Marconi Basic-7B Assembly Manual

8/9/2019 Marconi Basic-7B Assembly Manual

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Marconi Basic-7B Assembly Manual

www.marconi-japan.com

01/05/2010



1. Tools & Supplies

You will need:

30W soldering iron with a narrow tip.

Soldering iron holder with a moistened

cleaning sponge.

Board

60/40 alloy solder.

Desoldering braid.

Scotch tape

Small needle-nose pliers.

Diagonal cutters

Screw drivers.

Cutter Tester.

Receiver or frequency counter.

12V @250mA regulated DC power source or

dry batteries.

Telegraph key.

Antenna.

Tools are below.

Frequency of VXO is checked by a receiver.

Frequency counters are useful.

You will need a Power Supply.

Or a 12volt 1.2AH Battery.

You will need a telegraph key.

You will need an antenna.

A dipole antenna is recommended



2. Parts Inventory

Packages are below.

Place small parts onto the check list and then tape

them to in place to make sure you have all of the

parts.

Parts Check List (1)




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3. Practice of soldering

3-1 Making Dummy Load

Solder a 51 resistor on a back of fem

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le terminal.

Bend the leads to finish th

3-2 Making RF Probe

Solder two diodes as in th

Use diagonal cutters to hol

Solder two disc capacitors

Cut the wires. Short wire

long. Long black wire is 5 1

Take off vinyl film.

1W dummy load.

schematic.

d small parts.

as in the schematic.

are 2 1/2 inches (60mm)

/2 inches (140mm) long.



Solder the wires on terminals of alligator clips.

Solder them together to finish the RF Probe.

4. Installing Stabilizers

Install four long bolts into the holes of the PCB to

stabilize PCB while soldering.

4/10 inches (10mm) in depth

5. Inserting Terminals

Insert the 24 male terminals into the holes of PCB with

pliers.

12VDC = 2

KEY & RIT = 5

VC = 2

CHECK POINT = 2

AF-GAIN = 3

PHONES & SP. = 5

ATT & ANT. = 5

Solder the terminals on the PCB.



6. Assembling DC power supply port

6-1 DC Connecter & SwitchCut the wires. Long wires are 4 inches (100mm) long.

Red short wire is 2 1/2 inches (60mm) long.

Solder the parts.

Connect the terminals.

6-2 DC plug cableParts

Solder the wires on the connecter.

6-3 TestingSupply plus 12 volts and check the voltage at the

terminals with a tester. The final transistor will be

destroyed if you supply minus 12 volts.

Use a pair of pliers to insert and remove the

terminals.

Insert

remove



7. Assembling TR switch

7-1 TR switchSolder the parts on the PCB.

Solder 15k ohm to improve timing.

7-2 Key Jack cableCut the wires 4 inches (100mm) long.

Solder the female terminals and a stereo jack.

7-3 Key plug cableParts.

Solder the wires and stereo plug.

CautionA stereo jack and monaural jack are very similar.

A monaural jack has a switch inside.

A stereo jack does not.



Connect a key.

7-4 Testing

Connect a key to the PCB and supply 12 volts.

Check the voltage at the emitter of Q6.

It will be about 12 volts.

Push down the key.

The voltage will get lower than 0.5 volts.

Check the voltage at the collector of Q5.

It will be about 0.001 volt.

Push down key. The voltage will get about 12 volts.

Use Diagonal cutters and scotch tape to hold

parts while soldering.



8. Assembling VXO

8-1 VXOSolder the parts on the PCB.

8-2 Variable Capacitor cableCut the wires 2 inches (50mm) long and take off vinyl

film.

Solder the parts.

8-3 RIT Potentiometer cableCut the wires 7 inches (170mm) long.

Solder the parts.

8-4 Adjusting VXO FrequencyInstall the VC and the potentiometer to the PCB.



Connect the PF Probe, the key and supply 12 volt.

Connect the RF Probe at the CHECK POINT.

Turn the potentiometer anticlockwise to stop RIT.

Tune T2 and T3 at oscillating frequency.

RF Probe will show about 6mA at peak.

Tune T1 and adjust the width of variable frequency.

Use a receiver to check the frequency. The core is at

ceiling, VXO oscillates 7.020~7.040MHz. The core is

at bottom, VXO oscillates 6.990~7.033MHz.

The VC capacitor is full and T1 is tuned at 7.000MHz,

VXO oscillates 7.000~7.035MHz.

Turn the potentiometer clockwise to work RIT.

Push the key down to stop RIT.

Use scotch tape to hold a IC and a jumper wire

while soldering.



9. Assembling Driver

Solder the parts on the PCB.

10. Assembling RF POWER AMP.


Making L1Insert the enameled 0.32mm diameter wire into

the hole of ferrite bead to hold with fingers.

Hold the wire and wind the wire 10 turns.

Count up to 10.

1

2

3

10

Take off enamel film with sandpaper.

Pre-solder the wire.



11. Assembling Low Pass Filter


12. Testing Transmitter

Connect Power Supply, key, Dummy Load, and RF

probe. T4 is broad. It is not necessary to tune T4.

Dummy load and RF probe is at ANT terminal.

Push the key down in short time.

DC current will be over 100mA.

Making L2 & L3Insert the enameled 0.4mm diameter wire into the

hole of toroidal core to hold with fingers.

Hold the wire and wind the wire 19 turns.

Take off enamel film with sandpaper.

Pre-solder the wire.

The final transistor 2SC2053 will overheat and be

destroyed if you hold the key down too long.



13. Assembling AF Power Amp.

13-1 AF Power Amp.Solder the parts on PCB.

Solder 1.2k ohm as in the schematic to decrease the

gain from 200dB to 80dB when you want to do it.

13-2 LM386 Jumper wireCut red wire 7 inches (170mm) long.

Insert the wire into +T/R holes and solder them.

13-3 AF GAIN Potentiometer cableCut the wires 4 inches (100mm) long.

Solder female terminals,wires,and a potentiometer.

13-4 PHONES jack cableCut the wires 5 inches (120mm) long.



Solder them.

13-5 SPEAKER cableCut the wires 18 inches (450mm) long.

Solder wires and a speaker.

13-6 Testing AF Power Amp.Connect Power Supply, speaker, jack, potentiometer.

Turn the potentiometer clockwise.

Touch the AF-GAIN terminal with a finger to check the

circuit. It makes noise when the circuit works.



14. Assembling AF Preamp.

Solder the parts.

15. Assembling SBM

Solder the parts.

16. Assembling RF Amp.

16-1 RF Amp.

Solder the parts.

Solder D8 and D9 as in the schematic.

Solder 2 7/10 inches (70mm) jumper wire as in the

schematic.



16-2 RF Amp. Jumper wire.Cut white wire 4 inches (100mm) long.

Insert the wire into +R holes and solder them.

16-3 ATT Potentiometer cable.Cut the wires 4 inches (100mm) long.

Solder them.

16-4 ANT. cableParts.

Solder the parts.

16-5 Testing Receiver Connect the modules to the PCB & supply 12 volts.

Tune T5 & T6. Do not touch T7. It is a transformer not

at resonance. The core of T7 is very weak.


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17. Assembling SIDETONE

17-1 SIDETONESolder the Parts.

17-2SIDETONE jumper wireCut yellow wire 5 1/2 inches (140mm) long.

Insert the wire into +T holes and solder them.

17-3 Testing SIDETONEConnect the modules to the PCB and supply 12 volts.

Do not forget to install the Dummy Load at the ANT

terminal or you will destroy the final transistor.

Tune the volume with VR2.

18. Completion

Marconi Basic-7B Assembly Manual

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