DACS Accuracy CheckPositive Supply

Adjustment

20.50 MHz Voltage-Tuned Oscillator Adjustments

3.Connect DVM to A22TP9 and ground lead to A22TP12.

4.Key in [SHIFT) [CF STEP SIZE] J 0 Hz. If using an HP3456A DVM, pressISTORE_)aZ, way, a, (STORE)@JY, then

@El 0 (X-Z)/Y.If not using an HP 3456A DVM, note voltage indication for reference later.

5.Key in [m] [CF STEP SIZE) J 1023 kHz.

6.If using an HP 3456A DVM, voltage indication should typically be be + 10.230 fO.O1O V de. If not using an HP 3456A DVM, voltage indication should be + 10.230 fO.O1O V de plus the indication noted in step 4. If voltage is within tolerance, proceed to next step. If voltage indication is incorrect, go to Adjustments 18, Frequency Control Adjustments, and perform YTO and VT0 DAC adjustments.

7.On the HP 3456A, press MATH off.

8.Key in &ENTER FREQUENCY) 1 MHz, [FREQUENCY SPAN) 1 MHz.

Connect DVM to AllTP5 and ground lead to Al 1 cover.

9.Key in ISHIFT) ~CF STEP SIZE) J 12 kHz. (CRT annotation should indicate DACS 12.)

10.Key in (SHIFT) (MKRW1 N. (CRT annotation should indicate VT0 frequency of approximately 28.75 MHz. This corresponds to a VT0 frequency of 57.5 MHz, since the counter indication is divided by two.)

11.Adjust All OFFSET AllRlO and/or All GAIN AllR9 for VT0 frequency of 28.750 MHz f0.005 MHz as indicated by CRT annotation. See Figure 3-79 for location of adjustment.

A l 1

50MHr VOLT! 1GE-TI J N E D O S C I L L A T O R

J

u

 

 

A l 1

 

 

 

 

Figure 3-79. Location of 50 MHz VT0 Adjustments

12.Note DVM indication for reference later.

13.Connect DVM to AllTPl (located on All cover).

Adjustments 3-131