On Mon, 14 Jun 2010 19:00:47 -0700 (PDT), walt wrote:

I'm hungering to learn of the setup and procedure you used, because
I'd like to know what reflection mechanism gave a return signal that
could be discriminated from the 70w output signal from the
transceiver.

Hi Walt,

For every hundred pundits there is at least one bench worker that is
more productive than them all. Of course I am being facetious, it is
probably closer to a thousand.

In the SARL Forums at:
http://www.sarl.org.za
search for the 19/04/2009 posting by ZS6BIM with the thread name:
Measuring the Output Impedance of a 100W Class AB HF Linear Amplifier
Plenty of data and charted and screen shots of O'scopes.

A very intriguing use of directional couplers (much as I would expect
Tom to have done). It seems to me I've directed you to similar work
(the rat-race-like method seems familiar to our email discussion some
dozen years ago).

The writer had the cojones to use his vector voltmeter at the
transmitter's antenna terminal. Back in 1997 I used my GR bridge to
look down the throat of the fire breathing dragon (TS430S) while it
was asleep and got similar results:
10 MHz 74 Ohms
14 MHz 74 Ohms
18 MHz 60 Ohms
21 MHz 37 Ohms
25 MHz 35 Ohms
28 MHz 48 Ohms
29 MHz 70 Ohms

73's
Richard Clark, KB7QHC