aren't connected to the regulator, only the pre-driver and driver Mosfets are. The 2 finals are fed the full input voltage like any other linear PA section. Maybe if the manufacturers used smaller, more sensible drivers instead of having them the same as the finals, they wouldn't need such a large regulator. Ugh!
The part must be mounted to the heatsink with the same insulator, same paste, proper mounting screw torque, and with the probe passing through a small hole in the heatsink and then attached to the back of the transistor with thermal epoxy to ensure proper contact.
You'll also need at least one probe on the heatsink, a certain distance away from the transistor to determine whether it's the transistor or the heatsink that is limiting the cooling capability.
You also need 4 electrical probes.
The collector current and voltage drop across the collector-emitter junction must be set to identical values.
The base current and base-emitter voltage will be different due to DC gain variations between the devices and must be factored into the calculations. Higher gain usually means less base dissipation for the same collector current and thus less heat generated.
You use the electrical measurements to calculate how much power is being dissipated as heat in each device for the same collector current and voltage drop. This will tell you which transistor is more electrically efficient in this scenario. Hint: The one with least base dissipation.
Then, once you know how much heat energy is being lost/dissipated in the transistor die, you can use your temperature probe data to calculate how efficient the package is at getting that heat to the mounting surface, and how efficient your heatsink (and the transistor's connection to it) is at removing the heat from the mounting surface.
That "test" was just as useless as the one with the guy pointing the IR thermometer at a regulator. Sure, he did it all on camera, but the methodology was as non-scientific as it gets with no standards being measured and set between the two runs. Look, I've built many linear and switch-mode power supplies over the last decade, these tests aren't that complicated for a linear supply. I don't know which transistor is the best one, or the most efficient, and I truly don't care. What I do care about is the scientific methodology used for finding out which is better. Maybe the Max-Mod is the best out of the 3, maybe it's not, but if you're going to show a "test" and proclaim that one is better than the other, then I'd suggest sticking to the industry standard tests instead of just barking while claiming your useless test is better than everyone else's useless tests. You can't debunk other people's BS, with a different flavor of BS.
Sorry for the rant, but power supply nonsense gets me riled up. Mark's, "Who is the better tech," battle doesn't concern me, I have my own personal test bench. Lol.
On an additional note, the 2 finals aren't connected to the regulator, only the pre-driver and driver Mosfets are. The 2 finals are fed the full input voltage like any other linear PA section. Maybe if the manufacturers used smaller, more sensible drivers instead of having them the same as the finals, they wouldn't need such a large regulator. Ugh!
Good points and nice post but “muh tests” and “muh video”. It’s like whacking your finger with a hammer and saying it hurt but you keep doing it again. Some people don’t get it.
Yeah, among other things. I think questions like that are posed to generate views and attention mostly. Or you take one piece of information or one tiny fact that you like and play off that, it makes everything and everyone else invalid.
*yawn* gets boring after awhile...
But like I said, when you don’t get your mess peaked and ruined, how is heat even an issue anymore? And aren’t transistors supposed to get warm? Isn’t the purpose of a heatsink or object being used as such, supposed to get warm? Is heat not being transferred, heat?
If you have a 40 watt bulb and it gets hot, you swap to a 100 watt bulb and it gets hot as piss on desert pavement, isn’t that normal?
*yawn* gets boring after awhile...
But like I said, when you don’t get your mess peaked and ruined, how is heat even an issue anymore? And aren’t transistors supposed to get warm? Isn’t the purpose of a heatsink or object being used as such, supposed to get warm? Is heat not being transferred, heat?
If you have a 40 watt bulb and it gets hot, you swap to a 100 watt bulb and it gets hot as piss on desert pavement, isn’t that normal?
I think he will be showing his "Muh ignorance."
- No one is chatting at the moment.