SGC Smartuner SG-211, Operating Manual

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SG-211 User’s Manual
© 2004 SGC Inc. Page 37
The output of the L network can be left floating to drive
balanced antennas or one side can be grounded for
unbalanced antennas. Providing the balun on the input
side of the network means that it is normally operated
with a matched load. Locating the balun on the output
side as in some other tuners, means that the balun sees
much more stress with a mismatched load.
4.3 The Sensor
Transformers T2 and T3 form a directional coupler. D1,
D2 and associated circuitry detect forward and reverse
power that is fed to the microprocessor A/D inputs. The
microprocessor wakes up when the forward power
exceeds the minimum threshold. If significant reflected
power is detected, the matching sequence is initiated.