10M Dsb Qrp Transmitter With Vfo Circuit

Description: The three schematics illustrate three building blocks for a 10-meter SSB transmitter. These blocks can also be utilized independently as circuit modules for other transmitters. The VFO board incorporates an FET transmission oscillator, with the VFO signal being mixed in an NE602 mixer and subsequently amplified by Q2 to a level adequate for driving an SBL-1 mixer in the transmit mixer stage (+7 to +10 dBm). In the balanced mixer/modulator board, an 11-MHz crystal oscillator drives a diode-balanced mixer. Additionally, audio for modulation purposes is supplied to this mixer. The DSB signal is then directed to a 28-MHz band-pass filter (BPF). The 1-W amplifier board consists of a three-stage amplifier and transmit/receive switching circuitry.

The 10-meter SSB transmitter schematic consists of three fundamental components, each designed to facilitate specific functions within the transmission process. The first component, the Variable Frequency Oscillator (VFO) board, employs a Field Effect Transistor (FET) as a transmission oscillator. This configuration allows for stable frequency generation, which is crucial for SSB (Single Sideband) transmission. The VFO signal is mixed using an NE602 mixer, a popular choice for its low power consumption and good performance in RF applications. The output from the mixer is then amplified by transistor Q2, ensuring that the signal reaches a sufficient power level of +7 to +10 dBm, which is necessary for driving the subsequent SBL-1 mixer in the transmit mixer stage.

The second component, the balanced mixer/modulator board, utilizes an 11-MHz crystal oscillator. This oscillator provides a precise frequency reference, which is essential for maintaining the integrity of the modulated signal. The diode-balanced mixer effectively combines the incoming audio modulation with the RF signal, allowing for the creation of a Double Sideband (DSB) signal. This DSB signal is then routed to a 28-MHz band-pass filter, which serves to eliminate unwanted frequency components and ensure that only the desired signal is transmitted.

The final component is the 1-W amplifier board, which is designed to amplify the processed signal for transmission. This board features a three-stage amplifier configuration, which enhances the signal strength while maintaining linearity to prevent distortion. Additionally, the board includes transmit/receive switching circuitry, allowing for seamless transitions between transmitting and receiving modes. This comprehensive design ensures that the 10-meter SSB transmitter operates efficiently and effectively, with each block contributing to the overall functionality of the system. The three schematics represent three building blocks for a 10-meter SSB transmitter. Or these blocks can be used separately as circuit modules for other transmitters. The VFO board uses an FET transmittal oscillator, the VFO signal is mixed in an NE602 mixer and is amplified by Q2 to a level sufficient to drive an SBL-1 mixer in the transmit mixer stage (+7 to +10 dBm). In the balance mixer/modulator board, an 11-MHz crystal oscillator drives a diode balanced mixer. Audio for modulation purposes is also fed to this mixer. The DSB signal feeds a 28-MHz BPF. The 1-W amplifier board consists of a 3-stage amplifier and transmit/receive switching circuitry.