Electronics - Lessons

Operation in the CW RF generator mode and measurement of parameters of radio components using NanoVNA. The NanoVNA can function as a stable, fixed-frequency Radio Frequency (RF) signal generator ( CW Mode or Zero Span ). The generator's signal is output exclusively from port CH0 . Activating the Generator via the Menu Open the main menu by tapping the screen. Navigate to the STIMULUS section. Tap the CW FREQ button. Using the virtual keypad, enter the desired frequency and select the multiplier (e.g., M for MHz). The device will immediately switch to emitting a continuous carrier wave at the specified frequency, and the frequency sweep will stop. Generator Output Signal Characteristics Nominal output power: Approximately -13 dBm into a 50-ohm load. Waveform: Since the generator is based on the Si5351 synthesizer chip, ...

Cable Parameter Measurement and Time-Domain Reflectometry (TDR) With the NanoVNA, you can easily locate discontinuities in coaxial cables, measure the exact length of a feeder line, and find transmission line faults (such as open or short circuits) without the need to unroute or remove the cable. Time-Domain Reflectometry (TDR) This function is based on the Inverse Fast Fourier Transform (IFFT), which converts the measured vector parameters in the frequency domain into a time-domain line response. A signal pulse is sent into the cable, reflects off a discontinuity (the end of the cable, an open circuit, or a short circuit), and returns. The device calculates the exact distance based on the time delay of the reflected signal. Schematic representation of impulse probing of a cable line (TDR). Steps for setting up TDR on the NanoVNA screen: Perform an OSL calibratio...

Audio Frequency (AF) Amplifiers Actually, there is an overwhelming number of such circuits on the Internet. They vary in class, implementation, and parameters—ranging from simple designs to complex AF amplifiers with multi-loop negative feedback to minimize distortion. Building a "Hi-Fi" class AF amplifier for a ham radio receiver makes no sense for one simple reason: the signal source (the received airwaves) is far from a "musical" audio spectrum. On the contrary, it is a noisy, "dirty" audio spectrum because it reproduces "live" on-air signals. Received stations can experience fading and associated distortions, as well as high signal levels that cause noticeable clipping. Therefore, amplifying such signals with a "Hi-Fi" class amplifier is absurd, to say the least! All circuits in this section are my own designs, based on knowledge and information gathered from public Internet sources. ...