MODEL 8559A

ADJUSTMENTS

ADJUSTMENTS

5-25. FIRST CONVERTER ADJUSTMENTS(Cont'd)

Adjust front-panel TUNING FINE control to place a comb tooth on the first vertical graticule line of the CRT display.

Adjust A7R92 FM to place a comb tooth on the ninth vertical graticule line of the CRT display.

Switch to 10 kHz RES BW and adjust A7R83 DC for even spacing of the comb teeth on the first two graticule lines.

Readjust TUNING FINE control to place a comb tooth on the first vertical graticule line. Adjust A7R92 FM to place a comb tooth on each of the graticule lines while keeping the first comb tooth aligned using the TUNING FINE control.

Repeat steps 25 and 26 to achieve the best span linearity.

NOTE

Trim potentiometer A7R83(DC) controls the amount of delay compensation; A7R96* controls the time constant of the compensation. If the adjustment of A7R83 does not result in even comb tooth spacing, R96* will have to be re-selected for even spacing.

Switch to 30 kHz RES BW. The comb tooth spacing should not change. If there is a shift of the comb teeth, repeat steps 22 through 27 for best compromise in span linearity.

Tune to approximately 100 MHz and verify that a comb tooth placed on the first vertical graticule line, using the TUNING FINE control, will align the ninth comb tooth with the ninth vertical graticule line +1 minor division.

Select the 10 kHz RES BW and verify that a comb tooth on the first vertical graticule line will align the ninth comb tooth with the ninth graticule line +1 minor division.

Select the 30 kHz RES BW and repeat step 29 for a frequency of approximately 2.5 GHz.

Repeat step 30 for a frequency of approximately 2.5 GHz.

If necessary, A7R83 (DC) and A7R92 (FM) may be compromise adjusted for best span linearity at the three frequenciesindicated.

Set comb generator for 100-MHz comb teeth.Adjust front-panel TUNING control for 0.10 GHz indication on FREQUENCY display.Set FREQ SPAWDIV to 2 MHz.Adjust TUNING to place 100-MHz comb tooth on center graticule line.