Rf Gain Adjustment; Agc Off - Kenwood TS-990S In-Depth Manual

RF Gain Adjustment

KENWOOD HF‑band transceivers are designed with our consistent philosophy to balance the levels, such as the
sensitivity, S meter needle deflection, pre‑amplifier gain, gain correction, and other factors. If the input level from an
antenna is low, (internal) noise may be conspicuous. If noise is conspicuous, reducing the IF gain can lower the noise
level. For that purpose, the [RF] knob is provided. Rotating the [RF] knob counterclockwise reduces the IF gain and
consequently lowers the noise level. Slightly lowering the gain does not change the reception sensitivity. The S meter
shows the gain reduction by the AGC and the [RF] knob, thus the S meter needle deflects by the gain reduction. In the
range the AGC is applicable, the S meter sensitivity does not change.
Placing the [RF] knob to the 3 o`clock position reduces the IF gain by approximately 6 dB from the maximum and
reduces the noise level at no signal by approximately 6 dB. The gain reduction causes the S meter needle to deflect
closer to S3. A 6 dB gain reduction causes the sensitivity to change little, and the reception sound volume does not
change with reception of a usual signal that makes the S meter needle deflect. If the noise level is noticeable, adjust the
RF gain.

AGC Off

The AGC time constants for such as the attack time, release time, and hold time are optimized for a practical radio
waves state. However, for reception of a signal easily buried in noise, turning the AGC off may occasionally increase its
performance. In such a case, the AGC can be disabled with a press of the [AGC OFF] key.
With the AGC inactive, the signal level will not be controlled to be the certain volume level, and the speaker may emit
very loud sounds. This is why a confirmation message appears before the AGC is turned off to prompt attention to loud
sounds.
Before turning the AGC off, you must adjust the RF gain to a signal level that makes the S meter needle deflect. Rotate
the [RF] knob counterclockwise to lower the RF gain, letting the S meter needle deflect slightly wider. This prevents loud
sounds from being emitted while the AGC is inactive.
If a large signal is entered while the AGC is inactive, the S meter needle deflects up to the level specified for the RF gain
and the reception sound volume increases up to a certain level. However, if this level is exceeded, the reception audio
volume reaches its limit and sudden distortion takes place. This is intended to set limits so that the allowable levels are
not exceeded in the D/A converter and through signal processing.
RECEPTION 03
15