Section III. OPERATOR'S MAINTENANCE INSTRUCTIONS

TM 11-5820-554-12

f. Adjust potentiometer R8 for minimum tone.

5-4. Q-Multiplier/-Notch Filter

Alternately, readjust both L1 and R8 for the best null.

Effectiveness

g. Retune the vfo dial and the rejection tuning. The

The Q-Multiplier/notch filter effectiveness can be

tone may be found and pulled.

increased when RF GAIN control R8 is less than

h Replace the antenna connection on the rear of the

maximum. When the Q-multiplier/notch filter is not

chassis.

necessary, it should be tuned out of the passband (dial

NOTE

pointer in the horizontal position). The Q-

The Q-multiplier/notch filter (Waters

multiplier/notch filter does not cause reduction in the

340-A) will operate in the Collins KWM-

receiver sensitivity; therefore, an in and out switch is

2/2A with either the a.c. power supplies

not provided. Variable capacitor C6 in this unit may be

(PP-4151/95 or PP-3990/ FRC-93), the

rotated continuously. There will always be two

mobile direct current (d.c.) supplies (PP-

positions 180 degrees apart at which a signal can be

4765/GRC-159(V) (24 volts)), or the

notched out.

Collins MP-1 (12 volts). The external

5-5. Use of External Vfo

permanently tuned oscillator (pto) C-

When the external vfo is to be used (only with the PP-

7517/FRC-93 may not be used

4151/FRC-93 or PP-3990/FRC-93), remove the

simultaneously unless the a.c. power

shorting plug from the new socket (J17). Insert the vfo

supplies are used because of heater

plug.

voltage distribution.

Section III. OPERATOR'S MAINTENANCE INSTRUCTIONS

Perform weekly as well as before operation PMCS if:

5-6. General

a You are the assigned operator and have not

The instructions contained in paragraphs 3 19 through

operated the item since the last weekly.

3-22, and 3-24 are applicable for the operator's

b. You are operating the item for the first time.

maintenance duties. Paragraph 5-7 contains the

NOTE

operator's daily preventive maintenance checks and

The checks in the interval column are to be

services chart. Cleaning is covered in paragraph 3-24.

performed in the order listed.

5-7. Operator/Crew Preventive

Maintenance Checks and Services

B-Before

W-Weekly

M-Monthly

D-During

A-After

Item

Interval

Equipment is not ready/ available if:

No.

Item to be inspected

Procedures

Notch filter tuning

Check to insure that an

If filter is incapable of reducing interference that causes failure of

interfering signal can be

mission.

notched out. Use external

signal generator to insert

signal at points in full range

of notch filter tuning.

Section IV. Deleted.

Change 6

5-2