Attenuator

TB 11-6625-2747-50

Figure 2. Rear interior view.

b. Adjustments.

tune output frequency and matching network (B14) for

maximum deflection on receiver (A7) NULL meter.

(1) Remove TI from case.

(5) Phase lock and level signal source and fine

(2) Adjust R85 (fig. 2) for a pulse width less

tune for an oscilloscope display of 30 mHz ±25 kHz

than 0.5 microseconds wide as indicated on the

(difference of local and reference oscillator frequencies).

oscilloscope.(R)

(6) Adjust RF power output of signal source

(3) Adjust PULSE WIDTH control of TI for a 10

utilizing level set attenuator (B2) number 2 for 0.9 ma as

microsecond wide pulse as indicated on the

indicated on CRYSTAL CURRENT meter of receiver.

oscilloscope.

(7) Adjust REFERENCE ATTENUATOR control

(4) Loosen knob setscrews and slip PULSE

of receiver for 0 db as indicated by ATTENUATION-DB

WIDTH control so that 10 is located under panel index

digital readout of receiver.

marker.

Tighten setscrews.

(R) Repeat the

(8) Turn TI MOD SELECTOR switch to OFF.

performance check.

14. Attenuator. a. Performance Check.

(9) Turn POWER LEVEL-OSC. OFF control of

receiver counterclockwise to OSC. OFF.

(1) Connect equipment as shown in figure 3.

CAUTION

(10) Adjust NOISE BALANCE control of receiver

Since

ferrous

materials

may

for zero as indicated on NULL meter.

NOTE

permanently damage magnetic fields

Do not readjust NOISE BALANCE

of the BWO tubes used in the RF

control for the remainder of this

head

assembly,

keep

ferrous

procedure.

materials away from BWO tubes and

use only nonferrous tools when

(11) Turn TI MOD SELECTOR to CW and

working near BWO tubes.

stabilize at frequency and power output as in (2) and (3)

above.

(2) Adjust TI controls for a CW output frequency

(12) Turn POWER LEVEL-OSC OFF control of

of 12.75 kmc.

receiver to POWER LEVEL.

(3) Adjust TI OUTPUT ATTEN DBM control to 0

(13) Adjust level set attenuator number 1 for null

db.

(zero reference) as indicated on NULL meter of receiver.

(4) Adjust controls of signal source (A) for a CW

output frequency of approximately 12.75 kmc. Coarse