Drake R-4C Instruction Manual

CHAPTER I

l-l.
1-2.

TABLE OF CONTENTS

INTRODUCTION

GENERAL DESCRIPTION .....................

MANUAL COVERAGE
SPECIFICATIONS

.......................

.............

.....................

........

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.

Page

l-l
l-l
l-l
l-3

CHAPTER II

2-l.
2-2.
2-3.
2-4.
2-5.
2-6.
2-7.
2-8.
2-9.
2-10.
2-11.
2-12.
2-13.
2-14.
2-15.
2-16.
2-17.
2-18.

INSTALLATION.

UNPACKING
LOCATION

POWER REQUIREMENTS

GROUND...........................

ANTENNA.
MUTE..

ANTI VOX. ..........................

INJECTION ..........................

CARRIER OSCILLATOR.

PTO LAMP. ..........................

SPEAKER...........................

ACCESSORY POWER.......................

ACCESSORY CRYSTAL FILTER INSTALLATION
ACCESSORY CRYSTALS.

NOISE BLANKER ........................

CONNECTION TO T-4XC TRANSMITTER
CONNECTION TO
CONNECTION TO TR-4 OR TR-4C.

.................

..........................

..........................

..........................

.....................

.......

.....................

.....................

.............

.....................

...............

T-4/T-4X/T-4B/T-4XB

TRANSMITTERS.

.................

........

2-l
2-l
2-l

2-l
2-l
2-l
2-2
2-2
2-2
2-2
2-2
2-2
2-2
2-2
2-2
2-3

2-3

2-3
2-3

CHAPTER III

APRIL 1976

3-l.
3-2.
3-3.
3-4.
3-5.

3-6.
3-7.
3-8.
3-9.
3-10.
3-11.
3-12.

OPERATION . . . . . . -. . . . . . . . . . . . . . . . . . .

GENERAL.
FUNCTION
MODE..
MAIN TUNING DIAL
DIAL CALIBRATION
FRONT PANEL CONTROLS

XTALS............................

BAND..
PRESELECTOR
PASSBAND TUNING

GAIN.............................

AGC.............................

NOTCH. ...........................

..........................

..........................

..........................

.......................

.......................

....................

..........................

.........................

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3-l
3-l
3-l
3-l
3-l
3-l
3-3

3-4

3-4
3-4
3-4
3-4
3-5
3-5

TABLE OF CONTENTS (continued)

3-13. S'METER
3-14.
3-15.
3-16.
3

-

17. SSB
3-18.
3-19.
3-20. RTTY
3-21.
3-22.

PHONE-JACK. . . .

S'METER ZERO.

BASIC

CW
AM

NOISE
ADDITIONAL

CONTROL

RECEPTION . .
RECEPTION .

RECEPTION. . . .

RECEPTION

BLANKER . .

TUNING RANGES

SETTINGS

. .

Page

3

5

3 5

.

3 5
3-

5
3 -6
3-6
336
3 -7
3-7
3-7

CHAPTER IV

4-l.
4-2.
4-3.
4-4.
4-5.
4-6.
4-7.
4-8.
4-9.
4-10.
4-11.

THEORY OF OPERATION.

GENERAL
RF AMPLIFIER
PREMIXER
FIRST MIXER
FIRST IF SYSTEM
SECOND IF SYSTEM AND
AGC

CIRCUIT. . . . .

S

METER . . . . . . .

AUDIO
POWER
CRYSTAL

AMPLIFIER . . . .

SUPPLY. . . . .

CALIBRATOR

DETECTORS

. . . . . .

. .

.
.

CHAPTER V MAINTENANCE . . .

5-l. SERVICE DATA.
5-2. MAINTENANCE.
5-3. COVER REMOVAL.
5-4. TEST EQUIPMENT REQUIRED
5-5. TROUBLESHOOTING
5-6. ALIGNMENT INSTRUCTIONS.
5-7.
5-8.
5-9. FILTER MATCH ALIGNMENT.
5-10.
5-11. 5595 OSCILLATOR ADJUSTMENT
5-12. ANTENNA, RF AND INJECTION ALIGNMENT
5-13. S METER ADJUSTMENT.
5-14. CRYSTAL CALIBRATOR ADJUSTMENT

50kHz BFO AND
5645 OSCILLATOR ADJUSTMENT

NOTCH FILTER ADJUSTMENT

IF ALIGNMENT

. . . . . . . .

. . . .

. . . . .

. .

. . . . . . . .

. . .

5-2

5-2

441
441
4-l
4 -1
4-l
4-

1
4-2
4-2
4-2
4-2
4-2
4-2

5-l
5-l
5-1
5-

1
5-l
5-l
5 1
5-2

5-2
5 2
5-2
5 3
5 3

LIST OF ILLUSTRATIONS

Figure

1-1.

2-

1.
2-2.
2-3.
3-1.
3-2.
3-3.
3-4.
4-1.
5-l.
5-2.

5-3.

R-

4C

RECEIVER . . . . . . . . . .

VIEWING ANGLE OPTIONS. . . . . . .

REAR CHASSIS CONTROLS . . . . . . .

CONNECTING THE TR--4C. . . . . . .

FRONT PANEL CONTROLS. . . . . . . .

PRESELECTOR TUNING RANGES . . . . .

AM SELECTIVITY CURVES. . . . . . . .

SSB AND CW SELECTIVITY CURVES . . . .

BLOCK DIAGRAM . . . . . . . . . .

ALIGNMENT
ALIGNMENT LOCATIONS, BOTTOM VIEW . .
ACCESSORY NOISE BLANKER MODEL

SCHEMATIC DIAGRAM . . . . . . . . .

LOCATIONS,TOP VIEW

. . .

4-NB

Page

1 2

2-m

5
2-5
2-3
3-2
3-

7
3 8
339
443
557
5-8

.

5-8
5 --9

. . .

III

CHAPTER I

INTRODUCTION

1.1. GENERAL DESCRIPTION.

The R-4C Receiver is a triple conversion super­heterodyne receiver designed for optimum recep­tion of all types of amateur radio communications.

It provides complete coverage of the 80, 40, 20,
and 15 meter amateur bands and 28.5 to 29.0 MHz
of the 10 meter band with the crystals supplied.
Additional/ coverage of 500 kHz segments between

1.5 and 30 MHz is possible with the addition of
accessory range crystals. Sockets are provided for
up to 15 additional crystals. A highly linear
permeability-tuned solid state VFO and premixed
injection give excellent stability and dial calibration
on all bands. Eight pole crystal filter selectivity
combined with passband tuning and a tunable
notch filter provide superior interference rejection.

Three AGC time constants are selectable from the
front panel and a 25 kHz crystal calibrator provides
convenient markers at 25 kHz intervals throughout

the frequency range of the receiver.

1-2. MANUAL COVERAGE.

This manual is presented in 5 chapters and is ar­ranged for the convenience of the operator and
service technician as follows:

Chapter I
Chapter II

Chapter III

Chapter IV

Chapter V

Introduction (self explanatory).
Installation. Describes the procedures

to be followed prior to operation.

Operation. Illustrates and describes
front panel controls and describes
operation in SSB, CW and AM modes.

Theory of Operation. Describes all
critical circuits and networks.

Maintenance. Provides maintenance
instructions and parts ordering infor­mation.

-

1.1

SPECIFICATIONS

Frequency Coverage

Accessory Coverage:

:

Covers 3.5to 4.0 MHz, 7.0to 7.5

21.5 MHz,and 28.5 to 29.0

MHz.

MHz,14.0to14.5MHz,

21.0to

15 accessory crystal sockets are provided. Coverage of any additional

500 kHz ranges between 1.5 and 30 MHz (except between 5.0 and

6.0 MHz) can be added by installing accessory crystals.

Modes of Operation:

SSB, CW, AM, RTTY.

Sensitivity: SSB Mode: 10 dB signal-plus-noise to noise ratio obtained on 80

10 M amateur bands with less than a 0.25 microvolt signal on the

antenna terminal, on other frequencies less than 0.5 microvolt signal.

Selectivity:

As supplied:
SSB

Mode:2.4kHzat6dB,

AM

Mode:

8.0

kHzat6dB,28

4.2kHz
kHzat

at60dB.

60dB.

With accessory crystal filters:
AM Mode, 2 filters available:

CW

1.5,

6.0 kHz at6

4.0 kHz at6

CW

.5,

CW

1.5 kHz at6
500 Hz at6
250 Hz at6

dB,

10 kHz at 60

dB,

7.5 kHz at 60

.255

Modes, 3 filters available:

dB,

3.0 kHz at 60

dB,

1000 Hz at 60

dB,

600 Hz at 60

dB.

dB.

dB.
dB.

dB.

M-

Stability

:

Calibration:

Spurious Responses:

Image Rejection:

Input Impedance:
Audio Output Impedance:
Audio Output:
AGC:

After warm up, frequency will not drift more than +- 100 Hz, includ-

+-

ing voltage variation of
Better than

+-

1 kHz when calibrated at nearest 100 kHz calibration

10%.

point.
Internal spurious response less than the equivalent of a 1 microvolt

antenna signal on all amateur bands.
(11.29 MHz above desired): Over 70 dB below 23 MHz, 60 dB above

23 MHz.

52 Ohms nominal.

3.2 Ohms to speaker, or headphones, 3000 Ohms anti

VOX.

0.7 Watt at AVC threshold, 2 Watts maximum at less than 5% T.H.D.
Audio Output increases 3 dB maximum for a RF input increase of

100

dB

above AGC threshold. AGC threshold typically 1 microvolt.
Attack time: 1 millisecond
Release times: Slow: 1 second

Medium: 350 mSec
Fast: 50 mSec

Power Consumption:

Size:

Weight:

60 Watts, 120/240 Volts AC,

50/60

Hz.

5.5 inches high, 10.75 inches wide, 12.25 inches deep overall.
17 pounds.

1-3

CHAPTER II

INSTALLATION

2-1. UNPACKING.

Carefully remove the receiver from the shipping
carton and examine it for evidence of damage. If
any damage is discovered, immediately notify the
transportation company that delivered the receiver.

Be sure to keep the shipping carton and packing

material, as the transportation company will want

to examine them if there is a damage claim. Keep­ing the carton and packing is recommended in any
case, as having these available makes packing the
receiver much easier should it ever be necessary to
store it or return it to the factory for service.

Inspect the packing material before putting it away
to be sure you have not overlooked any accessory
hardware. The hardware consists of two studs,

l0-24,5/8

No.
Examine your R-4C to make sure that all tubes
and crystals are properly seated in their sockets.

Fill out the enclosed registration card
and return it to the factory immediately
to insure registration and validation of
the warranty.

2-2. LOCATION.

The location of the R-4C is not critical, as long as
allowance is made for adequate air circulation.
Avoid extremely hot locations. It is recommended
that a minimum clearance of one inch be main­tained at each side of the R-4C. Do not cover the
top with books, paper, or pieces of equipment.

With the studs and rubber feet supplied, it is
sible to position the R-4C for either of two alter­nate viewing angles, as shown in figure
vert the R-4C to either option, the first step is to
remove the bottom cover from the receiver. Re­move the bottom row of three screws on each side
of the receiver, and the cover can be removed.

Remove the rear feet, and snap the small rubber

feet into the holes just outboard from the original

inch long, and two small rubber feet.

NOTE

pos-

2-l.

To

con-

rear feet. For option B, put the bottom cover back
on the receiver. For option C, remove the front
feet from the receiver, invert them, and remount
them on the same screws. Then thread one of the
accessory studs into each of the remounted front
feet. Finally, mount the feet that were removed
from the rear of the receiver on the studs, and put
the bottom cover back onto the receiver.

2-3. POWER REQUIREMENTS.

CAUTION
Operation of this receiver with the wrong
power source may result in serious dam­age.

Refer to figure 2-2. As shipped from the factory
the R-4C is wired for 120 Volt
operation. The receiver may also be operated from
240 V AC by removing the retaining tab and plac­ing the 120/240 Volt slide switch on the rear panel
in the 240 Volt position. Replace the retaining tab
on the opposite mounting screw to prevent the
switch from accidentally being returned to the

120 V position. Operation of the receiver from

240 V with the switch in the 120 V position will
cause serious damage.

2-4. GROUND.

A screw terminal is provided on the rear panel for
connection to the station ground. Also, if used with
the T-4XC transmitter and other accessories, con­nect a ground strap between the ground terminals
of all units.

2-5. ANTENNA.

The jack labeled ANT is the connection point for
the antenna. The nominal impedance of the circuit
is 52 Ohms.

50/60

Hz AC

2-1

2-6. MUTE.

2-11. SPEAKER.

The MUTE jack provides connections for external
standby-receive switching. The external circuit must
isolate the MUTE jack center conductor from
ground for standby, and connect it to the MUTE

jack ground for receive. The R-4C is shipped with

a shorted phono plug in this jack. When used with
a transmitter, remove the shorted plug and connect
the appropriate cable to the transmitter MUTE

jack.

2-7.

ANTI VOX.

High impedance audio is available at the ANTI
VOX jack for use with the anti

VOX circuit of the

transmitter.

INJECTION.

2-8.

The phono jack marked INJ. provides a means of
coupling the premixer system of the R-4C to the
Drake T-4,

T-4B, T-4C,

T-4X, T-4XB or

T-4XC transmitters for transceive operation.

2-9. CARRIER OSCILLATOR.

The jack marked CAR. OSC provides a means of
coupling injection from the T-4XC carrier oscilla­tor to the R-4C receiver. This connection phase­locks the two units to exactly the same frequency
when used in the SSB Transceive mode. No connec-

tion is made to this jack for use with the T-4X or
T-4XB transmitter.

2-10. PTO LAMP.

This jack provides a ground return for the pilot
lamp behind the PTO dial. The R-4C is shipped
with a shorted phono plug in this jack so that the
lamp will light. When the R-4C is used with the
T-4XC transmitter, remove the shorted phono
plug and connect a cable between the PTO lamp

jacks of the two units. The lamp will then light

only when the T-4XC TRANSCEIVE switch is in
the RCVR, SEPARATE, or SPOT positions. In the

XMTR position, the lamp will not light to indicate

that the R-4C PTO is disabled.

The audio output from the receiver is available at
the jack marked SPKR. The output impedance is

3.2 Ohms.

2-12. ACCESSORY POWER.

The accessory power socket, labeled ACCY POWER,

located on the rear of the chassis, provides power

for operating accessories. Maximum load is 6.3
Volts AC at 300 milliamperes and 12 Volts DC at
50 milliamperes. A connection to the antenna is
also available. The socket mates with a Cinch type
5AB2

plug.

2-13. ACCESSORY CRYSTAL FILTER

INSTALLATION.

To install additional crystal filter(s), proceed as
follows: Remove the two screws holding the filter
cover bracket for each position in which a filter is
being installed. The upper position is for the .250
kHz filter, the center position is for the .500 kHz
filter, and the lower position is for the 1.5 kHz
filter. If a filter for the AM mode is being installed,
remove the top cover of the

R-4C,

the mode

switch cover and remove the filter cover bracket

and the 150 Ohm jumper resistor from the AM

filter socket. Very carefully plug each filter straight

into the sockets.

After installing all the filters desired, replace the
cover brackets over each filter and tighten the

mounting screws. Do not attempt to use accessory

filters without installing the brackets as it is very
important to have a solid ground connection be­tween the bottom of the filter and the spring
material.

2-14. ACCESSORY CRYSTALS.

By inserting the appropriate crystals in the acces­sory crystal sockets at the top rear of the chassis, it
is possible to add up to 15 additional tuning ranges

(each 500 kHz wide) to the coverage of the R-4C.
With the exception of the band from 5.0 to 6.0
MHz, these additional ranges may be anywhere be­tween 1.5 and 30 MHz. Only series resonant crystals

2-2

should be used for accessory coverage. Selected
crystals for accessory coverage with the R-4C will
be supplied by the R. L. Drake Company at a nom­inal cost. Contact Customer Service Department at
the address given in paragraph 5-l for price and
delivery information.
crystal frequency for any additional range, see
table 2-l which shows the required crystal frequen­cy and the proper BAND switch setting for the
R-4C for the frequency spectrum from 1.5 to 30
MHz, except for the 5.0 to 6.0 MHz range. How­ever, if you are going to transceive with the Drake
T-4,
the crystal selection table in the transmitter manual

should be followed in selecting accessory crystals.

Remove the screws holding the shield/cover over
the 15 accessory crystal sockets on the rear panel.
Install the desired crystals and replace the cover
and its mounting screws.

2-15. NOISE BLANKER.

To install the optional 4-NB Noise Blanker, re­move the top row of three screws on each side of

the R-4C. Remove the cabinet top. Remove the
jumper plug from the noise blanker socket which is
located toward the rear of the receiver, on top of
the chassis. Retain the jumper plug so that it may
be used if the 4-NB should ever require service.
The 4-NB mounts on the four plastic stand-offs
which are on the metal shields on either side of the
PTO. Align the plastic stand-offs with the four
holes in the 4-NB circuit board with the 4-NB
cable toward the rear of the R-4C. Carefully push
the 4-NB onto the stand-offs until it snaps into
place. Dress the 4-NB cable toward the rear of the
receiver and through the notch in the filter shield
just above the NB socket and under the mode

switch cover. Plug the 4-NB into the NB socket

of the R-4C.

T-4B, T-4C,

To determine the correct

T-4X,

T-4XB,

or

T-4XC,

Turn on the receiver and tune in the crystal cali­brator signal. Detune the PRESELECTOR until
calibrator signal S meter reading is around
Temporarily unplug the 4-NB cable and reinstall
the jumper plug. Compare S meter readings. If the

l/2

gain varies more than
and the jumper plug, adjust R12 (blue potentiom­eter on 4-NB) until S meter readings are equal
when switching between the 4-NB and the jumper
plug. Replace cabinet top.

2-16. CONNECTION TO T-4XC

TRANSMITTER.

For interconnection diagram see the T-4XC in­struction manual.

2-17. CONNECTION TO

T-4XB

Connect as indicated in the transmitter instruction
manual. No connection will be made to the CAR
OSC jack and the shorted phono plug should be
left in the PTO LAMP jack. Follow the instructions
in the transmitter manual for Transceive Alignment
if necessary. When making the adjustment, set the
R-4C PASSBAND TUNING at 12 o’clock and the
MODE Switch to SSB. Other control settings are
the same as stated for the R-4/R-4B. The adjust­ment on the R-4C is C59 located on a PC board on
the top of the R-4C chassis (see figure 5-l). Adjust
this capacitor for zero canary chirps.

2-18. CONNECTION TO TR-4 OR TR-4C.

To use the R-4C as an external receiver with the
TR-4/TR-4C
illustrated in figure 2-3.

TRANSMITTERS.

transceiver, make the connections

S unit between the 4-NB

T-4/T-4X/T-4B/

S5.

2-3