"Cecil Moore" wrote in message
news
Dave wrote:

"Cecil Moore" wrote:
Yes, that's exactly what I said in the other posting. But some
people seem to believe that inserting a Bird into a transmission
line with a Z0 other than 50 ohms magically changes it to a 50
ohm environment. The 40mm of transmission line inside the Bird
is supposed to accomplish that miracle.

yep, that is true, and that is what the experiment shows. the 50 ohm
load, even though it is caused by a 75 ohm line, is far enough away from
the sensor that it sees it as 50 ohms. so the 'miracle' length is
obviously less than 40mm.

So a one inch piece of 50 ohm coax forces the ratio of net voltage
to net current to be 50 ohms? Of course it does. You had me going
there for awhile. I didn't realize until now that you were pulling
my leg all the while.
--

yep, sounds good to me. now, someone please put a bird meter on a tdr and
see what the characteristic impedance of it is internally. then put it on a
network analyzer and see if it does indeed transform the 'environment' from
75 to 50 ohms in its 40mm length. oh and while you are at it calculate the
s factors for all the transitions, those will come up in the discussion here
shortly.