HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual 4-1
4 Technical description
This section of the manual contains a technical description of the 9323, 9360,
9390 or 9780 transceiver and 9330, 9366, 9391 or 9782 control head. It should be
read together with the drawings in chapter 9, Drawings.
Control and supply voltages
All switching, except power On, is controlled either directly or indirectly by the
microprocessor IC101 (located on the Microprocessor and Audio PCB) in
conjunction with the microprocessor IC2 in the control head.
Power on
1 04-02974
When the On/Off button on the control panel is pressed, the PWR ON line (P4
pin 3) is pulled low via the series circuit consisting of diode D1 on the On/Off
button and D3.
The cathode of D3 is at 0 V prior to switch on, permitting the PWR ON line to
momentarily be held low by discharged capacitors on the 5 V rail.
1 04-02976 Sheet 2
The PWR ON line on the front panel is connected via a short cable to P201 pin 3
located on the Microprocessor and Audio PCB. From there it is fed via R222 to
the base of transistor V203.
1 04-02976 Sheet 2
The PWR ON line from the extended control head is connected by a control cable
to the transceiver rear panel connector P204 pin 4, then via a ribbon cable to the
Microprocessor and Audio PCB (P203 pin 7). From there it is fed through an RF
suppression network (L205 and C236) then connected in parallel to the front
PWR ON line, then via R222 to the base of V203.
With the PWR ON line low, V203 conducts and energises the ON coil of latching
relay K201 resulting in contacts K201 closing and applying a ground to the TCVR
ON line.
The TCVR ON line is connected from the Microprocessor and Audio PCB via
P101 pin 3 (see Sheet 1) to P1 pin 3 on the PA assembly [1 04-02973 and
04-03096] and finally to the negative side of relay K8.
If the polarity of the DC supply is correct and below 16 V, V4 will conduct and
relay K8 will energise, closing contacts K8-1 and connecting the DC supply to the
transceiver. The PWR ON line is disabled on start up when D3 on the control head
is reverse biased by the 5 V supply.
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