On Wed, 08 Mar 2006 06:48:29 -0500, Ken C
wrote:

If I put a T-connector on my feedline and a 50 ohm dummy load on each
leg, does the transmitter see 50 ohms, or 25 ohms?

Not necessarily either.

The T connects the branches in parallel, so if you have a 50+j0 load
and any length of 50 ohm coax connected to each of two branches, the
impedance at the T is 25 ohms. If you connect to T to something else
(eg a transmitter) with 50 ohm coax, the SWR on that section will
result in impedance transformation that depends on the coax (vf),
frequency, and length. For example, if you had 3m of RG58C/U at 7MHz,
the impedance looking into the cable would be 36+j24.

You can solve the transmission line transformation with the calculator
at http://www.vk1od.net/tl/tllce.php .

If one leg is not being used, what should be put there (if anything)
for the transmitter to see 50 ohms if the impedance of the other leg
is 50 ohms?

You know the answer to that now, the branches of the T are in
parallel, leave one branch open circuit.

Owen
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