Preselector Bypass Mixer Bias Adjustment

(E4446A, E4447A, E4448A)

This test is performed only on analyzers with Option 123.

Option 123 consists of a Preselector Bypass path where both the microwave preselector in RHYTHM, and the millimeter preselector in the SBTX are bypassed. This bypass path places the millimeter unpreselected mixer in parallel with the preselected RHYTHM / SBTX mixers. The millimeter unpreselected mixer requires that LO drive levels be adjusted in order to optimize the sensitivity (conversion loss) of the PSA. The LO input for the Option 123 mixer comes from the FELOMA External LO port. This procedure assumes the FELOMA Adjustment has been performed.

In this test the millimeter unpreselected mixer bias is optimized for the lowest conversion loss. A signal is displayed on the analyzer and the mixer bias DAC is adjusted for peak signal amplitude. The mixer has 7 bands and requires adjustment  and DAC value storage in each band. Once the peak amplitude is found in each band, the peak amplitude DAC value for each band is stored in EEPROM.

This adjustment should be performed after replacing the A21 FELOMA, the A38 Option Driver Assembly, the A34 Unpreselected Mixer, or the A35 Mixer Bias board.

This adjustment saves an output file which lists the corrections that were stored in the instrument. The output file is saved at this location:

<drive>:\Program Files (x86)\Agilent TME\PSA\Output\<Model_Serial#>

Required Test Equipment

Test Equipment

Model Number

Synthesized Sweeper

PSG Models
(see equipment list)

BNC Cable

8120-2582

2.4 mm Cable

8120-6164

2.4 mm (f) to 2.4 mm (f) adapter

1250-1743

Connection Setup