Alc - Kenwood TS-890S In-Depth Manual

TRANSMISSION CIRCUIT 03
Fig. 18 Tx Delay OFF Selected (Left) and 35 ms Selected (Right)

ALC

For use with a linear amplifier or transverter, it is possible to connect an external device to the ALC terminal (pin 6) to
enable proper transmit power control.
The ALC signal is a signal output from an external device that shifts the voltage to the negative side (for KENWOOD
transceivers) when the transmit power reaches the range to be restricted from the external device standpoint. External
devices generally have voltage adjustment VRs (variable resistors). On the TS-890S, applying a negative voltage to the
ALC terminal reduces the internal gain. The operating point is described later.
As described above, the conventional method of control is by inputting ALC signals from the linear amplifier. However,
this method is no longer recommended on recent transceivers. This is because excessive power is applied to the linear
amplifier before ALC voltage is input from the it, and this may cause damage to the linear amplifier. Also, the protection
circuit inside the linear amplifier may be activated. To prevent such excessive input, adjust the transmit power to a proper
level in advance.
● Recommended Operation
On the TS-890S, configure the maximum transmit power that can be input to the linear amplifier in advance. The ALC
control in the transceiver activates at high-speed, thus it can limit the output power without receiving an ALC signal from
the linear amplifier. The transmit power limiter described later is useful for this.
After the abovementioned setting is complete, apply the ALC signal of the linear amplifier to the ALC terminal of this
unit. Doing so protects the linear amplifier when it has to limit the transmit power, or in cases such as when the transmit
power of the TS-890S is increased by mistake.
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