Zetagi B550p what transistors....

[bigpimp347]

ok it lasted a whole day before it went BOOOOOOM..!!!!
seems three of the four have gone down..
although i had two fans on it and ran it on number 5 with around 10w drive this gave me around 180w on FM..

these things are not capable of a good chat session..!!

so..
what to install...

comes with MRF455 as standard..some have SD1446 which are slightly more power..
but i'm thinking a different change..
what about 2SC2290 or even better the cheap readily available 2SC2879 ??
most amp builders are using 2879 as these are 100w pep and are cheap as chips to buy.
so straight swap out ??
power to be expected from the amp ?? i was thinking around 400w pep, so on FM i may get around 250/300w..

as all transistors seem to fall within spec needed i'm assuming a straight swap would work..

[RD250]

I don't know all the Zetagi model types but usually these are marketed as an AM/SSB amplifier. It won't have been designed for heavy duty FM use.

I'd imagine it's designed to produce about 240W PEP on SSB and 60W AM carrier (240WPEP when modulated)

So running it at 180W on FM for long chats is bound to stress it.

I'm not sure swapping out for the other parts is going to make a huge difference in terms of power output or reliability but maybe someone has tried it.

However, the power output into a 50R load is mainly dictated by the output transformer ratios and the power supply voltage (13.8V?) so even if you swap for high power parts the output power won't go up accordingly.

i was thinking around 400w pep, so on FM i may get around 250/300w

400W PEP? Not a chance if you just swapped the transistors. Although somebody, somewhere will have a cheapo ham/cb power meter that will say otherwise