Any mode (e. g. CW, AM, SSB, FSK) which is initiated in the HF transmitter or transceiver can be regenerated at LF (100 to 200 kHz) using this simple converter. The output at LF can be used to drive an LF Power Amplifier. The February, 2000 issue of Amateur Radio (ref. 1) contained an article I had submitted on an LF transmitter. The transmitter wa
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s designed for CW operation but the power amplifier was operated in a linear mode and it was only a matter of replacing the VFO with some form of AM or sideband generator with an LF output to operate on speech. The article was followed up with a further article (Amateur Radio September 2000, ref 2) on a Single Sideband Generator using the phasing technique. The design aimed at making a stand-alone unit because of the possibility of using the unit at a site away from the amateur station. However it was pointed out that a simpler arrangement might be achieved at the amateur station site by heterodyning down from the HF output of the local HF transceiver. This third article describes a circuit designed to do that conversion and provide sufficient LF output level to drive the original power amplifier. The circuit diagram of the converter is shown in figure 1. The conversion takes place in V1 (type NE602). The V1 circuit is almost identical to that used in my Active Loop Converter (Amateur Radio July, 2000 - ref 3) except that the input and output frequencies are reversed. I used the same 4 MHz xtal as in the receive converter as I had another one spare. Most HF amateur transceivers tune up to 4 MHz on the 3. 5 MHz band so that it is simply a matter of setting the transceiver frequency to 4 MHz minus the LF transmission frequency. (4 MHz plus LF transmission frequency could also be used if the transceiver is tuneable above the 4...
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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