Ramsey Electronics FZ-146 Specifications download pdf (Page 95)

FX-146 • 95

Stage E: 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. Select and install shielded coil L7, stamped 84885-5. It fits in two

different ways, and either way will work. Be VERY sure BEFORE

soldering that this coil is seated snugly on the PC board.

 E2. Install C43, .001 uf (marked .001 or 102).

 E3. Install C54, 56 pf disc capacitor (marked 56).

 E4. Install C51, 22 pf disc capacitor (marked 22).

 E5. Install R30, 51 ohm (green-brown-black).

 E6. Install R22, 10K ohm (brown-black-orange).

 E7. Install R18, 270 ohm (red-violet-brown).

 E8. Install R66, 47K ohm (yellow-violet-orange).

 E9. Install Q7, NPN type 2SC2498. Before soldering be sure to identify

Q7 correctly and to insert it with its flat side as shown in the parts

diagram.

 E10. Install varactor diode D23, type BB505. It has a black body with a

white band. Be certain of correct diode identification and orientation of

cathode (WHITE band) end.

 E11. Similarly, install D3, also type BB505. Watch that polarity!

 E12. Install C36, .01 uf disc capacitor (marked .01 or 103).

 E13a. Install C40, 47 uf electrolytic. Be sure to orient polarity as shown.

 E13b. Install R19, 10K ohm (brown-black-orange).

 E14. Install C39, .001 uf. disc capacitor (marked .001 or 102).

 E15. Install D1, type 1N914 or 1N4148.

 E16. Install R15, upright, 1K ohm (brown-black-red).

 E17. Install C99, .01 uf disc capacitor (marked .01 or 103).

 E18. Install R25, upright, 47K ohm (yellow-violet-orange).

 E19. Install Q4, NPN type 2N3904. Be sure to orient flat side as

illustrated.

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Ramsey Electronics FZ-146 Specifications Page 95