Ramsey Electronics FX-440 Manual page 97

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BASIC VCO ASSEMBLY
In this Stage, we will assemble the basic VCO (Voltage Controlled
- Oscillator) circuit. Understanding the function of this stage is especially
important for knowing how the FX transceiver works.
[ ) [ ) E1. The VCO inductor, L7 is a PC board trace. It is tuned by
moving a wire "short" along its length. Select a scrap component
lead wire and bend it into a right-angle. Cut one end of the wire
114" long.
114" LONG
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LONG LEG GOES IN HOLE
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PLACE SHORTING WIRE HERE.
[ ) [ ) E2. Insert the long wire into the hole along side L7 BETWEEN
the two lines printed on the PC board. Push the wire flush against
the PC board, you should now have the short end neatly sitting on
the L7 trace between the printed lines. Solder both ends of the
wire. Do not use too much solder on the top of L7 as we will
s;l9htly adjust it during test.
[ ) lkf'E3,,. Install C43, .001 uf (marked .001 or 1000 or 102).
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Install C51, 8.2 pf.
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(¥f'E5. Install C54, 8.2 pf.
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E6. Install R30, 51 ohms (green-brown-black).
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Install R22, 22K (red-red-orange).
[ ] [0'8. Install 07, NPN type NE021. Use the same technique for
installing 07 as you did for the other NE021 devices.
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tJ-·E9. Install R18, 2 ohms (red-black-gold).
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E10. Install varactor diode 023, type BB405. It has a black body
with white and green bands. Be certain of correct diode
iqentification and orientation of cathode (WHITE band) end.
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E11. Similarly, install 03, also type BB405.
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Et2. Install C36, .01 uf.
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Install C40, 47 uf, electrolytic. Watch polarity.
[ ) a:(E13b. Install R19, 1 K (brown-black-red).
- FX-440 /iv
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Assm. 37