Hi. I am looking for 28 volts pills. What number should they be ? I am planing to replace my 4 pills 2SC2879 for ones rated at 28 volts. Any suggestions ?
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28 volts pills
- Thread starter Alexis Mercado
- Start date
MRF421 is probably as close as you'll get. Bear in mind that you'll only obtain rated power at the supply voltage listed. Running a 28 Volt transistor at 12 Volts will reduce the power it can deliver.
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I think you meant MRF422, Nomad.
Toshiba used to make the 2SC2510 (150W PEP) that was the 28 volt version of the 2SC2879 (100W PEP)
HG is now making the 2SC2510.
Toshiba used to make the 2SC2510 (150W PEP) that was the 28 volt version of the 2SC2879 (100W PEP)
HG is now making the 2SC2510.
What are you trying to do or hoping to accomplish with this?
If you are going to apply 28 volts, without increasing the impedance in the output section, you are going to blow those transistors up, long before it makes the output it did when it was stock. The output impedance should be double what it is on 12 volts, to make the same output on 28 volts. Forcing the output into an impedance that is half of what it should be, will exceed current and dissipation ratings, very quickly!
I’ll take the amp to an amplifier builder. He will do some changes to accomplish what you are telling me.
If we just consider input power for simplicity, it only takes half the current, at double the voltage, to produce the same power. Half of the current, means that the output load impedance, is now....
Well, as I think about this more, for current to drop in half with a doubling of voltage, impedance must go up by 4 times. You are correct Nomad. Thanks for pointing this out.
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That's probably a good idea. They will probably tell you what your wanting to have done is a bad idea. A 4 pill amplifier with 2879 finals will work just fine in a semi truck run off the trucks 13.8-14.6 volts.
MRF422. I have an amp that was designed for 2SC2879 and changed to MRF422.
The OP's plan did not sound impossible. Zetagi makes a line of MRF422 amps with no unusual looking OP Transformers. Raising the impedance of the OP Transformer requires altering the turns and perhaps the cores as well.
Problems would be worse below 40 meters.
What about the Input Transformer?
Problems would be worse below 40 meters.
What about the Input Transformer?
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I have not had the amp I was speaking of, on the air in quite a few years. I just acquired a pile of power supplies, that I need to build up to run this amp. Unfortunately, I used rivets to close the cabinet. I was planning to drill them out anyway. When I do, I can take a photo of the modules with both 2879 and MRF422, as I have a similar 8x2879 amp that was gutted as a parts donor for a 8x MRF422.