Two Stage Fm Transmitter
gKit 32. TWO STAGE FM TRANSMITTER
This Kit is a powerful two stage, 9V FM transmitter (Tx) with a range of up to 1 kilometer in the open. It uses an RF transistor in its output stage. Distance of transmission is critically dependent on the operating Conditions (in a building or out on the open), type of aerial used (single wire or dipole), operating voltage (12V is better than 6V) and if the circuit is peaked for maximum performance. The kit is constructed on a single-sided printed circuit board (PCB). It has a silk screen overlay on top to aid construction. On the bottom there is a solder mask to help in soldering. Protel Autotrax and Schematic were used to design the board. ASSEMBLY INSTRUCTIONS Components may be added to the PCB in any order. It is usually easier to add the lowest height components first then proceed to the taller components. The electret microphone should be inserted with the pin connected to the metal case connected to the negative rail (that is, to the ground or zero voltage side of the circuit.) This is marked with a '-' sign at the MIC on the circuit board printed overlay. To save space all the resistors must be inserted standing up on one end. Be careful to get the transistors around the correct way. Note three points: - the two 100n capacitors on the PCB have 0.2" and 0.1" spacing. We have put in components with the correct spacing for ease of construction. - we have supplied prewound, pre-soldered enamel 6 turn & 8 turn wire coils. The legs should solder directly to the pads of the PCB. However, pay special attention to the solder joint in case all the enamel has not been removed. You may have to solder off or scrape off more enamel from the ends of the two enamelled coils. - a connection (or tap) is required from the middle of the L1 tinned copper wire coil to the pad marked TAP next to the coil. Solder a piece of wire to the top of the middle turn as shown on the overlay. Then solder the other end to the pad immediately next to the L1
This Kit is a powerful two stage, 9V FM transmitter (Tx) with a range of up to 1 kilometer in the open. It uses an RF transistor in its output stage. Distance of transmission is critically dependent on the operating Conditions (in a building or out on the open), type of aerial used (single wire or dipole), operating voltage (12V is better than 6V) and if the circuit is peaked for maximum performance. The kit is constructed on a single-sided printed circuit board (PCB). It has a silk screen overlay on top to aid construction. On the bottom there is a solder mask to help in soldering. Protel Autotrax and Schematic were used to design the board. ASSEMBLY INSTRUCTIONS Components may be added to the PCB in any order. It is usually easier to add the lowest height components first then proceed to the taller components. The electret microphone should be inserted with the pin connected to the metal case connected to the negative rail (that is, to the ground or zero voltage side of the circuit.) This is marked with a '-' sign at the MIC on the circuit board printed overlay. To save space all the resistors must be inserted standing up on one end. Be careful to get the transistors around the correct way. Note three points: - the two 100n capacitors on the PCB have 0.2" and 0.1" spacing. We have put in components with the correct spacing for ease of construction. - we have supplied prewound, pre-soldered enamel 6 turn & 8 turn wire coils. The legs should solder directly to the pads of the PCB. However, pay special attention to the solder joint in case all the enamel has not been removed. You may have to solder off or scrape off more enamel from the ends of the two enamelled coils. - a connection (or tap) is required from the middle of the L1 tinned copper wire coil to the pad marked TAP next to the coil. Solder a piece of wire to the top of the middle turn as shown on the overlay. Then solder the other end to the pad immediately next to the L1