DRAKE L7 Operator'S Manual Download | Manualshive

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Summary of Contents for L7

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Page 3: ...OPERATOR S MANUAL LINEAR AMPLIFIER ...

Page 4: ...0 R L DRAKE COMPANY 1979 PRINTED IN U S A ...

Page 5: ... 2 2 2 11 TRANSMITTING AGC 2 2 2 12 VOX RELAY 2 3 r 4PTER 3 OPERATION 3 1 3 1 GENERAL 3 1 3 2 TUNING PROCEDURE 3 1 3 3 CW AND RTTY TUNING 3 1 3 4 SSB AND AM TUNING 3 1 3 5 OPERATION 3 3 3 6 CW AND RTTY OPERATION 3 3 3 7 SSB OPERATION 3 3 3 8 AM OPERATION 3 3 3 9 SWR CALCULATION 3 3 3 10 OPERATION ON ACCESSORY FREQUENCIES 3 4 CHAPTER 4 THEORY OF OPERATION 4 1 4 1 INPUT 4 1 4 2 TRANSMITTING AGC 4 1 ...

Page 6: ... 2 INPUT COIL ADJUSTME 5 3 METER ADJUSTMENT 5 3 WATTMETER CALIBRATION 5 3 NULL ADJUSTMENT 5 3 300 WATTS REFLECTED 5 3 300 WATTS FORWARD 5 3 3000 WATTS FORWARD 5 4 KNOB POINTER ALIGNMENT 5 4 POWER SUPPLY CIRCUIT BREAKER RESET 5 4 REMOVING THE BOTTOM COVER 5 4 REMOVING TOP COVER 5 4 POWER SUPPLY TROUBLESHOOTING 5 4 ...

Page 7: ...S 7 POWER SUPPLY AND THE R L DRAKE LINE OF COMPATIBLE EXCITERS 2 6 VIEWING ANGLE OPTIONS 2 7 FRONT PANEL CONTROLS L 3 2 PLATE VOLTAGE AND PLATE CURRENT VS 1 000 WATTS DC INPUT POWER 3 5 SWR NOMOGRAPH 3 5 COMPONENT LOCATIONS TOP VIEW 5 5 COMPONENT LOCATIONS BOTTOM VIEW 5 6 CONNECTIONS FOR GRID CURRENT METER r CALIBRATION 5 7 MODEL L7 POWER SUPPLY SCHEMATIC DIAGRAM 5 7 MODEL L7 LINEAR AMPLIFIER SCHE...

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Page 9: ... Aninternal changeoverrelay feeds CHAPTER 1 INTRODUCTION the antenna through when theL 7isturned off A pair of relay contacts bias the outputtubes to cut off eliminating unwanted heat and diode noise whenreceiving Twometers indicateplatecurrent grid current plate voltage RF output power and RFreflectedpower TheseparatesolidstatePower Supply requires no warm up period and provides excellent dynamic...

Page 10: ...twork matches 50 ohm line with SWR not to exceed 25 Intermodulation Distortion Products In excess of 33dB Wattmeter Accuracy 300 Watts forward and r e flected 5 of reading 3 Watts 3000Wattsforward 5 of reading 30Watts Power Requirements 240 Volts 50 60 Hertz 15 Amperes or 120Volts50 60 Hertz 30 Amveres Tube Complement Two of 3 5062 or 8802 3 5 0 0 2 or 8163or 3 4002 Dimensions Amplifier 1 11 6 in ...

Page 11: ...aps g 2 Cables 1 Vox Relay 1Transmit AGC h 1Plug Pin Vox Relay i 2 Resistors 0 82 Ohm 2 Watts placement spares for Power Supply R12 j 2 Rubber Feet ForViewingOptionB k 2 studs to attach rubber feet CHAPTER 2 INSTALLATION 1 1Instruction Manna1 READZ F m 1Warranty F g i r a t i o n Card N r n EFll out the enclosed Warranty Regidrdon card and returnittothe r y h n e d i a t e l y to insue tion and va...

Page 12: ...ecauseof thepossibilitythat you maybe qsing a multiband antenna orhave afeed linethat is resonant at a harmonic frequency it is highly recommended that a suitablelow pass filter such as theR L Drake Model TV 3300 be used with the L 7 2 8 MATCHING NETWORK Most practical antennas exhibit an SWR range over a complete amateur band that exceeds 2 l For this reason we recommend using an antenna matching...

Page 13: ...ne end of the cable in place of thephmo when used with thesemodels For TR7 s and similarexcbs ir i s w observe the correct polar when t e a l h e VOX RELAY circuit If aphonoconneebrisaed this is automaticall3 a m m p l d u d If a tropin connector is used the wrred polarityi sobginsd with the folloaiingp d m Placerbe in STANDBY and set the Li MODE s w i t c h to C X the ON OFF switch to Oh and theS...

Page 14: ...TYPE ACCEPTANCE LABEL HIGH VOLTAGE CONNECTOR J5 i I J6 I CONNECTOR I I L e n J4 Fig 2 1 Rear Chassis Connectors ...

Page 15: ...120 VOLT OPERATION Amplifier Power Supply Figure 2 2 Jumper Connectionsfor 720 Volt Operation 240 VOLT OPERATION Amplifier Power Supply Figure 2 3 Jumper Connections for 240 Volt Operation I _ ...

Page 16: ...Fig 2 4 Connecting the PS 7 Power Supply and the R L Drake Line of Compatible Exciters ...

Page 17: ...OPTION A i OPTION B I N V E R T E D FRONT FEET miSUPPLIED WITH UNIT SUPPLIED WITH UNIT Fig 2 5 Viewing Angle Options ...

Page 18: ... NOTES ...

Page 19: ... 2NT which has no transmitting AGC switch off AGC in TUNE CW and AM modes It is not necessary to defeat AGC exter nally on DrakeTransmitters other thantheTR 7 3 3 CW AND RTTY TUNING Preset the front panel controls on the L 7 as follows a Mode switch to CW b Band switch to desired band c Meter switch to 3000 W A m FWD d STBY switch to operate out e LOAD fully counterclockwise to zero f PLATE wntrol...

Page 20: ... exciter connected straight through to the antenna 5 AGC Control Adjusts the transmitting AGC threshold 6 ON OFF Switch Turns the main power on and off 7 MODE Switch Selects highplate voltagefor SSBoperation orlowplate voltagefor CWoperation oi for tuning 8 Meter Switches Select indication for Multimeter 1 9 PLATE Control Resonates the plate tank circuit 10 BAND Switch Selects input andplate tank ...

Page 21: ...xciter either by an oscil lator or by whistling a single tone into the micro phone with theexciteradjusted formaximum out put With this single tone applied turn the AGC control clockwise until the plate current is 0 580 Amperes If you desiretorun lessthan 2kilowatts PEP turn the AGC control clockwise until the single tone plate current decreases to the power level you desire Return the Mode switch...

Page 22: ...the load can be determined by subtracting the reflected power from the forward power J y 3 10 OPERATION ON ACCESSORYkyS 2 i z FREQUENCIES 4 Bandswitch Position Freauencs in MHz 3 7 The input coils may be retuned for frequencies 7 r moderately removed from the amateur bands For frequencies far removed it may be necessary to change the values of the capacitors in the input T i circuit A ...

Page 23: ...ate Amperes 1900 1800 PLATE VOLTAGE PIATEAMPERES Figure 3 2 Plate Voltageand Plate Current VS 7 OYIO Wans DC Input Power mawup OmC Imo 7Q YO so a 100 70 P 30 V S W I m r ntn u 1 SW R CALCULATOR R I DRAKECO MIAMISBURG OHl0 Figure 3 3 SWR Nomograph ...

Page 24: ...NOTES ...

Page 25: ...e voltage proportional to the RF signal applied to the input appears atthe transmitting AGC output connector THEORY OF OPERATION 4 3 STANDBY CUTOFF BIAS A positive voltage f r o m the resistor divider R9 R10 and R11in the PowerSupplyis appliedtothe cathode during standby which cuts off the plate current 4 4 OUTPUT The plate circuit is matched to the 50 ohm output by the adjustable pi networkconsis...

Page 26: ...NOTES ...

Page 27: ...teps in sequence 1 Disconnect the Power Supply from the power source 2 Disconnect the AC Power connector from the amplifier 3 Disconnect the High Voltage connector from the amplifier 4 Reverse the above order to reassemble the Amplifier 5 3 AMPLIFIER DISASSEMBLY The cabinet is secured by 6screws 3on each side of the unit Remove the screws and lift off the cabinet There are three easily removable p...

Page 28: ...the WARNING in paragraph 5 2 and remove the tubes b Attach an ohmmeterbetween the grid and fila ment of the tube to be tested Goodtubes willindi cate infinite resistance Bad tubes will indicate a short circuit Intermittent tubes will indicate a momentary short when tapped lightly 5 9 ALIGNMENT PROCEDURES Referto figures5 1and 5 2asrequiredtolocatethe components requiring adjustment 5 10 INPUT COIL...

Page 29: ...e Meter to their original locations g The high voltage adjustmentpotentiometerRl7 is not user adjustable If this needs readjust ment return the L 7 to the factory for service See paragraph 5 1 5 12 WATTMETER CALIBRATION The wattmeter in the L 7 was designed to keep maintenance to a minimum The wattmeter is a passive device and it should provide years of service and maintain its calibration If cali...

Page 30: ...wer the bottom cover of the Power Supply can be removed by taking out all of the screwsaround the bottom of the chassis 5 20 REMOVING TOP COVER WARNING BE SURE that the L 7 Power Supply is un plugged from its power source The top cover cannot be removed until thebottom cover has been removed After the bottom has been removed removethe line cord wires from the barrier strip and ground The top can t...

Page 31: ...PARASITIC CHOKES RF PLATE CHCUE PC 1 PC 2 RFC 4 GRID RENT C42 CAL POT R 19 Fig 5 1 Component Locations Top View ...

Page 32: ...I 120 22 1V mMINAL STRIP SEE FIG 2 3 FILERS LOW P A S FILTER Fig 5 2 Component Locations Bottom View ...

Page 33: ...L 7 CHASSIS PUSH BUTTON BOARD Fig 5 3 Connections for Grid Current Meter Calibration RtJ TNmUllf 6 IRE ISOX HY I20 V 7w QR 24OV ISA POWER Ra POWER LINE GND POWER CONNECTOR SHOWN FROM SOLDER CONNECTION END Fig 5 4 Model L 7 Power Supply Schematic Diagram ...

Page 34: ...NOTES ...

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Page 37: ... Dwg D4788 Fig 5 5 Model L 7 Linear Amplifier Schematic Diagram nr R i 1 2 3 28 6 8 7 30 8 11 9 10 2o 12 13 1 4 15 17 27 4 22 2 5 2 1 24 28 3 5 8 11 12 16 28 22 30 2 1 68 24 z7 SO 27 32 80 34 36 39 4145 7 8 13 1 4 9 47 81 48 42 43 2 4 17 I8 25 28 35 38 37 58 40 44 61 48 52 48 50 63 5654 6268 6367 A2 4 8 8 5 7 10 15 9 11 ...

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