In ,
(MaxGlc) wrote:

Hallo group.
I am
desperately looking for datasheet, documentation of MRF 477
transistor. I am working on amplifier which would replace it.
I almost finished but I still have some problems with impedance
match. My problem is simple: - i do not know the input imedance
the MRF has on 27Mhz frequency. I think in datasheet I could find
such information. I would appreciate any help.

Adam Chochla.


That datasheet is almost as rare as the transistor. Even if you find it, it
won't be much help. Series equivalent input impedance is dependent upon the
load, and while the datasheet may include a Smith chart for input impedance, it
will only be plotted for a specific load resistance, not a complex impedance as
will be the case in reality due to the high collector capacitance. You will have
to plug the transistor into a circuit and measure it.

And in case you don't have this info already:

Input power: 1.25 Watts
Output power: 40 Watts PEP/CW (10 Watts AM)
Power gain: 15 dB min.
Case: TO-220

I don't know what you intend to replace it with, but the Motorola's preferred
replacement is the MRF497 which is even more rare and expensive. You might
consider a matched pair of 2SC1945's in parallel if you can figure out how to
mount the second one without long leads.






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