Technical description
4-38 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
PA Exciter Interface
108-05226 and 04-03092
The 9323, 9360, 9390 or 9780 series transceivers may be fitted with a PA Exciter
Interface assembly replacing the 100/125 W PA assembly.
Transceivers fitted with the PA/Exciter Interface assembly are identified by a
letter H suffixed to their type number, which is located on the rear of the panel.
This assembly is designed for use with Codan Power Amplifier type 4404.
The microprocessor detects when the PA/Exciter Interface assembly is fitted and
provides the necessary control commands to operate the PA/Exciter Interface
PCB.
Filter and PTT control
[1 04-03092]
The band filters, PTT and high/medium/low power on the Power Amplifier type
4404 are selected by the microprocessor in the transceiver.
Serial data from the microprocessor IC101 [1 04-02976] is applied via the local
I
2
C bus to IC2 (serial data input 8-bit output driver) on the PA/Exciter Interface
PCB (P1/14, 15 and 16). The outputs of IC2 pins 11, 12, and 13 provide the BCD
switching lines to select the filters. Pins 14 and 15 select the high, medium and
low transmit power levels to the Power Amplifier type 4404.
When PTT is selected, the microprocessor IC101 [1 04-02976] sends serial data
to IC2, which latches pin 16 to ground. This grounds the PTT line to the 4404 and
at the same time forward biases V1, providing the DC supply to the transmit
amplifier V3, V4 and V5.
Power On/Off
In the power off state, contacts K1/C and D are in the open position. The 24 V DC
supply connected to the Power Amplifier type 4404 is fed via the two series
connected power relays K8 and 9, and D10 on the Filter PCB [1 04-01817 (HF
4000 series)], through the connecting cable to P2/6 on the PA/Exciter Interface
PCB [1 04-03092] . From here it passes through RF filter network L5 and C6 to
charge C1 to about 13 V. The remaining volts are dropped across V7 and D6.
At the moment of switch on, the POWER ON line (P1/3) from the transceiver
goes low applying the charged voltage across C1. This energises the ON coil of
the latching relay K1. This results in the contacts of the latching relay K1/C and D
closing and grounding the POWER ON line to the Power Amplifier type 4404.
With this line low, relays K8 and 9 energise, applying 24 V to all circuits in the
Power Amplifier type 4404.
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