CHAPTER 5. Q-MULTIPLIER/NOTCH FILTER

TM 11-5820-554-12

CHAPTER 5

Q-MULTIPLIER/NOTCH FILTER

Section I. INTRODUCTION

NOTE

The Waters Q-Multiplier/notch filter was originally purchased and installed in

the RT718/FRC-93 transceivers for use in Europe. This item is no longer in the

supply system for replacement; however, the information in this chapter is

retained to provide maintenance information for those which are still in use.

Multiplier/notch filter is greatest in the rejection of

5-1. Description

heterodynes, it is also useful in rejecting all types of

a. The Q-multiplier/notch filter (Waters 340-A),

interfering signals such as continuous wave (cw),

hereafter referred to as the Multiplier/notch filter, is

amplitude modulation (am.), and single sideband

designed to increase the operating capacities of

signals (ssb) that are close to the desired signal.

Receiver-Transmitter RT-718/FRC-93 by providing the

c. The mechanical design of the Multiplier/notch

ability to tune out interfering signals. It provides

filter when installed in the Collins KWM-2/2A will not

facility for simultaneous fixed-station use of the

detract from the equipment's original appearance or

external permanently tuned oscillator (pto) (Collins

electrical performance.

It may be installed in

312B-5) together with the Multiplier.

approximately 1 hour.

b. The Multiplier/notch filter operates at 455 kHz

2.6 Hz. Its tunable notch depth is 40 db at any point in

the entire IF passband. While the usefulness of the

5-2. Items Comprising an Operable Q-Multiplier/Notch Filter

NSN

Item

Qty

5915-00-911-2333

Filter, band suppression kit w/attached coaxial cable 94603; Q-multiplier/notch filter (Waters 340-A) ...................... 1

Capacitor assembly group; MSA-B-340-26 (including MSA-B340 1 and MSA-B340 41); 94603 ............................ 1

Filter assembly MSA-B34-10; 94603 ............................................................................................................................ 1

Installation kit group: type 340-A; 94603 ..................................................................................................................... 1

5960-00-166 7664

Electron tube 12AX7, 81349 ........................................................................................................................................... 1

Section II. OPERATION

c. Set the REJECTION TUNING knob (outer

5-3. Adjusting Q-Multiplier/Notch Filter

knob) at 12 o'clock. The capacitor plates will be at half

a. Turn the new inner knob to ON. Allow the

mesh.

transceiver to warm up for 10 minutes.

d. Tune the vfo dial to 1.1. kHz lower frequency

b. Turn the inner knob to CAL, the EMISSION

than zero beat. The tone in the speaker will be 1.1 kHz.

switch (on Collins KWM-2/2A) to USB, and tune the

e. Two null positions may be found when adjusting

vfo dial to a crystal calibrator frequency; for example,

the tuning screw in L1. Use that position found when

4.000 MHz. Set the AF GAIN control to maximum,

the screw is turned ccw and is farthest out. Rotate the

and the RF GAIN control between 3 and 5 o'clock.

tuning screw slowly for a null at 1.1 kHz. tone.

Change 5

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