THE R-390 COOKBOOK BY A. CARMODY, w2LE/AAR2Q,R
Contents
1. CARMODY AAR2QR W2LE MODULE REV REF PAGE S REMARKS IF SUB CHASSIS 199 120 129 NOTE In the next step you will disconnect two 2 BNC connectors It is important to identify the cables and connectors I use colored marking pens Other methods such as tages tape are OK just as long as you know where the cables Mark or somehow identify the BNC chassis connectors and the cables attached to them 5 Disconnect the cables from the BNC chassis connectors 6 Locate the GREEN phillips head screws on top of the IF SUB CHASSIS and loosen them completely 7 Grasp the IF SUB CHASSIS and carefully remove it from the chassis Try not to disturb the position of the protruding shafts 8 Locate the ballast tube 3TF7 and remove it from it s socket 9 Place the IF SUB CHASSIS on a bench with the bottom of the tube sockets facing you 10 Prepare two 2 lengths of hook up wire Each wire cut to one 1 inch 11 Strip inch of insulation from each end of each wire 12 Locate the ballast tube socket XRT 512 13 Solder one of the jumper wires from Pin 2 to Pin 4 on socket XRT 512 Be careful not to disturb existing wiring 14 Solder the remaining jumper wire from Pin 7 to Pin 5 on socket XRT 512 15 Install either a 12BY7 or 12BH7 vacuum tube and tube shield in socket XRT 512 THIS COMPLETES MODIFICATION OF THE IF SUB CHASSIS UNITED STATES ARMY MARS MILITARY AFFILIATE RADIO SYSTEM A J CA2. 2 50 239 coax sockets 2 Eight 8 46 32 pan head screws 3 One 1 foot of hook up wire PROCEDURE 1 Disconnect main power to the receiver 2 Place the receiver on a bench with the top removed and the rear panel facing you NOTE In the next step you will remove the module containing the antenna connectors It is important to clearly mark the BNC connectors J109 J110 J111 with tape or colored marking pens before removing the cables from the module 3 Locate the three 3 BNC connectors J109 J110 and 4111 on the module 4 Using a different color pen or tape mark each BNC connector and it s associated cable 8 URII EU ARMI MARS MILITARY AFFILIATE RADIO SYSTEM A J CARMODY AAR2QR W2LE MODULE REV REF PAGE S REMARKS NONE 20 177 418 ANTENNA INPUT CONV TO 50 OHMS 5 Disconnect the three 3 cables from the BNC connectors Locate the three 3 screws that hold the antenna module to the rear panel Remove and save the screws 8 Ihe module should now be free to remove from the rear panel Remove and save the two 2 screws that hold the cover on the antenna module 9 Solder a small jumper wire from the center of J110 to ground NOTE In the next step you will remove the BREAK IN RELAY and it s associated hardware This feature has no effect on the performance of the receiver 10 Remove the two insulated wires going to the relay coil and tape the ends of the wire
3. 585 1S MINUS 10DB CR LESS NUON Uo no TEST FREQUENCIES 1 5 1 2 BAND 2 4 MC BAND Ru 8 BAND 12 8 16 MC BAND 24 OMG 16 32 MC BAND
4. D FIG 2 UNITED STATES ARMY MARS MILITARY AFFILIATE RADIO SYSTEM A J CARMODY AAR2QR W2LE MODULE REV REF PAGES REMARKS IF SUB CHASSIS 4 99 128 129 99 128 129 PURPOSE To replace ballast tube 3TF7 with a conventional vacuum tube REASON 1 Ballast tubes are hard to find and expensive 2 Other methods using power dropping resistors dissipate excessive heat under the chassis which is undesirable 3 Use of voltage regulators require more parts and are more costly 4 This method allows easy substitution of ballast tubes if you are lucky enough to find them TOOLS REQUIRED Wire strippers Set of Allen wrenches Phillips head screwdriver Soldering iron and solder Assortment of multi colored fiber tipped marking pens PARTS REQUIRED Three 3 inches 22 AWG PVC insulated hook up wire One 1 12BH7 or 12BY7 vacuum tube PROCEDURE 1 Disconnect main power to the receiver NOTE In the following step you will loosen two 2 shafts from the IF SUB CHASSIS to the controls on the front panel Before loosening tbe shafts it is important to note the position of the BANDWIDTH knob and the BFO PITCH knob 2 Using an Allen wrench loosen the set screw on each Oldham coupler which secures each shaft from the front panel controls to the IF SUB CHASSIS 3 Disconnect the power plug to the IF SUB CHASSIS 3 UNITED STATES ARMY MARS MILITARY AFFILIATE RADIO SYSTEM
5. NITED STATES ARMY MARS MILITARY AFFILIATE RADIO SYSTEM CARMODY AAR2QR W2LE MODULE REV REF 5 AF SUB CHASSIS 97 98 99 131 7 Set the AF subchassis on a bench with the bottom of the tube sockets facing you NOTE There are several large holes in the chassis around the base of the octal tube sockets to provide air circulation We will use one of these holes to mount the stud diode 8 Mount the stud diode in one of the chassis holes Select amp hole between the octal tube sockets If the hole is larger than the stud use flat washers from your junk box Be sure to coat the flat base of the stud diode with heat sink compound Also apply a thin coat of compound to the flat washers 9 Wire the circuit refering to Fig 2A and 2B v606 Vv605 _ __ 606 605 8 BLK MODIFIED BLK FIG 4 FIG 2B BLK WHT UNITE 310IATCO ANMI MARS MILITARY AFFILIATE RADIO SYSTEM A J CARMODY AAR2QR W2LE MODULE REV REF PAGE S REMARKS NONE 20 81 82 8 LOW IMPEDANCE SPKR CONNECTION The R 390 receiver has two 2 audio channels LOCAL AUDIO and LINE AUDIO with seperate gain controls for each channel The output impedance of each channel is 600 ohms The LINE AUDIO channel s intended to be used as a balanced audio line The LOCAL AUDIO channel is to be used for speaker and headphones The R 390 receiver does not have a self contained speaker Therefore it is necessa
6. R CONVENIENT LEVER SIGNAL PLUS RCVR NOISE NE DE TUNE RECEIVER FROM TEST SIGNAL AND MEASURE RE CEIVER NOISE 5 A DIFFERENGE OF 20DB BETWEEN SIGNAL PLUS RECEIVER NOISE AND RECEIVER NOISE INDICATES A GOOD R 390 RECEIVER STANDARD AUDIO SIGNAL OUTPUT GENERATOR RECE IVER METER AN URM 25 R 390 URR TS 585 U TEST SIGNAL RF INPUT OUTPUT 10 MICROVOLTS A LOCAL pev sd sm e IAE OUTPUT 4 330 OHM CABLE ES Ram 2 50 OHM 56 70 OHM ORM OH CMM CU 4 08 URM 25F IMPEDANCE MATCHING NETWORD AND 10 1 VOLTAGE DIVIDER NOTE CU HOB URM 25F 15 SUPPLIED W URM 25F MODEL ONLY FOR URM 25D AND OTHER MODELS CHANG RESISTORS AND CIRCUIT IN EITHER 5 1 OR 10 1 ATTENTUATORS TO AGREE W CU 408 CIRCUIT AS SHOWN ABOVE PROCE LURE 1 SET RECEIVER CONTROLS FOR CV RECEPTION A BANDWIDTH 2KC B AUDIO RESPONSE WIDE C BFO PITCH ZERO D LIMITER OFF ee R37 FUNCTION MGC RF GAIN MAX TUNE RECEIVER TO ZERO BEAT WITH TEST SIGNAL TURN BFO PITCH TO MINUS 1 OR PLUS 1 PEAK ANTENNA TRIMMER FOR MAXIMUM INDICATION ON ADJUST RF GAIN FOR PLUS 10 DE TUNE RECEIVER LEAST 10KC FROM TEST SIGNAL FREQUENCY 75 585 NOW INDICATES RECEIVER NOISE OUTPUT RESULTING FROM STANDARD GAIN SETTING ESTABLISHED BY STEP FIVE ABOVE RECEIVER PASSES TEST IF NOISE INDICATION ON TS
7. RMODY AAR2QR W2LE MODULE REV REF PAGE S REMARKS AF SUB CHASSIS 91 98 9911 _ PURPOSE To replace the 6082 2 volt fil regulator tubes which are expensive and hard to find with 6080 6 volt fil tubes NOTE 6AS7G tubes are electrically similiar to the 6080 but are too large to fit into the R 390 TOOLS REQUIRED Phillips head screwdriver Soldering iron and solder Wire strippers Diagonal cutters Nut driver set or small socket set PARTS REQUIRED Power diode stud mounted with mounting hardware 1N1183 35 amp 50 PIV or equivalent Three feet 20 AWG or larger PVC insulated hook up wire Thermal heat sink compound available at Radio Shack stores NOTE The original filament circuit of the two 2 regulator tubes V605 and V606 is wired in parallel In this modification the filament circuit will be connected in series as indicated in Eig 1 Polarity of the diode doesn t matter Just be sure the mount ing stud is securily fastened to the sub chassis for heat sinking purposes PROCEDURE 1 Disconnect main power to the receiver 2 Locate the two regulator tubes V605 and V606 on the AF sub chassis 3 Remove the holding rings and the regulator tubes from their sockets Disconnect the two 2 power plugs from the AF sub chassis 5 Locate the GREEN phillips head captive screws Loosen them completely 6 Grasp the AF sub chassis gently removing the unit from the chassis V605 V606 U
8. THE R 390 COOKBOOK BY A CARMODY W2LE AAR2QR PREFACE The R 390 COOKBOOK was intended to be used in conjuncti n with the R 390 URR Service Manual However sufficient information is provided so that each modification can be accomplished without the aid of the Service Manual These modifications have been incorporated into several receivers with excellent results The Author however assumes no responsibility for the operation of these circuits Carmody September 1983 Copywrite 1983 Empty Cloud Canandaigua N Y All rights reserved CONTENTS ITEM PAGE POWER SUPPLY SUB CHASSIS MODIFICATION 1 2 IF SUB CHASSIS MODIFICATION 3 h AF SUB CHASSIS MODIFICATION 5 6 LOW IMPEDANCE SPEAKER CONNECTION 7 ANTENNA INPUT CONVERSION TO 50 OHMS 8 9 UNITED STATES ARMY MARS MILITARY AFFILIATE RADIO SYSTEM A J CARMODY AAR2QR W2LE MODULE REV REF PAGE S POWER SUPPLY SUB CHS 295 96 PURPOSE To convert the power supply from vacuum tubes 2625W to solid state diodes REASON 1 Replacement tubes hard to find 2 Eliminate heat from vacuum tube rectifiers 3 Improve reliability with solid state diodes TOOLS REQUIRED 1 Long phillips head screwdriver 2 Soldering iron and solder 3 Diagonal cutters Long nose pliers PARTS REQUIRED Two 2 1NLOO7 diodes 1000 PIV 1 amp or equivalent PROCEDURE 1 Disconnect main power to the receiver 2 Remove tube shields and 26Z5W vacuum tubes fro
9. m the power supply 3 Disconnect the power plug to the POWER SUPPLY SUB CHASSIS Using the phillips screwdriver remove the four lj screws that hold the transformer to the side panel of the MAIN CHASSIS NOTE In the next two steps you will loosen three 3 captive screws which hold the power supply to the chassis 5 Locate the GREEN phillips head screw adjacent to the tube socket and loosen it completely 6 There are two 2 locating holes in the top of the POWER SUPPLY SUB CHASSIS bracket Below each hole is a GREEN phillips head screw Loosen both of these screws completely 7 Grasp the POWER SUPPLY SUB CHASSIS and remove it from the receiver _ ____ __________ _ _____ _______ _ _ __ __ _ _ __ _ ____ ____ ___ _____ ________ __ _____ __ ___ _ 1 UNITED STATES ARMY MARS MILITARY AFFILIATE RADIO SYSTEM 2 CARMODY AAR2QR W2LE REV REF PAGE S 8 Place the POWER SUPPLY SUB CHASSIS on a bench with the bottom of the tube sockets facing you NOTE When installing diodes it is important to observe their polarity See Fig 1l 9 Install a diode on socket XV801 the cathode lead banded end soldered to Pin 3 10 Solder the anode lead to XV801 Pin 6 11 Install a diode on socket XV802 the cathode lead banded end soldered to Pin 3 12 Solder the anode lead to XV802 Pin 6 THIS COMPLETES MODIFICATION OF THE POWER SUPPLY SUB CHASSIS ANODE LEAD CATHODE LEA
10. ry to provide an external speaker Most speaker impedances are low typically 4 to 16 ohms Since the LOCAL AUDIO output impedance of the receiver is 500 ohms if we wish to connect a low impedance speaker to the receiver an audio impedance matching transformer must be used A filament transformer from the Junk box will work but has poor high frequency response Radio Shack TM stores offer a 70V Line Transformer stock number 32 1031 for under 5 00 which works very well It s secondary is tapped for 4 8 16 ohms and has solder lug terminals Connect the high impedance primary of the transformer to TB2 6 and TB2 7 located on the rear panel of the receiver Refer to Fig 1 for proper connections FIG 1 REAR PANEL R 390 RECEIVER SPKR XFMR 7 UNILEU ARMI MARS MILITARY AFFILIATE RADIO SYSTEM CARMODY AAR2QR W2LE MODULE REV REF PAGE S REMARKS NONE I2 ANTENNA INPUT CONV TO 50 OHMS PURPOSE To replace antenna input connectors with S0 239 connectors that mate with standard ham equipment Change antenna input from a balanced line to an unbalanced line REASON Adapters or C type connectors are difficult to locate and are non standard ham equipment Most ham stations use 50 ohm unbalanced coaxial line TOOLS REQUIRED 1 Phillips head screwdriver 2 Colored marking pens Soldering iron and solder Long nose pliers 5 Wire strippers 6 6 32 tap PART3 REQUIRED 1 Two
11. s 11 Remove the relay from the antenna module 12 Unsolder all wires going to the antenna connectors J107 J108 13 Using a screwdriver remove both antenna connectors J107 J108 24 Remove any wires going to the center of J109 and 2111 NOTE In the next step you will put threads in the four mounting holes of each 50 239 connectors 15 Locate the 50 239 antenna connectors and thread the four 4 mounting holes of each connector using the 6 32 tap 16 Install one of the 50 239 connectors at J107 UNBALANCED WHIP such that the connector is inside the antenna module 17 Solder a small piece of hook up wire from the center of J107 to the center of J109 18 Similiar to STEP 16 install the remaining S0 239 connector at J108 19 Solder a small piece of hook up wire from the center of J108 to the center of 7111 20 Replace the cover on the antenna module 21 Install the antenna module in the receiver 22 Reconnect the three 3 cables to the BNC connectors I ve found it convenient to connect a second receiver s antenna input to J107 using a short cable and connect my main antenna to J108 so that the two receivers share the same antenna 9 TESTING R 390 URR RECEIVERS DESCRIPTION OF TEST 1 APPLY ONE MICROVOLT GW TEST SIGNAL TO RECEIVER INPUT 2 TUNE RECEIVER FOR ZERO BEAT BETWEEN TEST SIGNAL AND BFO AT CENTER OF IF BANDPASS 3 ADJUST RECEIVER CAIN FOR AN AUDIO OUTPUT OF PLUS 10DB OR OTHE
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