Kanga Products FOXX-3 Скачать руководство пользователя

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The Kanga Products FOXX-3 20m QRP Transceiver

Assembly Instructions

Stage 2: The keying circuit

When the FOXX-3’s Morse key is pressed several things happen. Transistor TR2 turns on, energising the relay> This
removes the positive supply fed to the crystal oscillator via the Rx offset control, and disconnects the detector (PA
Transistor) from the volume control. Transistor TR1 turns on, energising the key +12v rail. This applies power directly
to the crystal oscillator (not via the offset control) to the PA transistor and to the sidetone oscillator so that the
Morse code being transmitted can be heard in the headphones. The voltage across the relay coil turns on TR3 to
mute the audio amplifier’s receiver input. When the key is released between the elements of Morse characters (Dits
and Dahs), the sidetone oscillator and crystal oscillator stop running but the relay is kept energised by the charge on
capacitor C13. If the key remains released for more than about half a second, the relay contacts change back to the
receive position. This time can be adjusted by altering the value of R6. The charge on C15 holds the mute transistor
on until the relay contacts have changed over.

Part Type

Markings

Notes

1KΩ

Brown, Black, Red, Gold

4k7Ω

Yellow, Violet, Red, Gold

10KΩ

Brown, Black, Orange, Gold

100KΩ

Brown, Black, Yellow, Gold

1KΩ

Brown, Black, Red, Gold

C11

100nF

104

C12

100nF

104

C13

10µf

10µF 16v

Electrolytic Capacitor-Observe polarity

C14

100nF

104

C15

10µf

10µF 16v

Electrolytic Capacitor-Observe polarity

C16

10nF

103

C17

100nF

104

1N4148 1N4148

Diode - Observe polarity

1N4148 1N4148

Diode - Observe polarity

1N4148 1N4148

Diode - Observe polarity

TR1

BC327

Transistor – Observe polarity

TR2

BC212

Transistor – Observe polarity

TR3

BC182

Transistor – Observe polarity

RELAY 12v DPDT

CON3

3.5 Jack Socket or 2 Pin Molex plug

Your choice

SW1

Maybe fitted instead of CON3

Straighten pins of SW1 before fitting

As with the audio amplifier stage, inspect your work before testing.

Содержание FOXX-3

Страница 1: ...transceiver you will need a pair of headphones 12v DC supply a battery is ideal and antenna a tuning unit for the 20m Band A power meter would be useful to A separate Morse key can be used but a board mounted key is provided The FOXX 3 printed circuit board has been designed to give the constructor a number of choices 1 Enclosure a The board can be fitted into an Altoids mint tin All connections a...

Страница 2: ...egative and a positive lead and must be connected the correct way round otherwise they may be damaged when power is applied The negative lead is shorter as supplied and is marked with a minus sign on the body of the capacitor This lead goes through the hole marked with a minus sign and is soldered to the square pad Part Type Markings Notes R1 100Ω Brown Black Brown Gold R2 10KΩ Brown black Orange ...

Страница 3: ...ume and side tone controls fully clockwise Holding the headphones some distance from your ears touch the upper terminal of the volume control with a metal object such as a screwdriver You should hear a buzzing noise in the headphones assuming you are near a mains supply Now touch the upper terminal of the sidetone control and observe a similar buzzing noise Turn the two spindles fully anticlockwis...

Страница 4: ...y is kept energised by the charge on capacitor C13 If the key remains released for more than about half a second the relay contacts change back to the receive position This time can be adjusted by altering the value of R6 The charge on C15 holds the mute transistor on until the relay contacts have changed over Part Type Markings Notes R4 1KΩ Brown Black Red Gold R5 4k7Ω Yellow Violet Red Gold R6 1...

Страница 5: ...ch The relay should give a click as it pulls in energises Release the key and note that there is a short delay before the relay clicks again as it drops out de energises Now connect the headphones to CON2 Touch the upper terminal of the volume control with a metal object as before and turn the volume control clockwise until the buzzing noise is heard Press the Morse key and observe that the buzzin...

Страница 6: ...ed from the keyed 12v line Its output goes to the second input of the LM386 via a separate volume control VR2 Part Type Markings Notes R9 47KΩ Yellow Violet Orange Gold R10 4K7Ω Yellow Violet Red Gold R11 10KΩ Brown Black Orange Gold R12 10KΩ Brown Black Orange Gold R13 10KΩ Brown Black Orange Gold R14 680Ω Blue Slate Brown Gold R15 4M7Ω Yellow Violet Green Gold C18 10nF 103 C19 10nF 103 C20 10nF ...

Страница 7: ...nnect a Morse key to CON3 unless you have fitted the switch to the board headphones to CON2 and a 12v supply to SK1 Press the Morse key or switch Turn the sidetone control clockwise until a musical note can be heard in the headphones Adjust the volume control to a comfortable level using the sidetone control Release the Morse key and notice that the sidetone stops immediately ...

Страница 8: ...essarily over heating the crystal Resistor R17 determines the collector current of the oscillator transistor the amount of drive applied to the PA transistor and so the output power of the transmitter It is marked AOT Adjust On Test on the board The two terminal pins provided should be pushed through the holes for R17 from the track side of the board and their heads soldered to the copper pads R17...

Страница 9: ...r to middle of its tuning range Turn the Rx offset control VR3 fully clockwise Press and hold the Morse key on the FOXX 3 and re tune the receiver until the pitch of the note is comfortable for reading Morse This is usually between 400 and 800 Hz use the FOXX 3 s sidetone pitch as a guide Release the Morse key and turn the Rx offset control anticlockwise noting the rise in pitch of the signal on t...

Страница 10: ...uld be evenly spaced not over lapping with a gap between the first and last turn as shown Wind these in the direction shown so that the wires line up with the holes in the board When the winding is complete trim the wires to a length of around 10mm measured from the edge of the toroid To tin the end of the wires form a bead of molten solder on the tip of the soldering iron and pass the end of the ...

Страница 11: ...upply to CON1 Press the Morse key and measure the output power This should be between 500 milliwatts and 1 watt The power can be altered by changing R17 the resistor soldered to the pins Reducing the value of R17 will increase the power Do not run the FOXX 3 with a power output above 1 watt It may be necessary to readjust the receiver offset as described in the previous stage ...

Страница 13: ... that it cannot discriminate between station above and below its operating frequency If for example the FOXX 3 s oscillator is tuned to 14 060 000 MHz when in receive mode stations on 14 060 800 MHz and 14 059 200 will both produce 800Hz beat notes in the headphones The FOXX 3 can be operated from any DC supply of 9 to 14 volts It draws around 250mA when transmitting so a small 12 volt sealed acid...

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