FX 146
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FX-146 Transceiver Assembly Phase 1: Circuit stages A through E-F
FX-146 MASTER PARTS LIST
Before beginning assembly, take some time to check and organize these kit
components in such a way that you can find them easily and not lose any or
confuse them. Leave parts supplied on tape strips in the strips until you need
them. The following headings also provide logical sorting categories. Popular
methods for organizing parts include egg cartons, muffin tins, corrugated
cardboard edges, or pressing the leads into a block of styrofoam.
INTEGRATED CIRCUITS
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1 MC13135 24-pin DIP FM Receiver IC (U1)
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1 LM380 14-pin DIP Audio Amplifier IC (U2) [Do NOT use socket]
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1 12017 8-pin DIP divide-by 64/65 Prescaler (U3)
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1 LM324 14-pin DIP Quad Op-amp IC (U4)
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1 LM358 8-pin DIP Dual Op-amp IC (U5)
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1 MC145152 28-pin DIP PLL Synthesizer IC (U6)
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4 74HC283 16-pin high speed 4-bit Binary Adder (U7,U8,U9,U10)
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1 7808 8V voltage regulator [VR1]
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1 7805 5V voltage regulator [VR2]
TRANSISTORS:
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5 NPN transistor, type 2N3904 or equivalent (Q4,6,11,15,17)
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3 PNP transistor, 2N3906-type [marked 228256] (Q12,13,14)
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2 NPN VHF type NE02137 (Q3,10) [flat disc type marked '021']
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4 NPN VHF type 2SC2498 or 2570 (Q2,7,5,16)(Sort these carefully
from the 5 type 2N3904 for Q1, etc.)
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1 RF NPN type 2N3866 (transmit driver, Q9)
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1 RF NPN type MRF237 or SD1127 (transmit final, Q8)
DIODES (Note color code descriptions CAREFULLY!):
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1 LED (D17, transmit indicator)
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100+ 1N914 or 1N4148 switching diode
(D1,4,5,8,9,10,11,12,13,14,15,16,19,22,24,26,plus PLL matrix)
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2 Varactor diode, type BB505 (D3, D23) [orange labeled BB505]
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1 PIN diode, type BA479 (D6)
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2 PIN diode, type BA482 (D2, D7) [orange body, red band]
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1 1N4002 rectifier diode (D18) [largest black body, gold band]
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1 6.2 volt zener diode (D20) [gray body with black band]
FX-146
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ADDITIONAL RECEIVER IC FUNCTIONS AND FEATURES
In addition to audio output at pin 17, a separate high speed data output (up
to 35000 baud) is available and may be linked directly to a packet TNC or
other data controller using the jumper wire pad provided on the PC board.
The MC13135 is capable of detecting true FSK (frequency shift keying) in
addition to AFSK.
The receiver has good "hysteresis" characteristics, the ability to hold the
squelch open once it has been broken by a marginal signal, even if the
signal becomes weaker. The IC also has carrier detect circuitry which is put
to good use in the transceiver design by providing very effective squelch
action. The squelch is activated by signal strength, not by noise. When no
carrier is detected, the voltage at pin 16 is high, which causes Q6 to mute
the audio amplifier U2 as explained in Stage B.
When a carrier is detected, the voltage at pin 16 drops low, turning off Q6.
Resistor R13 permits squelch adjustment.
Finally, the carrier detect circuitry affords the same COR ("Carrier Operated
Relay") action as needed in any repeater, which is why the output is also
available on the PC board, designated "COR." It is up to creative users to
determine their own practical implementations for this feature.
Stage CR ASSEMBLY PROCEDURE:
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CR1. Install U1, the MC13135 24-pin DIP FM Receiver IC. Make sure
all 24 pins are visible through the holes before soldering and be very
sure that the notched end is oriented as illustrated.
Install the following resistors:
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CR2. Install R11, 47K ohm (yellow-violet-orange).
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CR3. Install R5, 10K ohm (brown-black-orange).
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CR4. Install R4, 68K ohm (blue-gray-orange).
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CR5. Install R24, 10K ohm (brown-black-orange).
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CR6. Install R119, 270 ohm (red-violet-brown).
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CR7. Take a moment now to double check your work. Touch up any less
than perfect solder connections.
Install the following capacitors:
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CR8. Install C16, .01 uf disc capacitor (marked .01 or 103).
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CR9. Install C5, .01 uf disc capacitor (marked .01 or 103).
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CR10. Install C9, 4.7 or 10 uf electrolytic, observe correct polarity.
