SECTION I DESCRIPTION AND LEADING PARTICULARS

T.O. 12P4-2APX-192

NAVAIR 16-35TS1843-1

TM 11-6625-1646-25

SECTION I

DESCRIPTION AND LEADING PARTICULARS

1-1. GENERAL.

1-2. This technical manual consists of Instructions and

procedures for use by experienced personnel in the

performance of intermediate maintenance and depot overhaul

of Test Set, Transponder Set TS1843A,,APX manufactured by

Stewart-Warner Electronics under contracts F33657-68-C-

1265 and F33657-71-C-0752 (figure 1-1). An illustrated parts

breakdown is also provided in this manual.

1-3. PURPOSE OF EQUIPMENT.

1-4. The TS-1843A is designed to be used with an airborne

SIF IFF transponder system. The Test Set evaluates the

performance characteristics of the transponder system and

provides a go, no-go indication. The Test Set operates in

either of two modes: monitor or test.

1-5. DESCRIPTION OF EQUIPMENT.

1-6. The TS-1843A is comprised of four major assemblies:

mode generator assembly (A2), comparator-decoder assembly

(A4), and power supply and reply evaluator assembly (A3), all

of which plug-in to the main frame assembly (Al). The overall

dimensions of the TS-1843A are approximately 7-55 64 by 3

by 3-3 64 In.; weight is approximately 2 lb. 8 oz. Located on

the ends of the main frame assembly are two R-F connectors,

a power and control connector, and three service adjustments.

The service adjustments are located under an access cover

(figure 1-2). The R-F connectors are utilized to connect the

test set in a direct line between the antenna system and the

Receiver-Transmitter.

The power and control connector

serve as a means of connection from the Transponder Set

Control unit and primary power source to the test set. The test

set is enclosed by four plates which are mounted directly to

Figure 1-2. Test Set Transponder

the main frame assembly. The test set is secured to the

Set TS-1843A, APX (Rear View), Service Adjustments

aircraft by a mount assembly (MT-3513A APX). The mount

assembly measures approximately 7-25 64 by 3-1 4 in. and

f. Reply peak-pulse power

weighs approximately 0.8 oz. The test set Is so designed that

g. Antenna VSWR

by removing and rotating the bottom plate 180 and remounts

h. Reply rate (per cent)

The above characteristics must be within a specified set of

the plate. the test set can be secured to

limits to achieve a go condition. If any one or more of these

the mount assembly in the opposite direction.

characteristics fall to fall within the specified limits, a no-go

condition will result. In the test function a go condition is

1-7. GENERAL PRINCIPLES OF OPERATION.

indicated by an Illuminated indicator lamp located on the

associated Transponder Set Control.

In the monitor

1-8. GO, NO-GO CHECK. The TS-1843A evaluates the

function, a go indication is determined by the indicator lamp

following characteristics of the transponder on a go. no-go

illuminating for a minimum of two seconds and then

basis.

extinguishing. This process will be repeated as long as there

a. Receiver sensitivity

Is a proper input being applied to the test set. A no-go

b. Receiver frequency

condition is indicated by failure of the indicator lamp to

c. Decoding

illuminate.

d. Reply frequency

e. Reply-code bracket-pulse spacing

1-9. IN-FLIGHT FUNCTION. The TS-1843Aprovides the

following dual functions while in flight.

a. Test Function. The test set, when functioning as

an in-flight tester, generates R-F interrogation pulse pairs upon

activation of momentary contact switches

1-1