A classic amateur radio transmitter topology, the oscillator-amplifier (sometimes called master oscillator, power amplifier, or MOPA), used one tube for frequency control and another for RF power amplification, and in quartz-crystal-controlled form commonly allowed operation on two or more bands with one crystal. Frequency multiplication ”generat
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ion and selection of harmonics (multiples) of the crystal oscillator`s fundamental frequency ”was the basis for this. In the earlier days of frequency multiplication, separate stages performed the roles of frequency generator and harmonic multiplier because only triode vacuum tubes were available. The advent of the screen-grid tube (tetrodes, pentodes, and beyond), the embedded screen grid/control grid/cathode triode in which could serve as a triode oscillator at the crystal fundamental while harmonic output was obtained by suitably tuning the plate, made two-tube, three- and four-band oscillator-amplifier transmitters possible by 1933 CE. Nearly all screen-grid oscillators capable of this class of operation are a form of tri-tet, although non-tri-tet variations, such as Frank Jones`s harmonic Pierce oscillator, were possible as well. Seeking to approach the utility of the tri-tet multiband oscillator with transistors, and having achieved excellent results in synthesizing a tetrode with cascode-connected vacuum-tube triodes for regenerative-detector service, I recalled the cascoded-BJTs VCO buffer amplifier described by David Stockton, GM4ZNX, in the Oscillators and Frequency Synthesizers chapter he wrote for the 1995 CE ARRL Handbook for Radio Amateurs and wondered if an oscillator based on cascoded transistors might approach the multiband utility of the tri-tet. Through private correspondence, Wes Hayward, W7ZOI, pointed...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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