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Ken Scharf ) writes:
xpyttl wrote: Jim Kortge, K8IQY, uses a cascode amp in his famous 2N2/40. He actually uses it in the transmitter ... even with a passive mixer you don't need a lot of gain on 40! See http://www.qsl.net/k8iqy .. There are two ways of looking at cascade, the devices are in series for dc and ac, or only ac. The above link shows the latter. I had an idea for a hybrid cascade amp of the first kind. The input would be a jfet which sorta becomes the emitter resistor for a bipolar transistor as the second stage of the cascade amp. The bipolar is run in grounded base (for ac, normal bias network and base bypassed to ground with a cap). Would give the advantages of high input impedance of the fet and high gain from the bipolar. It's been done. There was an article in Ham Radio magazine in 1970 or 1971 about a six meter converter. Just as you described, a common source JFET with a bipolar transistor as the upper element. Used a Vackar oscillator to make it tuneable. It might be this one: Six-meter converter, improved K1BQT 50 Aug 70 The date is about when I remember it, though I don't remember K1BQT being the author. Michael VE2BVW |
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