Procedure for Changing Frequency

TM 11-5895-833-12/NAVELEX 0967-LP-550-1010/TO 31R5-2TSC54-91

s. Repeat the procedures outlined in g and r above for

Should RF LO FAULT INDICATOR lamp go

on at loss of rf oscillator phase lock, when

all remaining down-converters.

t. et test translator POWER ON-OFF circuit breaker

phase lock is reestablished light may flash

for a period not to exceed 180 seconds

to ON. The POWER ON light should illuminate.

before extinguishing.

NOTE

(5) Observe that STATUS meter varies from

The test translator is not used in normal

original setting, the RF LEVEL and RF LO FAULT

operation but provides self-test capabilities

INDICATOR lamps illuminate and the audible alarm

and an auxiliary 5-MHz frequency standard

sounds.

in case of emergency.

(6) Press and hold AUDIBLE ALARM DEFEAT

pushbutton and tune to center scale.

u. Set 70-MHz ON and 5-MHz ON switches to ON

(7) Release

AUDIBLE

ALARM

DEFEAT

(up) position.

pushbutton and note that the audible alarm is silent.

(8) Observe that the RF LEVEL and RF LO FAULT

NOTE

INDICATOR lamps are extinguished.

The LO SEL switch is set to 725 MHz or

200 MHz depending on the frequency of the

NOTES

converters under test.

Set the MODE SELECTOR switch to FM or

DGTL, depending upon the required carrier

CAUTION

operation. Changing MODE SELECTOR

Do not use the 725-MHz local oscillator of

switch setting from FM to DGTL or DGTL to

the test translator to convert input

FM causes RF LO FAULT INDICATOR

frequencies of 7980 MHz and below be-

light to flash for a period not to exceed 180

cause of the possible contamination of the

seconds and then extinguishes. This

loop test by the local oscillator's tenth

indicates noise burst detection is operating

harmonic. The 200-MHz local oscillator is

properly.

used to translate up-converter frequencies

from 7.9 GHz to 7.95 GHz.

(9) Set STATUS SELECTOR switch to each

position in turn and observe the following indications on

3-9. Procedure for Changing Frequency

the STATUS meter:

Under normal operating conditions, all up-converters and

down-converters are pretuned to the desired operating

Portion

Indication

frequency and are set for the required input and output

70 MHz IF

Blue scale

signal levels and modulation modes. Perform the

700 MHz IF

Blue scale

procedures given in a below for changing the frequency

+ 24V

Green scale

of an up-converter, and the procedures in b below for

RF LO TUNE

Red scale

changing the frequency of a down-converter.

STD LVL

Blue scale

a. Up-Converter.

RF LO

Blue scale

(1) Set RF OUTPUT switch to OFF-LINE.

IF LO

Blue scale

(2) Set POWER ON-OFF circuit breaker to ON and

observe that the POWER ON indicator lamp illuminates.

(10) Set RF OUTPUT switch to ON-LINE.

b. Down-Converter.

(3) Place STATUS SELECTOR switch to RF LO.

(4) Set TRANSMIT FREQUENCY SELECTOR

(1) Check to see that proper filter is connected

MHz switch to new operating frequency.

between connector J2 on rf input stripline assembly and

connector J1 on rf conversion stripline assembly. Filter

A7FL1 is required for receive frequencies between 7.25-

NOTE

and 7.55-GHz and filter A7FL2 is required for receive

If frequency change is less than +12 MHz

frequencies between 7.50- and 7.75-GIIz.

from previous frequency, the indicator lamp

may not go on and alarm may not sound.

Perform (6) below to maximize frequency

NOTE

phase lock.

To gain access to the filter assembly,

loosen the captive screws securing the

Change 1 3-20