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ALC MULTIMETER CIRCUIT
When you select this function, a portion of the negative ALC voltage developed in the ALC/Power
PCB-610, described earlier, passes through resistors R603 and R312 (LV & Bias PCB-260) to
multiplier meter M-2.
RF I/O SWITCHING PCB AND BIAS RELAY SWITCHING CIRCUITS
All RF T/R relays (RY1 & RY2) and bias relay (K301) are connected in series in the amplifier
keying circuit. The switching voltage is supplied by the +110 VDC 80 milliampere supply located
on the LV & Bias PCB-260. This circuit includes bridge rectifier D302 & filter capacitor C301. The
+160 VDC output is fed to voltage divider resistors R305 & R306 which are surface mounted on
the chassis. +110 VDC keying voltage is dropped across resistor R306 and fed back to R301 and
K301 located on the LV & Bias PCB. 12 volts is dropped across relay K301 and resistor R301.
The rem98 VDC is passed to RY1 and R601 located on the RF I/O Switching PCB-350.
24 volts is dropped across R601 and RY1. 12 VDC is then dropped across RY2 and R603. The
rem62 VDC is dropped across resistor R604. Capacitor C601 and resistors R601 & R602
plus diode D602 form a break make delay circuit for RY1 & RY2. This helps to make the proper
latching and unlatching sequence for relays K301, RY1, and RY2. Transistor Q601 plus
associated components form a electronic switch to key the Amplifier uti15 VDC on transmit
supplied by the transceiver through connector J4. The Amplifier can also be keyed by sinking the
80 milliamperes to ground through connector J3 and the transceiver's keying relay. The
Operate/Standby Switch SW4 located on the front panel must be closed for the keying circuit to
work. Otherwise the amplifier will be bypassed.
TUNED INPUT CIRCUITS
The eight matching circuits contained on the Tuned Input PCB-450 provide a Q of 2. This Q
allows for sufficient bandwidth. The matching network for each band consists of a L-C-L "T"
circuit. Mica trimmer capacitors C705 - C712 provide a means to make adjustments.The
appropriate input circuit is selected by the Tuned Input Band Selector Switch SW3C. SW3C
pr12 VDC to the corresponding relay coil (K701 - K708) which closes the relay contacts.
The RF Input signal supplied by relay RY2 enters the selected matching circuit. It then leaves the
matching circuit and goes to the filament of V1 through coupling capacitors C57 & C58.
