17. Disconnect the cables connected to IFa in and IFa out of the unit. 18. Adjust the spectrum analyzer so that the compression modulation peak level can be seen clearly on the spectrum analyzer screen. (Use this item as the reference level.) 19. Set the variable resistance attenuator to 0 dB. 20. Adjust control VR1 (RV1) of the RF ASSY so that the bottom level in the compression modulation of the signal comes to the position set in step 7.
21. Repeat the adjustments in section 4.6 and the adjustments in steps 1 to 20 in section 4.8 three times to raise the accuracy. *1 Observe the following values when adjusting the modulation distortion and compression distortion to facilitate the adjustments. � Clear mode: Meter reading � 6/10 dB mode: Noise waveform on oscilloscope
[Adjustment waveform diagram 1] : [Example of Key Modulation Rate (5.5 dB)]
REF 100.9 dBµV 1dB/ VERTICAL 1dB/ ATT 10 dB A_write B_blank
RBW 1 MHz VBW 1 MHz SWP 200 ms CENTER 41.250 MHz
1dB/div VBW:1MHz RBW:1MHz SPAN:1MHz ST:200ms
SPAN 1.000 MHz
Fig. 4-11 Adjustment Waveform Diagram 1
*2 The above shows one example of the adjustment waveform. Be sure to adjust using the attenuator substitution method. Do not perform adjustment on the screen.
4.9 Setting the Switches of the LOGIC Assy
Switch No. S1 S2 S3 S4 S5 ALL OFF ALL OFF 0 NA D
