R.L.DRAKE R-4A Instruction Manual
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R.L.DRAKE R-4A Instruction Manual

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Summary of Contents for R.L.DRAKE R-4A

  • Page 2: Table Of Contents

    TABLE OF CONTENTS General Specifications I General Description II Installation Instructions Unpacking Location C. Power Requirements D. Antenna Requirements Speaker Requirements F . Anti-VOX G . M u t i n g III Control Functions Front Rear Jacks Side Controls & Jacks IV Operation Preliminary Control Settings Single Sideband or Double Sideband Suppressed...
  • Page 3 Notch Filter Alignment Passband Tuner Alignment Bias and S-meter adjustment CHARTS AND ILLUSTRATIONS Connecting R-4A to TR-4 Transceiver Fig. # F i g . # 2 Viewing Angle Option Fig. # 3 Rear View Fig. # 4 Crystal Freg. Chart Fig.

  • Page 4: General Specifications

    30 M with the exception of 5.0-6.0 M SELECTIVITY: Drake tunable passband filter provides: .4 KC at 6 DB down and 2.6 KC at 60 DB down 1.2 KC at 6 DB down and 4.8 KC at 60 DB down 2.4 KC at 6 DB down and 8.2 KC at 60 DB down...
  • Page 5 TUBES AND SEMICONDUCTORS: TUBE FUNCTION 12BZ6 R.F. amp. 12BA6 100 KC calibrator 6HS6 1st mixer 6HS6 Premixer 12BE6 2nd mixer and xtal oscillator 12BA6 50 KC I.F. 12BA6 50 KC I.F. 2N3394 AVC amp./AVC det. 2 - 2N3394 Audio amp. 6EH5 Audio output 12BA6...

  • Page 6: I General Description

    I GENERAL DESCRIPTION The DRAKE R-4A is an extremely versatile communication receiver de- signed to bring you every feature desirable for the ultimate in the reception of all modes of amateur communications. It provides a linear permeability-tuned solid state VFO with 1 KC readability, and premixed injection with crystal controlled high frequency A 100 KC crystal calibrator is built-in.

  • Page 7: Installation Instructions

    Inspect the packing material closely before putting it away to be sure that you have not overlooked any accessory hardware. LOCATION In general the location of the R-4A is not critical. However, care should be taken to insure that space is allowed around the unit for adequate air circulation.

  • Page 8: Speaker Requirements

    Antenna connection to the R-4A is provided at the jack on the rear of the chassis marked ANT. It is recommended that when the R-4A is used with a transmitter, the trans- mitting antenna be used; change-over being accomplished by an antenna relay.

  • Page 9: Connecting R-4A To Tr-4 Transceiver

    R - 4 A AC-4/MS-4 o r R V - 4 T R - 4 y--- -- - ---I This switch must b e in the TCVR position f o r t r a n s c e i v i n g a n d in t h e R C V R p o s i t i o n f o r s e p a r a t e...

  • Page 10: Control Functions

    160 through 10 meter amateur bands. FUNCTION - The FUNCTION switch is a six position switch used to select the method of operating the R-4A. When in the OFF position the power transformer primary is opened, When in the STBY position, the power thus turning the unit off.
  • Page 11 by the transmitter. When in the N. B. position the noise blanker is energized, and when in the CAL position, the noise blanker is switched off and the calibrator is switched on. In these last two positions the muting function is the same as if the switch were in the EXT-MUTE position, so if external muting is not used, a shorted plug must be inserted in the Mute jack to obtain these functions.

  • Page 12: Rear Jacks

    PASSBAND tuning knob setting. The audio frequency at maximum signal strength will be correct. PHONE JACK - A PHONE JACK is provided on the front of the R-4A for private listening when desired. The jack automatically mutes the speaker output when headphones are plugged in.

  • Page 13: Side Controls & Jacks

    SIDE CONTROLS & JACKS S-METER ZERO - This control is the front-most adjustment on the right side of the R-4A chassis and is for the purpose of setting the S-meter needle to S-l under no signal conditions. NOTCH ADJ. - The NOTCH ADJ. control located on the right side of the chassis is a balancing device whichdetermines the amount of attenuation obtained with the T-notch filter.

  • Page 14: Operation

    IV OPERATION A. Preliminary Control Settinqs For all modes of operation set these controls as follows: FUNCTION BAND Set to desired amateur band (see “accessory frequency coverage” for information concerning coverage of other frequencies) XTALS NORM PRESELECTOR Peaked for maximum S meter reading on operating frequency NOTCH R.F.

  • Page 15: Am Reception

    Under crowded band conditions it will be advantageous to use the 4 KC selectivity position and reposition the Passband knob for maximum S-Meter reading on a signal tuned in to the desired pitch. After the Passband control is adjusted thus, simply tune in a C W signal for maximum S-Meter reading and it will automatically be the correct pitch.

  • Page 16: Adjusting Dial Calibration

    “0” mark coincides with the indicator line. Noise Blanker Operation The noise blanker in the R-4A is an I. F. device which turns off the receiver during a noise pulse. It is equally effective on all modes of operation and greatly attenuates most impulse noise.

  • Page 17: Operation Of Notch Control

    Operation of NOTCH control The notch control on the R-4A consists of a permeability-tuned T-notch This filter is capable of producing a deep notch filter in the 50 KC I. F. which can be tuned across the receiver’s I. F. for the elimination of interfering carriers in all modes of operation.

  • Page 18: Accessory Frequency Coverage

    In addition to reception on 80, 40, 20, 15, and the 28.5 - 29.0 portion of 10 meters, the R-4A can be programed to receive any ten 500 KC-wide ranges between 1.5 and 30.0 mc (excluding 5.0 to 6 .O mc) by inserting the appropriate crystal in one of the ten accessory crystal sockets.
  • Page 19 1 . 5 a n d 3 0 m c ( e x c l u d i n g 5 .0 - 6.0 mc) NOTE that if you intend to transceive with the R-4A, the crystal chart in the T4/T4X b o o k s h o u l d b e f o l l o w e d i n s t e a d .

  • Page 21: Fixed Frequency Operation

    “Accessory Frequency Coverage” for the desired frequency. If a T4X is being used, placing the T4X TRANSCEIVE switch on SEP.CONT. will result in the T4X being VFO controlled while the R-4A is xtal locked. Placing this switch in the RCVR position will lock the T4X on the R-4A lock frequency.

  • Page 22: Theory Of Operation

    V THEORY OF OPERATION A. R.F. Amplifier A signal entering the antenna is applied to the grid of the low noise 12BZ6 R. F. amplifier tube (Vl) through the tuned circuit formed by the coil Tl and capacitors C21 through C31. Here it is amplified and the output is tuned by the circuit formed by coil T2 and capacitors Cl through C11.

  • Page 23: Second Converter

    Second Converter The 5645 KC output of V2 is applied to the grid of the 12BE6 second This gives excellent cross mod- converter (V3) through a crystal filter. ulation and overload characteristics by providing selectivity before the gain producing stages. cathode, control grid and screen grid are connected in a Pierce oscillator configuration controlled by a 5595 KC crystal.

  • Page 24: F I G . # 6 Selectivity C Urve S

    FREQUENCY KILOCYCLES NOTE‘ PASSBANDS A R E CONTINUOUSLY MOVABLE ABOVE AND BELOW EIFO, FREQUENCY. FIGURE X 6 - SELECTIVITY CURVES K I L O C Y C L E S (6 FO) FIGURE # 7-EFFECT OF NOTCH ON 2.4 KC SELECTIVITY CURVE -23-...

  • Page 25: Audio Output

    Audio Output Audio signal from the AF GAIN potentiometer is applied to the grid of the 6EH5 audio output tube V-7 through two stages of AF amplifiers consisting of Q7 and Q8 and associated circuits. The audio output from this tube is then applied to the speaker or phones through audio output transformer T16.

  • Page 26: Noise Blanker

    I. Noise Blanker The noise blanker in the R-4A attenuates a received noise pulse by shunting to ground the output of V-4 during the time interval of the pulse.
  • Page 27 The negative bias supply uses a IN3194 diode to provide -60 volts to the AVC system for minimum bias, muting, and control of RF Gain. An OB2 voltage regulator VII is incorporated to provide 108 volts regulated for operation of the xtal calibrator. A IN714 zener diode, in conjunction with V11 provides 10 volts regulated for the VFO and H .F.

  • Page 28: Service Data

    SERVICE DATA We will check and factory align your R-4A for a nominal fee of $10 .OO plus transportation charges if the set has not been tampered with. If repairs are necessary, an additional charge will be made. Units that have been tampered with or misaligned, will be repaired on a time and material basis only.

  • Page 29: F I G . # 9 Voltage Chart

    Figure #9 VOLTAGE CHART Number Type 12.6* 12BZ6 - 1 . 1 1.66 6HS6 6.3* 12.6* 2 . 8 12BE6 - 1 1 . 5 2 . 7 12.6* 12.6* 12BA6 - 1 . 1 12BA6 - 1 . 2 12.6* 6EH5 2 .
  • Page 30 Figure #l0 RESISTANCE CHART Number Type 12BZ6 4.4M 6.5K 6HS6 2.2M 6.5K 228K 2.2K 12BE6 6.5K 6.5K 12BA6 4.2M 6.5K 12BA6 3.7M 6EH5 500K 500K 16.1K 7.2K 6HS6 350K 4.7K 12BA6 2.6M 6.5K 8.3K 12AX7. 158K 4.5K 3.2M 20K* 700K 700K 12BA6 390K...

  • Page 33: Alignment Instructions

    ALIGNMENT INSTRUCTIONS Alignment of the R-4A will require the following equipment. A reasonably stable signal generator having a frequency range from 1.5 to 30.0 mc and variable output level. An 11 megohm vacuum tube volt meter (VTVM) A 12.6 mc series resonant crystal.

  • Page 34: Crystal Filter And Filter Match Transformer Alignment

    C. Crystal Filter and Filter Match Transformer Aliqnment Attach signal generator to pin #l of V2 and set generator frequency to 5645 KC. Set level so that an S-Meter reading of approximately S-9 is obtained. Set Passband selector switch to 2.4 KC and set Passband knob until it points horizontally to the left.

  • Page 35: Antenna Rf, And Injection Circuit Alignment

    Antenna, RF, and Injection Circuit Aliqnment Turn off receiver and temporarily connect a 10K resistor from the side rotor contact of S 5 C to ground, and from the corresponding contact of S5D to the nearby terminal strip terminal to which the red and white striped B+ wire is attached.

  • Page 36: 100 Kc Calibrator Alignment

    100 KC Calibrator Alignment Attach the antenna to the R-4A and tune in WWV at the frequency For crystal selection see the chart most reliable in your area. on page 18. Set the Function switch to CAL. (A shorted plug must be inserted in the Mute jack).

  • Page 37: Bias And S-Meter Adjustment

    band tuning knob should be pointing horizontally to the left as viewed from the front. If it is not, loosen the knob set screw and reposition the knob. Tune in a crystal calibrator signal at 3.8 mc for zero beat. Set the Passband selector lever to and set the Passband tuning knob to the center of the shortest line.

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