"Cecil Moore" wrote in message
...
Dave wrote:
obviously at 1/4 wave from the load the impedance seen by the bird is not
50 ohms.

That's the whole point, Dave. The poor ignorant Bird doesn't know what
is going on external to itself. You and I have to be smarter than the
Bird and not report its bogus results as "correct". The Bird reports
a 9:1 SWR on a matched-line 450 ohm ladder-line. Is the SWR really 9:1?

well DUH! obviously if you want to measure swr on a 450 ohm ladder line you
don't use a 50 ohm bird! anyone using a 50 ohm bird has to expect results
to be referenced to its internal 50 ohm line. i.e. if you actually do
measure no reflected power so you know the load on the bird is 50 ohms, and
if you really are in a 75 ohm environment then you can compute what the swr
is on the 75 ohm line... just don't expect the bird to show it to you
directly.