On 9/22/2015 12:43 PM, Art Snapper wrote:
I have another preamp that uses an old MRF-904. Have you characterized that
transistor at 1.8MHz? Is it worth replacing with a 2N5109?
Art
The MRF-904 in an antique microwave transistor. I can't
imagine why anyone would use that device at 1.8 MHz. Those
old transistors had a lot of base spreading resistance, often around 50
ohms. The 2N5109 is part of the 2N3866 family. What was special
about those devices was low base spreading resistance, maybe
5 ohms or so. This parameter, along with HF current gain, determines
NF. The big geometry should give better dynamic range and linearity.
Rick N6RK
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