External Leveling Used With the Optional Step Attenuator

Some external leveling applications require low output power

from the synthesizer. The synthesizer automatically uncouples the attenuator from the ALC system for all external leveling points.

Press ( P O W E R L E V E L ) . Note the display. It shows:

--> ATTEN 0 dB, POWER LEVEL: 0.00 dBm

For example, leveling the output of a 30 dB gain amplifier to a level of -10 dBm requires the output of the synthesizer to be around -40 dBm when leveled. At some frequencies this level is beyond the range of the ALC modulator alone. If so, the LOW UNLVLED warning message is displayed. Inserting 40 dB of attenuation results in an ALC level of 0 dBm, which is well within the range of the ALC. At 20 GHz,30 dB attenuation is a better choice as it results in an ALC level of -10 dBm. This gives a margin for AM or other functions that vary the power level.

For optimum display accuracy and minimum noise, the ALC level should be greater than -10 dBm. This is achieved by using attenuation equal to the tens digit of output power. Example: desired output power = -43 dBm; use:

--> ATTEN: 40 dB , ALC -3 dBm

1.Press POWER (MENU).

2.Select Set Atten @ @ 0).

Hint To obtain flatness corrected power refer to “Optimizing Synthesizer Performance, Creating and Applying the User Flatness Correction Array,” later in this section.

l-26 Getting Started Advanced