"ralph sansbury" wrote in message
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"George Dishman" wrote in message
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"ralph sansbury" wrote in message
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I can understand the following:

Elsewhere you talk of a "sequence of voltages". If you stick
with that terminology which is entirely accurate, the
confusion won't arise.

Excellent. I'll try to remember to use that too.

I still dont understand what you mean by the multiplication
of voltages arriving at the two gates of dual gate transistor:

You produce the sum and difference frequencies by
making use of this identity:

sin(a) * cos(b) = [ sin(a+b) + sin(a-b) ] / 2

The right hand side contains the sum and difference
so is the output from the circuit. The function needed
on the right hand side is multiplication. The same
method works when using a wideband signal where each
component is shifted in frequency by the same amount.
The example I gave used the DSN bands but assumes it
is a single shift where in reality it is done in a
number of stages:

Suppose the signal is a band from 2265MHz to 2375MHz
and it is multiplied by a pure sine wave of 2000MHz.
The sum is a band from 4265MHz to 4375MHz while the
difference is a band from 265MHz to 375MHz.

My sense of this is that the sum of the voltages produces a pattern
which contains a frequency which is the difference frequency plus
the sum frequency plus the two input frequencies and that the
filters in the special circuits you refer to produce these
separate components???.

If you replace "the sum of the voltages" in the first
line by "the product of the voltages", the paragraph
is perfectly correct. The filters are conceptually
separate from the mixer but often merged in practice.

George