On Mar 22, 12:31 pm, (Richard Harrison)
wrote:

What is the generator load that extracts maximum power from a
transmitter? A conjugately matched load, of course. To determine the
impedance of a transmitter, one only needs to find the load which
extracts maximum power. The transmitter impedance is its conjugate.

Best regards, Richard Harrison, KB5WZI

We have a new signal generator here at the Labs, but it came without
any documentation. We've been hoping to find out more about it, and
your suggestion gave us a clue for a test to try. We have a limited
set of loads, only from 40 to 60 ohms, but we can add some known
reactance in series with that. When we put an accurate 50 ohm load on
the generator, we measured exactly 1 watt with our accurate RF power
meter. When we changed the load to 40 ohms, the power went up to
1.238 watts, and with a 60 ohm load, it was .839 watts. When we add
reactance, either capacitive or inductive, the power goes down, so
we're pretty sure the generator output doesn't look reactive. Beaker
is having a little trouble with the math on this one. Could you help
him out? What sort of output impedance does this generator have?

Oh, and we thought to do another experiment. While the generator was
operating, we sent a short burst of RF down a 50 ohm transmission line
to the generator's output. Because the power measurements seem to say
the generator's output resistance is very low, we thought we would see
a return pulse, delayed by the round-trip time down the 15 meters of
high-quality cable. But we didn't see any echo. What could be going
on? We double-checked everything, and even looked into the line next
to the generator with a high impedance probe. We can see the burst
going in there, but still nothing comes back.

From the labs,
Dr. Honeydew