RECEIVER ALIGNMENT
1
Change the RX test frequency to 33.0 MHz for A-Band radios, 39.0 MHz for
B-Band , 46.0 MHz for C-Band.
•
First Injection
2 No adjustment for first injection is required.
•
Preselector Alignment
3 No adjust ment for the preselector (L201, L202, L203, L204, L205, L206, L207,and
L208 ) is required.
•
Quadrature Detector
4 No adjustment for the quadrature is required.
•
First IF
5
Apply enough modulated ( by 1KHz tone at
±
3KHz (wide) or
±
1.5KHz (narrow)
deviation ) on-channel RF signal to maintain 12 to 15 dB SINAD. Adjust L215,
and L217, L803 and L804 for maximum SINAD, reducing the RF signal generator
output as necessary to stay between 12 and 15 dB SINAD.
NOTE: Do not adjust L801 or L802 unless approp riate test equipment is available
for performing the “Noise Blanker Tuning’’ steps below. Normally, these coils are
tuned for optimum sensitivity as are L803 and L804, then are retuned slightly for
optimum noise blanker effectiveness. If the required test equipment is not avai-
lable, skip steps 6 through 14. If coils L801 or L802 were replaced, they may be
tuned for best sensitivity after adjustment of L215, L217, L803 and L804. Noise
blanker performance specifications, however, may not be met.
•
Noise Blanker Tuning
This procedures requires the additional test equipment shown in Table 2-2.
6 Adjust the pulse generator to obtain a 10 nsec wide pulse, as shown in Figure 2-2.
Set the pulse period controls to obtain 200 u secbetween pulses(the pulse period
is easier to observe on an oscilloscope if the pulse width is temporarily increased
by about 10 times.)
