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JJJelectronics-3 band direct conversion receiver-v1

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The JJJelectronics direct conversion receiver -v1 is an amateur radio receiver in kit form .It covers the 40m and 80m with provision to add additional frequency bands by means of plug-in modules.

The DC receiver -v1 is a direct conversion receiver suitable for SSB and CW

Technical details

Frequency band 80m (3.5MHz -3.85MHz), 40m (7.0MHz -7.11MHz) ,Plug in modules can be used to give additional bands

Frequency tuning: separate FET VFO for each band with voltage stabilised feed to oscillators.

Mixer: MC1496 integrated circuit double balanced mixer.

Audio 2500Hz SSB filter and 700Hz CW filter (push button switch to switch between them) employed with audio output of up to 1W into 8-Ohms speaker.

Power required 11.5v to 14v DC.

Protection diode for wrong polarity

. Tool required.

Soldering iron (25w-40w), small cutter, and trimming tool for oscillators and filters coils.

Let’s build the receiver

I would recommend fitting the parts in the order they appear in the part list.

Resistor first, then semiconductors, fixed coils, Capacitors and variable coil.

Make sure you put the electrolytic capacitors and diodes in the right way round .keep all components leads as short as possible.

When you have finished assembly of the board, check all the parts are in the right places.

The soldering looks bright and good. Re-solder any suspect joints with a little fresh solder, check that there are no short or splashes of solder between tracks.

Resistors

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R1 4k7 yellow -purple –red R18 1k brawn – black - red

R2 150R brawn- green- brawn R19 33k orange- orange-orange

R3 4k7 yellow -purple- red R20 33k orange- orange-orange

R4 27R red -purple –black R21 2k2 red -red -red

R5 100k Brawn -Black –yellow R22 820R grey -red -brawn

R6 4k7 yellow -purple –red R23 1k brawn – black - red

R7 150R brawn- green- brawn R24 390R orange-white-brawn

R8 4k7 yellow -purple –red R25 2k7 red -purple –red

R9 27R red -purple –black R26 390R orange-white-brawn

R10 100k Brawn -Black –yellow R27 2k2 red -red -red

R11 2R7 red- purple-gold R28 8k2 grey – red - red

R12 3k3 orange – orange - red R29 1k2 brawn – red - red

R13 3k3 orange – orange - red R30 2k7 red -purple –red

R14 10k brawn – black – orange R31 47R yellow-purple-black

R15 12k brawn- red-orange R32 47R yellow-purple-black

R16 12k brawn- red-orange R33 1k5 brawn – green - red

R17 270k red –purple –yellow R34 47R yellow-purple-black

R35 3k3 orange – orange - red

Transistor, Diode and IC

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Q1 BF245

Q2 BF245

T1,T2,T3,T4 2N2222

They should be installed in the board as the outline printed on the board shows

IC1 MC1496

IC2 LM380

IC4 78L09 9v regulator, the shape is like transistor shape. It should be installed in the board as the outline printed on the board shows

IC5 TL074

All ICs should be installed in the board as the outline printed on the board shows

D1 1N4001 (black colour with white line)

D3, D4, D7, D8, D9, D10 1N4148 (glass with black line)

Please check the polarity of each diode, they should be installed in the board as the outline printed on the board shows

Coils

L1 variable inductor A110TK

L2 variable inductor A530TK

L5 variable inductor A9C21TK

L10 variable inductor A9C21TK

L11 220uh red – red – brawn

L12 Binocular ferrite core- see the text

Capacitors

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C1 10nf marked 103

C2 100pf marked 101

C3 100nf marked 104

C4 22nf marked 223

C5 100nf marked 104

C6 10nf marked 103

C7 10nf marked 103

C8 10nf marked 103

C9 100nf marked 104

C10 see text NP0 capacitor for oscillator only ,see text

C11 see text NP0 capacitor for oscillator only ,see text

C12 see text NP0 capacitor for oscillator only ,see text

C13 10nf marked 103

C14 180f marked 181

C15 100nf marked 104

C18 10nf marked 103

C19 10nf marked 103

C20 100nf marked 104

C21 see text NP0 capacitor for oscillator only ,see text

C22 see text NP0 capacitor for oscillator only ,see text

C23 see text NP0 capacitor for oscillator only ,see text

C24 10nf marked 103

C25 100uf/25v marked 100uf

C26 220uf/25v marked 220uf

C27 100nf marked 104

C28 100nf marked 104

C29 22uf/63v marked 22uf

C30 1uf/63v marked 1uf

C31 22nf marked 223

C32 10nf marked 103

C33 47nf marked 473

C34 10nf marked 103

C35 100nf marked 104

C36 1nf marked 102

C37 1uf /63v marked 1uf

C38 100nf marked 104

C39 4.7nf marked 472

C40 4.7nf marked 472

C41 47nf marked 473

C42 10nf marked 103

C43 100nf marked 104

C44 10nf marked 103

C45 4.7nf marked 472

C46 10nf marked 103

C47 10nf marked 103

C48 100uf/25v marked 100uf

C49 100nf marked 104

C50 47uf/25v marked 47uf

C51 47uf/25v marked 47uf

C52 100nf marked 104

C53 100nf marked 104

C54 100nf marked 104

C55 100nf marked 104

C56 1uf/ marked 1uf

VC1 module ( variable capacitor 60pf )

C25, C26, C29, C30, C37, C48,C50,C51 and C56 are electrolytic capacitors and must be installed the correct way round. The Longest lead is normally positive, this lead should go to the hole marked “+“on the circuit board.

Miscellanies

VR1 -------1Kvariable resistor

VR2 ------ 10K variable resistor

Two DPDT switches (SW1 and SW2)

Rotary switch

Kit come with 16x pins terminal, 4 way connector and 5 way connector.

J3 is jumper (linked wire) you have to solder a piece of wire between J3 holes

J4 is jumper (linked wire) you have to solder a piece of wire between J4 holes

ANT and GND are for antenna cable ,the ANT-IN should go to the center of the BNC connector and the GND pin terminal should go to the ring terminal of the BNC connector

The frequency counter(not supplied) has 4 pins two of them are for power, marked as +12v and GND ,these 2 pins should go to the +12v and GND in the main board. the other 2 pins from frequency counter are for input ,one of them marked input ,this should go to the FC in the main board and the other pin from frequency counter (GND ) should go to the GND in the main board

On the PCB there are two holes marked SP1, SP2, they are for speaker (not supplied) any speaker between 1w and 2w will be fine

Binocular ferrite core

You have to make 2 coils

Wind 8 turns of the thin enamelled yellow wire tightly onto the two holes balun core. Passing the wire through one hole and then back out of the other counts as one turn. Do this 8 times for eight turns. Both ends of the wire should project from the same side as shown.

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Wind 2 turns of the enamelled red wire as shown.

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You have to remove the varnish from the enamelled wire ends ,you can use fine sandpaper or you can use hobby knife.

L12 is the Binocular ferrite core it has 4 holes ,the yellow coil should go to holes 2 and 3,

The red coil should go to holes 1 and 4

Assembling

After you assembled the board with all components and pin terminals:

1: fit 4 spacers m3 x5mm and four m3x4mm screws to the chassis as shown below

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2: add M8 lock washer to the variable resistors as shown below :

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3: fit the board to the chassis ,use four m3x4mm screws as shown below:

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4: fit two M7 nut to the variable resistor and fight them as shown below:

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5: solder wires to the rotary switch as shown below make sure to solder the right wire colour to the right number for the rotary switch

A = blue , B = Green , 1= purple , 2 = pink , 3 =brown , 4 =yellow , 5 = orange , 6 =gray

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6: After you soldered the rotary switch ,add M12 washer to the switch and fit it to the chassis ,use the nut that came with it and tight as shown below:

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7: now solder the wires from rotary switch to the board ,make sure the wires are not too long and away from the variable capacitor module as shown .

A, Blue colour to S

B, Green to the side pin of variable capacitor (not middle terminal)

1, Purple to the S2

2, Pink to the S1

3, Brown to the S3

4, Yellow to the VC2

5, Orange to the VC1

6, Gray to the VC3

use white wire , solder it from variable capacitor (middle terminal to the board,GND as shown

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8: fit the BNC connector ,earphone connector and power connctor (use M3x10mm screws with M3 nuts) as shown

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9: solder SP1 (gray colour to the top terminal of earphone and solder SP2 (green colour to the side terminal of the earphone as shown

Note: it is very important not to swap between SP1 and SP2 ,please follow the photo, if you swap them you will damage the audio amplifier IC (LM380)

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10: connect the BNC connector as shown below

Ant-in, to the center of the BNC (purple colour) and GND to the other BNC terminal (black colour)

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11:solder red wire from the +12v terminal (on the board) to the red terminal of the power connector and solder the black wire ,GND terminal (on the board) to the black terminal of the power connector as shown below

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Testing

You need a frequency counter

Connect the frequency counter to the pin terminal marked FC on the PCB

FC connector should go to input (number 1) of frequency counter and the second pin of the frequency counter (pin 2) should go to pin terminal marked GND on the PCB.

You will need to adjust the oscillator coils (L10 and L5) to set the exact frequency coverage of the radio.

You must use a proper insulated trimming tool to adjust the cores of the coils.

Use the frequency counter (not included with the kit), you can read the receiver frequency directly.

To adjust the 80m band, put the rotary switch to 80m.

Turn the tuning capacitor clock wise (minimum reading) adjust L10 until you get about 3.50MHz

Now turn the tuning capacitor to the maximum and you should get around 3.85MHz

To adjust the 40m band, put the rotary switch to 40m.

Turn the tuning capacitor clock wise (minimum reading) adjust L5 until you get about 7.0 MHz

Now turn the tuning capacitor to the maximum and you should get around 7.14MHz

Connect antenna and adjust L2 for 80m, for minimum noise (normally the core will be down to the end

Adjust L1 for 40m, for minimum noise (normally the core will be down to the end

Adding additional channel

SV3 and SV5 are PCB mounting plugs and form the connectors for the optional plug-in band modules. Insert the plug-in module (not supplied) to SV3 and SV5 .change the rotary switch to ch3 position and follow testing procedure as above

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Adding frequency counter

Mount the frequency counter to the 3 bands receiver (use M2.5x6 screw ,supplied with frequency counter)

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1 :Solder 2 wires black and red to the input of frequency counter (red to pin number 1 and black to pin number 2).

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2:Solder the red wire to the FC terminal on the receiver and solder the black wire to the GND on the receiver .

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3: now solder another 2 wires (red and black)

From frequency counter +12v to the IC4 on the receiver and solder black wire from frequency counter ,GND to the GND of the receiver as shown

Make sure not to make any short to the IC4

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If you need any help email me, jjjelectronickit@yahoo.co.uk

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