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MODEL

8559A

ADJUSTMENTS

17. POWER SUPPLY CHECKS AND ADJUSTMENTS (Cont'd)

NOTE

The two following voltage adjustments,

10V

and VO (Varactor Offset),

must be performed while the spectrum analyzer is still cold (during first five

minutes after turn

on). If the instrument has been operating longer than five

minutes, turn off the display mainframe, remove A8 and A9 assemblies, and

let them cool on bench for 15 minutes. Replace the two assemblies and

proceed with adjustment of

A9R2 and A8R62 during the first five minutes

after turn

on.

Connect digital voltmeter to

10V test point A9TP7 and adjust

10V potentiometer A9R2 for

voltme

ter indication of

10.000

0.100 Vdc.

Connect digital voltmeter to VO test point A8TP2. Set spectrum analyzer SWEEP TIME/DIV control to

10 ms and SWEEP TRIGGER control to SINGLE. Turn ALT

and SIG IDENT on (pushbuttons

depressed).

Voltage at A8TP2 will alternate between two values each time a sweep is triggered. Trigger sweep a few

times until voltmeter indicates least negative VO voltage. Adjust VO potentiometer

A8R62 for a voltmeter

indication of

2.00

0.10 Vdc.

HP 8559A User Manual

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