SEA 222 Operator's Manual page 62

7.1.6
+13.6 VOLTS Tx BUSS
The transmitter predriver circuitry and the bias systems for the
transmitter driver are supplied with a -relatively high' current +13.6
Volt buss through PNP switch, Q2. This transistor is l·ocated on the
PA/Filter board and is connected as an inverted switch. Base drive is
supplied from the relay control driver, Ul. The same driver port which
is used to prove base drive to Q2 is also used to switch the antenna
circuit T/R relay, Kl. Oiode steering through CR4 and CRll prevents
interaction between the relay and transistor circuits.
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