The Kenwood TM-733A is an older dual-band mobile radio. This radio is capable of 50 watts transmit on VHF, 35 watts on UHF, full-duplex crossband repeat, and simultaneous receive on two VHF or UHF frequencies. It does have a problem, however: It is terribly sensitive to being overloaded by other signals. The effects of overload (or `intermod` - co
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mmonly referred to as IMD meaning "InterModulation Distortion") manifests itself as the reception of signals that aren`t really on frequency. During a `bout of intermod, one will often hear QSOs of other repeaters (amateur and not) as well as odd bleeps and buzzes from paging and telemetry systems. Because intermod is a mix of multiple signals, you cannot experience it from just one signal - it takes at least two signals! Even before I got my own `733, I was aware of the problem: Back in early 90`s a friend of mine bought a TM-732 - the predecessor to the TM-733. It had some pretty nice features and a reasonably intelligent (I thought) operator interface. But it had terrible intermod problems: It would seem to squeal and squawk at almost any time, anywhere due to front-end overload. He asked me to look into it and see if there was something that I could do about it. For an FM receiver, the stronger the signal, the less noisy it is. When quantifying sensitivity measurements, a common standard is to have a signal with a 1 KHz tone at a deviation of 3 KHz. The "SINAD" is the ratio of that 1 KHz tone to the background noise. The "12 dB SINAD" measurement is how much signal is required to get that tone 12dB above the "popcorn" noise one hears on a weak FM signal. How noisy is a signal with 12dB of SINAD Pretty noisy - but if the other person is talking in a normal voice (i. e. not quietly or far from the microphone) 12dB of...
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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