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Re: Impedance matching for the audio stage


ajparent1/kb1gmx
 

THe most common is one of two... Transformer from 50 ohms to say 500-100 ohms to
match the base of a transistor. The problem with that is bandwidth as its a poor match
across the DC to many mghz of the DBM output. Another is hum pickup from magnetic fields.

The more common used in radio circuits is a common base amp with an emitter current of .5ma
which is about right for 50 ohms. This is the path that KK7B took and it offers both good voltage
gain and a good match to the dbm.

That is detailed in the book EMRFD, Experimental Design for RF Design, ARRL press.
Worth its weight and more.

Allison

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