DRAKE SPR-4 Spezifikationen PDF herunterladen (Seite 30)

6.3.4

CIRCUIT DESCRIPTION

The

BF0

is shifted in frequency for RTTY reception by shunting a capacitor

across

T17 with an electronic switch .

Transistor Q2 electronically

switches C2

across

T17, and Q3 switches C3. Switch S14R

connects

the

collector

of Q1 to the base of Q3 in CW and to the base of Q2 in LSB .

(RTTY

jack)

shorted,

Q1 conducts and turns on either Q2 in LSB

or Q3 in CW, allowing reception of RTTY signals .

6.3.5

SERVICE DATA

A voltage chart ,schematic and a circuit board layout , Figure 14 are

provided for servicing the RY-4.

6.3.6

ALIGNMENT

Place the mode switch in t he USB position and the RF gain control fully

clockwise . The position of the crystal selector, range switch and pre

s elector is unimportant.

Connect a clip lead with a

series

blocking

capacitor of 1000 pf between the terminal on

T15

and the

10 K resistor of

the SCC-4 crystal calibrator. See Figure 8 and Figure

Adjust

the slug in T- 17 for

zero

beat .

Remove the clip lead and replace the

cabinet.

If an SCC-4 is not available, follow the

BF0

alignment in

“5.3.1” and make certain the RTTY

jack

on the rear of the SPR-4

not

connected

to ground

6.4

6.4.1

MODEL TA-4 TRANSCEIVE ADAPTOR

GENERAL DESCRIPTION

The TA-4

Transceive

Adaptor allows the SPR-4 to

transceive

with the T-4A

T-4B/T-4X/T-4XB Drake Transmitters .

6.4.2

INSTALLATION

This modification should be made by a competent technician . If you need

help or want the TA-4 to be installed by one of

our

factory authorized

service centers or by the factory service

technicians,

please

call

write

our Customer Service Department.

Disconnect the speaker

table

and the line

cord

and remove the SPR-4

cabinet. Mount the TA-4 circuit board with two number 4 sheet metal

screws and two lockwashers (with the lockwashers between the

screw-

heads and the mounting

feet)

in the

chassis

holes

shown

in Figure 16

Connect the five

color

coded TA-4 circuit board wires by pushing the

connectors

at the end of

each

wire

onto

the appropriate mating pins in the

SPR-4 until they are fully seated.

See Figure 17 for the location of the

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