User's Manual

5-46
5.18 XMT CRYSTAL OSCILLATOR FREQUENCY CORRECTION
PURPOSE
See Figure 5 - 19 and follow the procedure to correct the transmit frequency of the crystal
oscillator on the UD-35() Transmitter module.
Allow a 1-hour warm-up period for radio and test equipment before starting applicable
tests or improper frequency adjustment can result. If waiting for initial alignment is
impractical, it may be performed after a warm-up period of 5 minutes minimum; however,
crystal frequency should be rechecked after full warmup.
Figure 5 - 19 XMT Crystal Oscillator Frequency Check
PWR MON
XMT PWR
ALM
ON LINE
I CARR NULL
XMT LVL
ADJ
FREQ CONT
Q CARR NULL
TRANSMITTER
RF
OUT
XTAL
MON
RF
MON
FREQ
COUNTER
Connect Frequency Counter to XTAL MON connector.
a
Verify XMT LO frequency indicated on Frequency Counter
is crystal reference frequency ± 3 parts per million. If not,
adjust Freq Cont.
b
Check/adjust Carrier Null using Spectrum Analyzer
(Paragraph 5-22 or 5-23) or DVM (Paragraph 5-24).
c
MDR-1053
02/09/07