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EA3GCY DB4020, Assembly Manual

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DB4020 Dual Band 40&20M SSB QRP Transceiver Kit 

Page 1 

 

DB4020 

Dual Band 40&20m QRP SSB transceiver 

KIT 

Assembly manual 

Last update May 20, 2020 

 

[email protected]

 

Latest updates and news in

: 

www.ea3gcy.com 

 

 

 

Thank you for building the 

DB4020

 

Dual Band 40&20M SSB Transceiver kit 

Have fun assembling it and enjoy QRP!   73 Javier Solans, ea3gcy 

Summary of Contents for DB4020

Page 1: ... Band 40 20m QRP SSB transceiver KIT Assembly manual Last update May 20 2020 ea3gcy gmail com Latest updates and news in www ea3gcy com Thank you for building the DB4020 Dual Band 40 20M SSB Transceiver kit Have fun assembling it and enjoy QRP 73 Javier Solans ea3gcy ...

Page 2: ...ON 3 SPECIFICATIONS 4 TIPS FOR FIRST TIME BUILDERS 5 PARTS LIST SORTED BY VALUE QUANTITY 7 INDIVIDUAL PARTS LIST 9 240 QUADRANT COMPONENT LAYOUT MAP 13 ASSEMBLY 14 ADJUSTMENT AND TESTING 28 IF YOUR KIT DOES NOT WORK AFTER COMPLETING ASSEMBLY 32 LIMITED WARRANTY 33 SCHEMATIC 34 WIRING 35 ...

Page 3: ... Tuning Volume and RF attenuator In addition to tuning all the functions of the controller are carried out by means of the rotary encoder with push button no more keys or push buttons The DB4020 is a single board design in which all the elements are included CW mode is possible by means of a CW Interface module and a pluggable narrow IF filter optional The DB4020 kit uses through hole components y...

Page 4: ...dimensions 180 x 140 mm Weight no enclosure 0 28 kg TRANSMITTER Emissión SSB CW optional RF output 8 W on 40m 4W on 20m 13 8V 2nd harmonic output 45dBc or better below the fundamental frequency Other spurious signals 50dBc or better below the fundamental frequency Carrier suppression better than 40dBc T R switching Relays Microphone type Electret condenser capsule included RECEIVER Type Superheter...

Page 5: ...rmostatically controlled Use only solder intended for electronic soldering NEVER use extra flux You should hold the hot soldering iron in contact with both the circuit board and the component lead for about two seconds to heat them up Then keeping the soldering iron in place touch the solder at the junction of the component lead and circuit board trace and wait about two seconds or so until the so...

Page 6: ... body of the capacitor Make sure that the positive lead of the capacitor goes through the hole marked with a on the circuit board Toroids You may find it convenient to wind and prepare all the toroids before beginning to mount the components That way you won t have to stop and possibly lose concentration while winding them This is the part of the construction that some consider to be the most diff...

Page 7: ...0K P6 adjustable trimmer 104 1 1K P3 potentiometer 1K B1K 1 10K P5 potentiometer 10K B10K 1 Encoder Rotary Encoder PEC16 2015F Capacitors list Qty Value Checked Ref Identified 8 1n C2 C5 C18 C20 C21 C22 C55 C78 102 or 0 001 4 10n C26 C27 C30 C81 103 or 0 01 43 100n C6 C8 C9 C15 C16 C19 C23 C24 C28 C29 C31 C32 C33 C34 C49 C50 C52 C53 C54 C56 C58 C59 C61 C63 C69 C70 C72 C73 C74 C75 C79 C80 C84 C86 C...

Page 8: ... 1u2H L4 L5 1u2 or 1R2 2 5u3H L2 L3 5u3 or 5R3 2 100uH L1 L7 brown black brown 3 T37 2 L9 L10 L11 Red toroid 3 T37 6 L12 L13 L14 Yellow toroid 2 FT37 43 L6 L8 Black toroid 8 4 915MHz 4 915MHz crystals 4 915 or 4 91 1 12VDPDT Relay RL1 Huigang HRS2H 12V 7 OMRON G5V 1 12V RL2 RL3 RL4 RL5 RL6 RL7 RL8 Omron G5V 1 12V Connectors and Hardware Qty Value Checked Ref Identified 1 BNC socket BNC PCB socket ...

Page 9: ...r to Q3 screw 2 M3x10 screw 10mm M3x10 screw to Q3 and Q2 4 M3x4 screws 4mm M3x4 screws 6 M3 nuts M3 nuts 2 M3 washer Metal M3 washer to Q2 and Q3 4 M3 spacers Hex 5mm M3 spacers 217 217 cms 217 cms 0 5mm enamelled wire 1 Microphone Electret Microphone Capsule 1 PCB DB4020 PCB printedcircuitboard DB4020 ...

Page 10: ...GC D 10 R24 1K brown black red AGC E 10 R25 100K brown black yellow AGC F 10 R26 100K brown black yellow AGC F 10 R27 100K brown black yellow AGC F 11 R28 220K red red yellow AGC F 11 R29 22 Ω red red black IC4 supply L 9 R30 470 Ω yellow violet brown IC4 and IC5 supply K 9 10 R31 22 Ω red red black IC5 supply M 10 R32 1K brown black red SSB Dem N 11 R33 1K brown black red Audio preamp M 11 R34 10...

Page 11: ...104 or 0 1 IC1 an d IC2 supply K 1 C10 33p 33 or 33J IF xtal filter O 4 C11 33p 33 or 33J IF xtal filter N 4 C12 33p 33 or 33J IF xtal filter N 6 C13 33p 33 or 33J IF xtal filter M 6 C14 33p 33 or 33J IF xtal filter M 5 C15 100n 104 or 0 1 TX mix M 6 C16 100n 104 or 0 1 IC2 supply K 5 C17 220p n22 or 222 or 221 TX mix K 6 C18 1n 102 or 0 001 Pre driver L 5 C19 100n 104 or 0 1 Pre driver K 5 C20 1n...

Page 12: ... 0 1 Audio preamp M 11 12 C75 100n 104 or 0 1 Audio preamp M 11 C76 10uF 10uF electrolytic Audio preamp L 11 C77 10uF 10uF electrolytic Audio preamp K 12 C78 1n 102 or 0 001 Audio preamp J 11 C79 100n 104 or 0 1 S Meter path J 12 C80 100n 104 or 0 1 Audio Amp path J 12 C81 10n 103 or 0 01 Audio Amp L 12 C82 10uF 10 uFelectrolytic Audio Amp K 13 C83 100uF 100uF electrolytic Audio Amp L 14 C84 100n ...

Page 13: ...13 Q10 BC557 8 BC557 or BC558 Band switch B 13 Q11 BC547 BC547 CW Mute C 12 IC s IC1 NE602 NE602 or SA602 SSB Gen N 3 IC2 NE602 NE602 or SA602 TX Mix L 5 6 IC3 78L05 78L05 AGC supply G 11 IC4 NE602 NE602 or SA602 RX Mix L 7 8 IC5 NE602 NE602 or SA602 SSB Dem N 10 IC6 UA741 741 Audio premp J K 11 IC7 LM386 LM386 Audio Amp L M 13 IC8 7809 7809 Arduino supply P 10 IC9 7805 7805 Arduino supply R 9 IC1...

Page 14: ...w toroid 20m LPF C 8 L13 T37 6 Yellow toroid 20m LPF D 8 L14 T37 6 Yellow toroid 20m LPF E 8 Relés RL1 RL1a b Huigang HRS2H 12V Power ant relay C D 3 RL2 RL2 Omron G5V 1 12V Mute N 13 RL3 RL3 Omron G5V 1 12V Band switch D 4 RL4 RL4 Omron G5V 1 12V Band switch D 8 9 RL5 RL5 Omron G5V 1 12V Band switch F 6 RL6 RL6 Omron G5V 1 12V Band switch J 5 RL7 RL7 Omron G5V 1 12V TX RX path F 8 RL8 RL8 Omron G...

Page 15: ...DB4020 Dual Band 40 20M SSB QRP Transceiver Kit Page 15 252 QUADRANT COMPONENT LAYOUT MAP ...

Page 16: ... RF attenuator and volume potentiometers respectively which should not be installed yet Refer to the parts list and select the first resistor R1 Bend the leads as close to the component body as possible otherwise they will not fit well into the holes and place them into the appropriate holes according to the component outline printed on the circuit board Be careful to avoid confusing the resistors...

Page 17: ...e diodes being careful to place them with the correct orientation There is a dark colored band on one end of each diode that corresponds to the component outline on the circuit board There are 15 1N4148 diodes they are normally orange in color with a black band and they have the type 4148 printed on the body Note that some diodes are mounted in a vertical position D1 and D6 are Zener diodes simila...

Page 18: ...ible C35 through C42 are polystyrene capacitors these are axial capacitors but they must be mounted in a vertical position see image The values which are in decade increments can be easily confused such as 100n and 10n so be sure to verify the numbers of their value before soldering them in place The electrolytic capacitors must be placed with the correct orientation the LONG LEAD goes in the hole...

Page 19: ...er and use one hand to insert and hold the header in place using a jumper placed on the header while you solder the pins to avoid burning your fingers Use your other hand to hold the soldering iron and move the board towards the solder to solder the headers in place If you have someone available to help you it will be much easier Place jumpers on the terminals J1 if you do not use an ON OFF switch...

Page 20: ...suitable magnifying glass to read the marked references printed on them Q2 BD135 Mount Q2 onto the heatsink as shown in the image Use a mica insulator sheet that you will find in the kit and trim it 1 2mm so that it seats well within the heatsink Q3 2SC1969 Mount Q3 TX power amplifier onto the heatsink as shown in the image This transistor is placed with a mica insulator sheet and also a heatsink ...

Page 21: ...d has a U shaped notch on one end indicating the end at which pin 1 of the IC is located There is a similar notch on one end of the sockets This should be oriented over the U notch outline on the circuit board Finally pin 1 of the IC is marked with a small dimple or dot this end of the IC should be oriented towards the notch in the IC socket or the U on the component outline Mount the sockets for ...

Page 22: ... to obtain the best filter quality The crystal housing should not touch the board place them slightly separated from the board at a distance of 0 5mm Note With a scrap piece of wire left you can solder the crystals housings to GND Relays Install relays RL1 to RL8 They can only be placed in one position Make sure that the body of the relay lies flat against the circuit board Shielded coils cans L2 ...

Page 23: ...ey follow the contour of the toroid and are as tight against the toroid as possible The turns should be evenly distributed around the circumference of the toroid Leave pigtails of about 10mm 0 70 Scrape off the enamel with a knife from the ends of the wire in order to solder the toroid onto the board For L10 cut about 30cm 12 of 0 5mm diameter enameled wire and wind twenty 20 turns Mount and solde...

Page 24: ...nd wind the L12 and L14 toroids with sixteen 16 turns Spread the turns evenly around the toroid and wind them tightly so that they follow the contour of the toroid and are as tight against the toroid as possible The turns should be evenly distributed around the circumference of the toroid Leave pigtails of about 10mm 0 70 Scrape off the enamel with a knife from the ends of the wire in order to sol...

Page 25: ... should be evenly distributed around the circumference of the toroid Leave pigtails of 10 20mm 0 70 Now take about 8 cm 3 5 of 0 5mm diameter enameled wire and wind three 3 turns on the other side of the toroid spacing the turns over the previous winding Leave pigtails of 10 20mm 0 70 Before inserting them on the circuit board use a knife or sandpaper to scrape off the enamel from the pigtails of ...

Page 26: ... of turns as well as to the direction of the winding L8 Toroid transformer L8 is an impedance matching transformer with a bifilar winding An FT37 43 black toroid with 9 5mm 0 375in outer diameter is used It has 8 8 turns Cut a 31 32cm 12 long piece of 0 5mm diameter enameled wire Bend the wire in half Twist it so that there are two twists per cm ...

Page 27: ...ugh the center of the toroid Spread the turns evenly around the toroid Cut the ends and separate the two windings Use a sharp knife to scrape the enamel off the ends that will be soldered The ends of the coils that we have made need to be prepared in this manner before soldering them into the board Using a multimeter in its ohm or continuity function locate and mark the ends identifying them as a ...

Page 28: ...tches outside the board Then see the section WIRING AND CONNECTIONS Now mount and solder the Rotary Encoder the P2 volume potentiometer marked B10K and the P4 Rx attenuator potentiometer marked B1K in their respective positions Mount and solder the antenna and power jacks phones and speaker jacks and the SPK HEAD EXT SPK MIX SPK switches Before mounting the external connection jacks you should cut...

Page 29: ...odule is vertically with the board as shown in the images IC11 OLED 1 3 display This is the display for the DB4020 It may be best not to place it to the end Before placing it you must think and be sure how to install the DB4020 in your enclosure The OLED display use a strip of 7 pins at right angles to solder the module onto the board When solder you can adjust the distance a little to match the f...

Page 30: ...Page 30 You may prefer to install the OLED display encoder and potentiometers outside the board Then see the section WIRING AND CONNECTIONS IC12 Arduino NANO Install the two 15 pin female strips and insert the Arduino UNO module as shown in the image ...

Page 31: ...uency in the 40m band see the section using the DB4020 With an antenna connected to the transceiver alternately adjust L2 and L3 until obtaining the maximum noise level in the speaker Now try to tune in a stable signal within the band and readjust L2 and L3 alternately until you hear it at the highest possible level Tune to any frequency in the 20m band see the section using the DB4020 With an ant...

Page 32: ...r the transmitter output with an oscilloscope with a 50 ohm load connected Adjust P2 to obtain the minimum level possible of residual carrier signal If you don t have access to an oscilloscope you may listen to the transmitted signal on a SSB CW receiver adjust P2 until you hear the least possible amount of carrier signal Keep in mind that with a receiver so close you will ALWAYS hear a weak resid...

Page 33: ...rophone for amateur radio or build your own mic The wiring is very simple Note about electret capsules The connections of all capsules have polarity and The it is joined to capsule housing You can build your own handheld microphone with the micro electret capsule included in the kit and a pushbutton for PTT Home made microphone Handheld microphone speaker optional from www qrphamradiokits com ...

Page 34: ...ttle amplification Take care that distortion or feedback does not occur in the transmitter CW Interface and CW IF narrow Filter option The DB4020 board and the Arduino controller are prepared for a CW Interface module and a narrow IF Filter board This is an optional kit that you can buy separately 40 and 20 meters Antennas To obtain a good performance of the DB4020 it is essential to use a specifi...

Page 35: ...ing in several bands with a 49 1 transformer Look end fed antenna on Google DB40320 User Manual The DB4020 transceiver is easy to use There is a User Manual where all the functions of the transceiver are explained The Arduino module is already programmed at the factory There are a few initial frequency settings that will help get you up and running However for each assembly some slight re adjustme...

Page 36: ...tact or components mounted in the wrong place If your kit does not work after final assembly please follow these steps in order Double check every step in the assembly manual the solder connections and correct component placement If you have access to instrumentation take measurements and follow the signal path of the circuits to diagnose what is happening and why Request another ham experienced w...

Page 37: ...n this documentation and used correctly according to all provided instructions It is your responsibility to follow all the instructions in the manual to identify all the components correctly and to use good workmanship and proper tools and instruments in the construction and adjustment of this kit REMEMBER This kit will not work as a commercially manufactured product however it can often give simi...

Page 38: ...DB4020 Dual Band 40 20M SSB QRP Transceiver Kit Page 38 SCHEMATICS ...

Page 39: ...DB4020 Dual Band 40 20M SSB QRP Transceiver Kit Page 39 ...

Page 40: ...ed on the board However you can wire the elements off the board with the following considerations in mind Rear panel elements You may prefer to install the jacks connectors switches outside the enclosure This is not critical you can wire them But if the cable to the antenna connector is longer than 1 2cm then use thin 50ohm coaxial cable RG174 or equivalent Front panel elements OLED display encode...

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