One of the best RF amplifiers ever published was Wes Hayward`s post mixer amplifier in the Progressive Communications Receiver. It quickly became known as a great high level RF amplifier. With a standing current of 50ma, it takes a very strong signal to upset this amplifier. Check out page 15. 24, figure 15. 33 of the 2000 ARRL Handbook for Radio Amateurs for more information.
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This receiver is designed to work in the worst conditions that many hams have to tolerate: living in a condo or townhouse with antenna restrictions. A Hamstick antenna mounted just inside a bedroom window (in a townhouse) was used to test the sensitivity of the receiver. A 16-18dB RF amplifier was used to provide the necessary sensitivity to work with a hamstick in a townhouse/condo. When this receiver is used with better antennas, the front end gain needs to be "tuned" for the antenna system used. The RF amplifier needs to be bypassed in really good antenna systems, and maybe used only on the 17 meter band. Instructions for bypassing the RF amplifier are near the bottom of this page. The right amount of gain is a compromise between sensitivity and dynamic range. When using a Hamstick, signal levels are so low that going all the way for sensitivity gives a very good performing setup. An excellent article that shows the effectiveness of using Hamsticks in a dipole configuration is "Receiving Antennas", by Robert L. Nelson, K6ZGQ, Ham Radio, May 1970, pp 56-63 (Subtitled: "A discussion of special purpose antennas for receiving - including some novel ideas for improved performance on the lower bands"). Mr. Nelson states, from the article above (page 62), "I have obtained good results with both a helical dipole and an untuned five-foot-long dipole with a capacitive hat when worked through an antenna coupler. However, the...
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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