Transmit Power Limiter; Alc Operation When An External Device Is Connected - Kenwood TS-990S In-Depth Manual

04 TRANSMISSION
● Recommended Operation
Set the maximum transmit power, that can be entered to the linear amplifier, to the TS‑990S 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.
As configured as described above, apply the ALC signal of the linear amplifier to the ALC terminal of the TS‑990S. If
the linear amplifier has to limit the transmit power, for example, in the case where the transmit power of the TS‑990S is
increased by a false operation, this protects the linear amplifier.

Transmit Power Limiter

The transmit power limiter prevents the transmit power from exceeding the pre‑configured transmit power level. Pressing
the [MAX‑Po] (F) key opens the TX Power Limit screen. The screen allows the configuration of the transmit power
by band. Continuously rotating the [PWR] knob clockwise increases the transmit power to the configured maximum.
Consequently, transmit power limit for use in DATA mode and transmit power with TX tuning can also be configured.
An external device such as a linear amplifier may have different gains or withstanding input powers by band, thus the
required transmit power varies in most cases. The TX Power Limit screen allows the configurations for the transmit
power by band. If the maximum transmit power has been configured on the screen, this eliminates troublesome transmit
power adjustment with the [PWR] knob each time the band is changed.
Selecting "ANT1" for the antenna connector when an external antenna tuner is connected limits the maximum transmit
power to 100 W. Even if the transmit power limiter is set to 100 W or higher, "00 W" appears on the lower line of the
[MAX‑Po] (F) key and the transmit power on the main screen (top center).
Note:
◆ Transmit power cannot be configured individually for each antenna connector (ANT1 to ANT4).

ALC Operation when an External Device is Connected

"Connection Block to an External Device for ALC Signal Input" shows the block diagram of a signal circuit to enter the
TS‑990S ALC signal from an external device and control the TS‑990S internal ALC amplifier.
It employs a method to control the TS‑990S gain by using an ALC voltage entered from an external device; however,
it consequently serves to control the TS‑990S transmit power. This operation is common for both linear amplifiers and
transverters. A change in the DRV output level by the ALC voltage represents a change of the output level of the ALC
voltage entered from the external device. The gain decrease will be noticeable in the TS‑990S IF circuit upon a drop in
voltage to below ‑7 V. The gain decrease also leads to reduction of the transmit power (ANT output and DRV output); this
serves for output control.
22
Fig. 34 Setting Screen for the Max Power Limiter Function