RT CARD CALIBRATION-CONT.

T.O. 31W2-2GSC24-2

TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3010

3. Determine if the frequency measured in

NOTE

step 2 is within plus or minus one part in 107 of the

oscillator's specified output frequency. If the measured

To ensure proper calibration, allow the

frequency is within this tolerance, proceed to step 5. If

frequency counter to warm up for

the measured frequency exceeds this tolerance, proceed

approximately 15 minutes before making

to step 4.

frequency measurements.

NOTE

1. Loosen and remove printed circuit access

cover (figure 6-2) located at front of chassis.

When the nominal specified frequency of

the installed oscillator is 9.8304 MHz, the

NOTE

acceptable tolerance is

+9.8304 x 10 or approximately Hz.

Steps 2 through 4 are applicable only

when the multiplexer is operating from an

internally generated reference timing signal

4. Using a standard screwdriver,

remove

(paragraph 3-74).

If the multiplexer is

protective cover from RT card reference timing oscillator

operating from a station clock or other

adjustment control (figure 6-8). Using an electronic

external reference timing signal, proceed to

tuning tool, slowly rotate oscillator adjustment control

step 5.

until frequency measured at TP-10 of RT card is within

the tolerance established in step 3. Replace protective

Connect frequency counter to test point TP-

cover.

10 of RT card (figure 6-8) and measure output frequency

of reference timing oscillator Y1.

5. Connect frequency counter to TP15 of RT

card (figure 6-8) and measure frequency of transition

NOTE

encoding signal.

The multiplexer set is initially delivered with a

Determine that the frequency measured in

reference timing oscillator whose nominal output

step 5 is 4800 +0.24 Hz.

frequency is 9.8304 MHz. For certain applications,

oscillators of different frequencies may be installed.

.If the measured frequency is within

If the frequency measured at TP-10 is not

tolerance, proceed to step 8. If the measured frequency

approximately 9.8304 MHz, determine the specified

is not within tolerance, set POWER CONTROL switch to

nominal frequency of the installed oscillator before

OFF and replace RT card as prescribed in paragraph 6-

proceeding.

22. Set POWER CONTROL switch to ON and repeat

steps 5 through 7.

8. Install and tighten printed circuit card

access cover.

6-34