Ramsey Electronics FM25A Instruction Manual download pdf (Page 15)

FM25A • 15

 8d. Install Q2, the other transistor marked C2498 (or 2570). Again watch

the placement of the flat side and mount as flush as possible.

 9d. Install R18, 10K ohms (brown-black-orange).

 10d. Install R14, 220 ohms (red-red-brown).

 11d. Install C23, .01 µF (marked .01 or 103 or 10 nF).

RF Lowpass Filter

 1e. Install C35, a 47pF ceramic capacitor (marked 47 or 47K).

 2e. Install C27, a .001µF ceramic capacitor (marked .001, or 102). This is a

coupling capacitor for preventing DC from being present on the antenna or

J4, the external antenna jack.

 3e. Install L2, one of the small pre-wound spring style inductors.

 4e. Install L3, the other small pre-wound spring style inductor.

 5e. Install C36, a 75pF ceramic capacitor (marked 75 or 75K).

 6e. Install C37, a 47pF ceramic capacitor (marked 47 or 47K).

Synthesizer

 1f. Install C26, .001 µF disc capacitor (marked .001 or 102 or 1 nF).

 2f. Install R12, 100 ohms (brown-black-brown). Note this part is a laydown.

 3f. Install R23, 10K ohms (brown-black-orange).

 4f. Install R24, 10K ohms (brown-black-orange).

 5f. Install R25, 10K ohms (brown-black-orange).

 6f. Install R26, 10K ohms (brown-black-orange).

 7f. Install D9 - D20, small glass diodes. The banded ends go toward the

inside of the board, as shown on the silkscreen.

 8f. Install S3, a four posistion DIP switch. The DIP switches are used for

programming the exact transmitting frequency of your transmitter.

 9f. Install S4 and S5 in the same manner.

 10f. Install Y1, the 6.00 MHz crystal (marked 6.00)

 11f. Install R3, 10M ohm (brown-black-blue).

 12f. Install C1, 27 pF disc capacitor (marked 27 or 27K).

 13f. Install C2, 27 pF disc capacitor (marked 27 or 27K).

 14f. Install C9, .1 µF disc capacitor (marked 104 or .1 or 100 nF).

 15f. Install R5, 10K ohms (brown-black-orange).

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Ramsey Electronics FM25A Instruction Manual Page 15