[TenTec] 2A GA Omni A, Omni D at w4rrw

[Gary Bold]

Bob,

both my MFJ tee tuners eat watts, because the coil sits too close
to the metal case, which gets warm.  I've replaced the case top with
cardboard, which increases the Q and decreases the losses.

Some years back, I wrote a document describing the theory and
design of tee transmatches, which you can find here.

http://www.phy.auckland.ac.nz/Staff/geb/transm.pdf

For lowest loss, tees should use the largest possible C, as this
decreases the voltage across the coil.  It's possible to estimate the
power loss from the coil Q if you estimate a few other values.  I estimate
that a good tee transmatch will absorb maybe 5 - 15% of the power
applied to it - more for the commercial "miniature, compact" designs.

Gary ZL1AN

At 03:43 PM 6/30/03 -0400, you wrote:
>Well it was the MFJ that seemed to be eatin half my watts.
>The T match (hombrew) worked great. Set C's to low value,
>find resonance with L, peak with C's.
>I suspect the MFJ just loses a lot in the tiny components...
>My traveling 'tuner' is a BCB variable cap, a hand wound coil,
>and some clip leads. Just lay the parts out on the table top, rock,
>or whatever is reasonably flat and non conducting. TX output
>is a pair of 24" clip leads to the matchng network and antenna
>is wire tossed up and out in opposite directions. Simple and works.
>
>-Bob