HP TM 11-6625-2779-14&P Manuel d'utilisateur télécharger pdf (Page 36)

Section V Model 3555B

Figure 5-1. Balanced BNC to 310 Plug

function, remove or clip the shorting bar

from across A1 R17 (see Figure 7-2).

b. Remove the 150 BAL decal from the small

envelope supplied with the set and stick it

over the existing 135 BAL decal.

c. Adjust the 150 function as described in

Paragraph 5-20 in this manual.

5-7. PERFORMANCE CHECKS.

5-8. The performance checks presented in this

section are in-cabinet checks designed to compare the

Model 3555B with its published specifications. These

checks can be used for incoming inspection, periodic

maintenance checks and to verify performance after

adjustment or repair. A performance check test card

appears at the end of this section which can be used to

record the specification performance of your set.

5-9. LEVEL ACCURACY CHECKS.

a. Connect only the 654A and 3555B as

shown in Figure 5-2 and set the 3555B

controls as follows:

FUNCTION........... CARRIER, 75 UNBAL

INPUT .................................TMS, TERM

RANGE......................................+10dBm

b. Set the 654A frequency to 20kHz,

IMPEDANCE to 75 UNBAL and adjust the

output level for +10dBm. If the calibration

of the 654A is questionable, first connect

the output of the 654A through a 75 ohm

termination, directly to the input of the

3440A/3445A (3555B not connected) and

measure the voltage. This level should be

866mV rms. If it is not, adjust the 654A

amplitude control until it is and note the

654A meter indication for future reference.

Now that the 654A calibration has been

verified, disconnect

Figure 5-2. Level Accuracy Check

5-2

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HP TM 11-6625-2779-14&P Manuel d'utilisateur Page 36