DRAKE R-4C Especificaciones descargar pdf (Pagina 21)

b.

C.

d

e.

f.

g-

h.

green. Connect a 10,000 Ohm resistor from the

more easily accessible of the two rotor contacts

on Sl D to ground. From the corresponding rotor

contact of Sl E, connect a 10,000 Ohm resistor

to B+. The easiest point to make this connection

is the red and white striped wire on the terminal

strip near S 1 E.

Disconnect the antenna from the

R-4C,

and

connect a 47 Ohm resistor from the center of

the antenna jack to ground.

Plug the 12.6 MHz crystal into one of the acces-

sory crystal sockets.

Set the receiver right side up on the bench and

turn the PRESELECTOR knob as far clockwise

as possible. Carefully measure the distance from

the top of the slug of Tl to the top of the white

liner projecting through the hole in the top of

Tl

. The distance was set at the factory to exactly

9/l

6 inch. Check the measurement carefully be-

fore altering the position of the slug. The dis-

tance that the slug projects must be exactly

9/l

6

inch. Check the setting of the slugs in T2, T3,

and T4. All must have the same

9/l

6 inch pro-

jection.

Turn the receiver on, set the BAND switch to

28.5, the FUNCTION switch to CAL, and tune

in the calibrator signal at (28.7 MHz. Allow the

receiver to warm up for a few minutes.

Adjust the PRESELECTOR knob so the slugs in

Tl

through T4 project exactly 15/32 inch above

the white liners.

Refer to figure 5-1. Adjust the four trimmers

marked 28.7 for maximum S Meter reading. If

the calibrator signal is insufficient to produce an

adequate S Meter indication, remove the 47 Ohm

resistor from the antenna input, and connect the

signal generator to the antenna input. Set the

R-4C FUNCTION switch to EXT. MUTE, ad-

just the signal generator to 28.7 MHz, and set

the generator output level to cause an S Meter

indication of approximately S-7. Adjust the four

trimmers marked 28.7 for maximum

S

Meter

indication.

Repeat steps f and g for each band, using the

settings given below:

BAND

SLUG HEIGHT

FREQUENCY

21.0

7/l

6 inch

21.3 MHz

14.0

1

l/32

inch

14.3 Mhz

7.0

3/l

6 inch

7.3 MHz

3.5

Flush with White sleeve

3.8 MHz

1.5

Flush with White sleeve

1.9 MHz

NOTE: For the 1.5 band, the XTALS switch must

be set to the position corresponding to the number

of the socket into which the 12.6 MHz crystal was

inserted .

i. Turn off the

R-4C,

and remove the alignment

resistors.

5-13. S METER ADJUSTMENT.

a. Tune in a 1 microvolt signal from the signal gen-

erator on the 40 meter band. Peak PRESELEC-

TOR and PASSBAND for maximum strength.

b. Set S METER ZERO control on rear panel to

mid-range.

Adjust R33 for S-3 reading.

Remove signal and adjust the bias potentiometer

R5

5 for S-l reading.

Apply a 30,000

micro

signal and adjust the S

METER sensitivity adjustment R36 for 60

dB

over S-9.

Repeat steps a.through e. several times if

necessary.

5-14. CRYSTAL CALIBRATOR ADJUSTMENT.

a.

b.

C.

d.

e.

Connect the antenna to the

R-4C,

and set the

receiver controls for AM reception of WWV.

Tune in WWV.

Refer to figure 5-l and determine the location

of c174.

Insert a shorted plug in the MUTE jack, and set

the FUNCTION switch to CAL.

Adjust the audio gain until you can hear the beat

note between WWV and the calibration signal.

Adjust Cl74 for zero beat with the WWV signal.

5-3

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