Simple Transmitter
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4 Band Double Tuned Preselector
The circuit requires an RF input, which can be sourced from either a long wire or a loop antenna. The preamplifier operates within a frequency range from 550 kHz (Medium Wave) up to 30 MHz in the shortwave band. The...
RF field strength meter
A simple Field Strength Meter consists of a small antenna, a detector diode, a resistor, a capacitor, and a micro ammeter. This circuit is sensitive enough to detect HF fields when positioned close to the transmitting antenna. The circuit functioned...
Wireless am microphone
The transistor Q1 and its associated components form a tunable RF oscillator. The RF signal is directed to transistor Q2, which functions as the modulator. Operational amplifier IC1 amplifies the audio signal and transmits it through resistor R4 to the...
1929 MOPA 80 meter transmitter using a pair of 27 triodes to an 865 tetrode
This transmitter originated as a conventional shunt-fed Hartley oscillator for 80 meters, utilizing a pair of 27 triodes connected in parallel. With 300 VDC applied to the plates of the 27s, it produced approximately 4 watts of output with decent...
Interfaces For The Remote-Control Transmitter Circuit
Several possible interface circuits are presented for use with a remote-control transmitter. The circuit labeled A demonstrates a typical FM stereo MUX decoder with a load connected directly to the open-collector output of a TA7343 PLL. The circuit labeled B...
GBPPR 1 GHz RF Spectrum Analyzer
An RF spectrum analyzer is an essential tool for experimenters. The spectrum analyzer project described here is an enhancement of the "Spectrum Analyzer for the Radio Amateur" (Part 2) project by Wes Hayward (W7ZOI) and Terry White (K7TAU), which appeared...
WIRELESS MICROPHONE
An operational amplifier integrated circuit (741) amplifies the audio signal from microphone 1 (MIC1), with resistor R12 determining its gain. The amplified audio signal is then directed to the oscillator circuit, which includes transistor Q1 and associated components. D2 functions...
RF Remote Control Encoder and Decoder Chips Explained
Creating a universal remote control system has become quite straightforward. One can acquire the necessary chips, assemble them, and the high-tech remote control device will be operational. This document discusses specific remote control chips designed for this purpose. The IC...
1W-cwtransmitter
This is a small transmitter designed to fit inside a plastic Easter egg. It delivers approximately 1 W of measured RF output into a 50-ohm dummy load and does not generate any heating issues within the circuit. The crystal used...