SBE SB2-LA - Page 8

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unless

both

switches

are

to

the

right.

With

either

switch

left,

operation

of

the

transceiver

will

be

"straight

through'’*

when

the

microphone

button

is

pressed.

CAUTION:

POWER

PLUG

POLARITY

CAN

AFFECT

OPERATION

OF

SBZ-

IN

CASE

OF

ERRATIC

METER

ACTION

OR

"LOUD

HUM

IN

mene

CEIVER

SPEAKER,

REVERSE

115V

AC

POWER

PLUG

ON

SB2-LA.

Prior

to

actual

tune-up

of

the

amplifier,

the

transceiver

(or

exciter)

should

be

loaded

to

the

desired

band

into

the

antenna

to

be

used.

This

may

be

done

by

temporarily

turning

the

power

toggle

switch

to

LO

position

and

tuning

the

transceiver

in

the

normal

manner.

Then

turn

the

TUNE-OPERATE

switch

to

OPERATE

position

and

the

power

switch

to

HI.

With

the

transceiver

micro-

phone

button

pressed

but

not

delivering

output

(microphone

gain

control

to

zero)

see

that

the

PLATE

AMPERES

meter

on

the

amplifier

reads

.3.

If

not,

ad-

just

the

bias

control

on

the

rear

panel

as

required.

Be

sure

transceiver

or

exciter

carrier

has

been

nulled

before

checking

idling

current.

Set

the

BAND

switch

to

the

desired

band

and

the

LOAD

control

fully

counter-

clockwise.

With

the

power

switch

on

HI,

tune-operate

switch

on

TUNE,

band-~-

switch

on

desired

band,

and

load

control

fully

counter-clockwise,

put

trans-

ceiver

in

TUNE

position.

Then

adjust

the

tune

control

for

a

sharp

dip

in

the

plate

amperes

meter

and

a

rise

in

the

OUTPUT

meter.

Check

transceiver

output

for

maximum

drive

into

linear

amplifier.

Place

amplifier

tune-oper-

ate

switch

in

OPERATE

position

and

adjust

amplifier

controls

for

plate

amperes

meter

reading

of

1.2

(.95

on

15

meters).

CAUTION:

DO

NOT

OPERATE

THE

AMPLIFIER

IN

'"'TUNE"

POSITION

FOR

MORE

THAN

30

SECONDS

CONTINU-

OUSLY:

This

completes

the

tune-up

procedure

for

single-sideband

operation.

Turn

the

transceiver

mode

selector

to

USB

or

LSB

position

and

set

the

microphone

gain

control

for

an

amplifier

plate

amperes

reading

of

about

.5

while

speak-

ing

a

steady

''AHHH"!

into

the

microphone.

This

setting

may

be

rnade

more

accurately

if

output

from

the

amplifier

is

monitored

by

an

oscilloscope.

The

setting

should

be

increased

to

just

below

the

point

where

peak

clipping

(flat-

topping)

occurs.

On-the-air

checks

should

be

taken

with

caution;

they

are

sub-

ject

to

error

and

may

be

quite

misleading.

;

The

SB2-LA

linear

amplifier

is

designed

to

operate

with

any

mode

of

emission

normally

employed

on

the

high-frequency

amateur

bands.

For

amplitude

modu-

lated

(AM)

service,

the

above

tune-up

procedure

is

followed

except

that

the

final

drive

adjustment

is

made

for

a

plate

amperes

reading

of

not

more

than

.38.

Similarly,

for

FM

or

FSK

operation,

the

final

drive

adjustment

is

made

*«

Transceiver

output

directly

connected

to

antenna

through

SB2-LA.