Walter Maxwell wrote:
The line impedance of either the input or load transmission line is irrelevant
to the basis for the Zo of the device, therefore a length of line is unnecessary
to establish a Zo environment, the current sample and voltage sample establish
it..

Walt, there's one thing I don't understand about what Dave reported.
As I understand it, these were the test setups.

TDR---50 ohm coax---MFJ---50 ohm coax---50 ohm load

The TDR doesn't see the MFJ wattmeter.

TDR---75 ohm coax---MFJ---75 ohm coax---75 ohm load

The TDR sees the MFJ wattmeter.

If the MFJ in the second setup were recalibrated for 75 ohms,
would the TDR not see it?

************************************************** **************

The threads for the past few days have all diverged from the
original question which was:

How long must the 50 ohm coax connected to the SWR meter be
for the SWR meter to report a valid SWR on that coax? The
answer obviously cannot be zero length.
--
73, Cecil http://www.qsl.net/w5dxp