Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
Tags: none
Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
Tags: none
Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Key words: PHASE-LOCKED. As the name implies, a PLL synthesizer includes a voltage-controlled oscillator (VCO) whose output is constantly compared to a stable crystal reference. If the phase of the output signal begins to lead or lag the reference (a phase error), a correction is applied to the oscillator tuning. If the reference is noisy or subject to phase jitter, the output is similarly corrupted.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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In an oscillator, stability is paramount. Silver Mica, NP0 (N-P-Zero, negative-positive-zero) ceramic and polystyrene capacitors are temperature-stable. The electrolytic is suitable as a filter or audio bypass. The plain ceramic capacitor is good for coupling or RF bypass.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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An oscillator, fixed or variable, is an amplifier with a positive feedback path from output to input used to start and maintain oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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A simple two-stage CW transmitter comprises an oscillator and a Class-C power amplifier. A transformer at the output of the oscillator serves the dual purpose of tuned circuit and coupling to the next stage. The DC supply to the final amplifier is bypassed to ground with a capacitor and decoupled through an RF choke so RF is kept out of the supply.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
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Hartley = a tap on the inductor of the tuned circuit permits inserting positive feedback from output to input. Colpitts = the inductor tap of the Hartley is replaced by two series capacitors in a capacitive divider configuration. Relatively large capacitor values, when compared to the Hartley, mean less influence from internal capacitance changes in the device, hence stability. Pierce = derived from the Colpitts, a piezoelectric crystal replaces the tuned circuit. Capacitive coupling maintains oscillation.
Original copyright; explanations transcribed with permission from Francois VE2AAY, author of the ExHAMiner exam simulator. Do not copy without his permission.
Tags: none