Ramsey Electronics FM25A Assembly And Instruction Manual - page 13
FM25A
• 13
Power Supply
1b. Install C5, the large 470 - 1000 µF electrolytic capacitor. Be sure to po-
sition for correct polarity.
2b. Install VR3, the 7812 12 volt regulator. Make sure the metal tab is ori-
ented as shown in the parts layout. The text side of the component should
be facing S1.
3b. Install VR1, the 78L05 5 volt regulator. Make sure the flat side of the
component is facing the same direction as shown.
4b. Install C7, a .01µF ceramic capacitor (marked .01, 103, or 10n).
5b. Install C3, a 10µF electrolytic capacitor. Pay attention to polarity!
6b. Install C4, a 100µF electrolytic capacitor. Watch polarity.
We’ll save the other power supply components for later in favor of ease of as-
sembly.
Transmitter
1c. Install R6, the small yellow trimmer potentiometer marked "104".
2c. Install R21, 4.7K (yellow-violet-red).
3c. Install R22, 150K (brown-green-yellow).
4c. Install C33, 220 pF disc capacitor (marked 220 or 221 or 220K).
5c. Install C34, 10µF electrolytic capacitor. Observe polarity.
6c. Install C28, .001 µF disc capacitor (marked .001 or 102).
7c. Install C12, a .001 µF disc capacitor (marked .001 or 102).
8c. Install C18, 5 pF disc capacitor (marked 5 or 5K).
9c. Install C20, 5 pF disc capacitor (marked 5 or 5K).
10c. Install C15, .01 µF disc capacitor (marked .01 or 103 or 10 nF).
11c. Install R7, 100K ohms (brown-black-yellow).
12c. Install D21, it looks like a transistor with only two leads (marked
MV2105). Notice the placement of the flat side, it should face L1.
13c. Install R10, 470 ohms (yellow-violet-brown). The outside lead on this
resistor is TP1, Test Point 1. You will be measuring voltage at this point.
14c. Install C19, 10 µF electrolytic capacitor. Observe polarity.
15c. Install shielded slug tuned coil L1. The larger tabs secure the shield
can to the ground foil connections, while the two thin leads are the coil con-
nections. If you find that the coil lead wires do not line up with the PC board
holes, simply "pull" the coil insert from the shield can, rotate it a quarter-turn