Ok, I need some help. Most know I deal with tubes and to me are a piece
of cake. I never did delve into the solid state stuff but was thinking
about hybrid combiners, etc. that I seen used on an amp and in the
Motorola RF Handbook. Specifically, application note: AN-749. I
understand how most of these work except I'm having some problem with
the resistance values for the 3-port hybrid arrangement. Now for
matching this into a 50 ohm line, I would think that this would use a
resistance of something in the order of 150 ohms on each leg so when it
was divided down three times, the amps would see 50 ohms if one set
failed. This app. note is kind of vague about its meaning but does
mention matching the amps to either 25 or 50 ohm lines. But, the
resistance they have listed is 22.2 or 16.6 and this is what confounds
me! Now 16.6 x 3 is 49.8 ohms but I thought the resistance went in the
other direction by multiplying it instead of dividing it? Plus, 22.2 x 3
is 66.6 ohms and where does this come from using either 25 or 50 ohm
line? The splitters/combiners I'm used to for two amps to match uses a
100 ohm resistance so it's 2 / 100 = 50 ohms impedance. Thats where I'm
coming up with the 150 for three which does not seem to be correct by
the book. Then after this combiner, it goes into a 3:1 transformer to
match it to a 50 ohm load. Now what am I missing here, I actually need
some help understanding this.
Will Matney
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