Mathew,
A 1.5 dB insertion loss will result is an output that is 0.708 of the
input. For 150 watts input, this would result in about 106 watts
output. A lot of assumptions are made in arriving at this ballpark
figure! First of all, your PA output into a 50 ohm resistive load is
not going to be the same when it is feeding a highly-reactive load such
as a duplexer cavity. The presence of a ferrite isolator will affect
your readings. The interconnecting cables, connectors, and (gasp!)
adapters will add additional attenuation.
One of the recurring topics on this list is the perceived or actual
mismatch between the transmitter PA output impedance and the duplexer's
input impedance. This "dead horse" is forever going to rise from the
ashes and create dissension and discord among the ranks, so we can't
ignore it. Suffice it to say that such a mismatch may be greatly
reduced by a careful selection of the interconnecting cable length,
which creates a sort of impedance transformer. You may also use an
integral impedance matcher, sometimes called a "Z-matcher," to introduce
a compensating impedance and achieve an optimum power transfer.
Whichever method you choose, it's worth exploring.
73, Eric Lemmon WB6FLY
w9mwq wrote:
> I am curious with a set of TX-RX duplexers at 1.5 insertion loss,
> input power of 150 watts, what would be the power output? Need to
> know, as I don't think they are tuned correctly, or something might
> be wrong here.
>
> Mathew
>
>
> Yahoo! Groups Links
>
>
>
>
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