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I just realized that the MRF454 has a collector - emitter breakdown voltage of 25 volts! With 7 more volts of "headroom" than the 2SC2879, no wonder the MRF454 is so rugged. Even the dissipation is the same 250 watts that the 2SC2879 has. The only weak link with the MRF454 is the 20 amp collector current, being 5 amps less. Therein lies the key to your statement regarding "in the right circuit".

Isn't it ironic how the best RF transistor you could buy 35 years ago, is also the best one to still survive and be in production today? In the mid 1980's, most of the biggest HF solid state amps were using the MRF454. Several years later when the Toshiba hit the market, it really didn't take too much work to get those old circuits to match up with the new part.

Therefore, it would be very easy to go back one step and rework 2SC2879 amplifiers, to increase their input and output impedances to once again, match the MRF454. This makes me wonder if there is not a market to replace the 4 junk, TO-220 transistors we see in high power exports, with a matched pair of MRF454's? I can't imagine it would be too hard to fit them on the board, rewrap the input and output transformers and then scrub off 75% of the bias voltage with a 4:1 resistor divider...

<blockquote data-quote="Shockwave" data-source="post: 757718" data-attributes="member: 10882">I just realized that the MRF454 has a collector - emitter breakdown voltage of 25 volts! With 7 more volts of &quot;headroom&quot; than the 2SC2879, no wonder the MRF454 is so rugged. Even the dissipation is the same 250 watts that the 2SC2879 has. The only weak link with the MRF454 is the 20 amp collector current, being 5 amps less. Therein lies the key to your statement regarding &quot;in the right circuit&quot;.Isn&#039;t it ironic how the best RF transistor you could buy 35 years ago, is also the best one to still survive and be in production today? In the mid 1980&#039;s, most of the biggest HF solid state amps were using the MRF454. Several years later when the Toshiba hit the market, it really didn&#039;t take too much work to get those old circuits to match up with the new part.Therefore, it would be very easy to go back one step and rework 2SC2879 amplifiers, to increase their input and output impedances to once again, match the MRF454. This makes me wonder if there is not a market to replace the 4 junk, TO-220 transistors we see in high power exports, with a matched pair of MRF454&#039;s? I can&#039;t imagine it would be too hard to fit them on the board, rewrap the input and output transformers and then scrub off 75% of the bias voltage with a 4:1 resistor divider...</blockquote>

[QUOTE="Shockwave, post: 757718, member: 10882"] I just realized that the MRF454 has a collector - emitter breakdown voltage of 25 volts! With 7 more volts of "headroom" than the 2SC2879, no wonder the MRF454 is so rugged. Even the dissipation is the same 250 watts that the 2SC2879 has. The only weak link with the MRF454 is the 20 amp collector current, being 5 amps less. Therein lies the key to your statement regarding "in the right circuit". Isn't it ironic how the best RF transistor you could buy 35 years ago, is also the best one to still survive and be in production today? In the mid 1980's, most of the biggest HF solid state amps were using the MRF454. Several years later when the Toshiba hit the market, it really didn't take too much work to get those old circuits to match up with the new part. Therefore, it would be very easy to go back one step and rework 2SC2879 amplifiers, to increase their input and output impedances to once again, match the MRF454. This makes me wonder if there is not a market to replace the 4 junk, TO-220 transistors we see in high power exports, with a matched pair of MRF454's? I can't imagine it would be too hard to fit them on the board, rewrap the input and output transformers and then scrub off 75% of the bias voltage with a 4:1 resistor divider... [/QUOTE]

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