ADJUSTMENTS

5-19.LOG AMPLIFIER LOG AND LINEAR ADJUSTMENT (SERIAL PREFIX 22O8A) (Cont'd)

Connect equipment as shown in Figure 5-3. Set signal generator frequency to 321.4 MHz and output level to - 40 dBm. Remove AlOW1from A5J2 2nd CONV OUT. Connect signal generator output through step attenuator and adapters to AlOWl.

Set the TEST-NORM switch A12S1 to the TEST position. T h e signal generator frequency for maximum signal amplitudeon oscilloscope display with step attenuator set at 0 dB.

Set output level of signal generator for a digital voltmeter reading of 700 mV, with step attenuator set at 0 dB and REF LEVEL dBm set to -50.

Set HP 8559A REF LEVEL dBm to - 80 and set step attenuator to 30 dB. Observe digital voltmeter reading.

Adjust A14R3 GAIN LIN for a digital voltmeter reading of 700 mV.Repeat steps 4,5, and 6 until the DVM reading in step 5 is 700 +2 mV.

Set HP 8559A REF LEVEL dBm to -50 and set step attenuator to 0 dB. Change REF LEVEL dBm and step attenuator settings as shown in Table 5-6. If Deviation from Reference is not within the given limits, readjust Al4R3.

TABLE 5-6.LINEAR GAINADJUSTMENTLIMITS

 

 

 

 

 

I

Reference Level

Step Attenuator

Deviation From

h J B 4

Setting (dB)

Reference

 

 

 

 

 

 

 

 

-50

0

Reference(700 mV)

 

 

-60

10

*lo mV

 

 

-70

20

k20mV

 

 

-80

30

k20 mV

d

 

-90

40

k30mV

 

 

 

 

Set HP 8559A REF LEVEL dBm to 0 and disconnect signal generator from step attenuator. Record offset reading (DVM). The offset should be less than +30 mY

OffsetmV

Reconnect signal generator as shown in Figure 5-3. Set Amplitude Scale to 10 dB/DIV and set step attenuator to 40 dB.

Set output level of signal generator for a digital voltmeter reading of 400 mV plus offset recorded in step 9 (algebraic sum). (Example: if offset if -23 mV, set output levelof signal generatorfor a DVM reading of

377my)