Transformer, Power, Isolation and Step-Down TF-248/G

p r e s s e d a n d t h e contacts of S901

P901 is a two-prong male plug that

a r e s e t t o their closed-circuit

m a t e s a two-socket female recep-

p o s i t i o n . To a s s u r e that the main

tacle on' the right wall of the main

unit power supply operates into its

unit tuning unit compartment (fig.

n o r m a l load, however, the ac in-

4 6 ) . Withdrawal of a tuning unit

p u t powerline is still incomplete

f r o m the tuning unit compartment

u n t i l the action described in (3)

o p e n - c i r c u i t s microswitch S711;

b e l o w is accomplished.

this action disables operating

(3) Male m U l t i p i n connector P903.

p o w e r from the main unit power

Connector P903 consists of 18

transformer T702 (fig. 6). The con-

s t r a i g h t single-conductor pins and

d u c t o r s connected to plug P901

2 coaxial-conductor plugs. When

serve as a jumper to restore oper-

P903 is mated with receptacle

ating power to the main unit trans-

J 7 0 1 , mounted on the inside rear

former T702. However, the jumper

w a l l of the tuning unit compart-

circuit is completed only when

ment, the 18 single-conductor pins

m i c r o s w i t c h e s S901 and S902 are

d e p r e s s e d to their closed-circuit

provide a path of continuity for the

a c and dc potentials developed in

p o s i t i o n , as described in (2) and

(3) below.

the main unit for tuning unit oper-

(2) Female multipin connector P902.

a t i o n . Coaxial conductor pin Al

s e r v e s as the termination for the

Connector P902 consists of 18

s t r a i g h t single-conductor sockets

s h i e l d e d wire that provides a dc

a n d 2 coaxial conductor sockets.

p a t h for the audio output signal

When P902 is mated with the recep-

from the tuning unit to audio ampli-

tacle at the rear of the tuning unit

fier V701 in the main unit. Coaxial

under measurement, the 18 single-

c o n d u c t o r pin A2 provides a path

c o n d u c t o r sockets provide a path

for the rf or calibrating signal from

of continuity for the ac and dc po-

the main unit to the rf tuner section

of the tuning unit. Connector P903

tentials developed in the main unit

f o r tuning unit operation. Coaxial

s e r v e s o n e additional function,

conductor socket A1 serves as the

similar to that of P902 ((2) above).

t e r m i n a t i o n for the shielded wire

This function is the closing of the

contacts of microswitch S902,

that provides a dc path for the audio

which is physically located on the

signal developed in the tuning unit

to audio detector V701 in the main

h o u s i n g for connector P903. As

P903 mates with main unit recep-

unit. Coaxial socket A2 provides a

t a c l e J701, the protruding plunger

path for the rf signal (which enters

o f the microswitch is depressed

the test set through the main unit)

and the contacts of S902 are set to

or for the calibrating signal (devel-

t h e i r closed-circuit position. With

oped by impulse generator G701 in

S901 on connector P902 closed ((2)

the main unit) to the rf tuner section

a b o v e ) , this action completes the

within the tuning unit. In addition

to providing dc paths of continuity,

j u m p e r circuit across tuning unit

compartment m i c r o s w i t c h S 7 1 1

connector P902 serves another

function. T h i s f u n c t i o n i s t h e

(fig. 6), and the ac input power to

c l o s i n g of the contacts of micro-

t h e main unit transformer is re-

s w i t c h S901, which is physically

s t o r e d . The power supply works

l o c a t e d on the housing for con-

into its rated load, which consists

n e c t o r P902. The plunger of the

of an operating tuning unit.

microswitch e x t e n d s approx-

62. Transformer, Power, Isolation and

i m a t e l y one-half inch beyond the

Step-Down TF-248/G

connector housing. As P902 mates

(fig. 40)

w i t h its receptacle on the rear of

the tuning unit, the plunger is de-

a. 120V Position of S802. This external