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470khz tube amplifier

Heterodyne and homodyne receiver architectures are used to convert modulated RF signal to IF signal. Superheterodyne uses RF vs IF. AF amplifier is used for audio frequencies, i. RF amplifier is used for radio frequencies, i. RF and microwave signal generators.


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WATCH RELATED VIDEO: 300B DIY Budget Tube Amplifier Build DHT SET

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This page gives a brief explanation of what valves are, how they work, and how they are or were used. The first television set I ever saw appeared in our house in about It looked like this - except it was in a box, obviously.

My dad had built it from a kit. They made their own entertainment in those days. The programmes were rubbish, the picture was a grainy black and white on a 9" tube, and yet my brother and I were entranced. It was the most amazing thing we had ever seen. Moving pictures! Right there in our living room! Manufactured in large numbers during the war, valves were suddenly cheap and widely available. TV receivers became affordable for the first time. Some pedants refer to valves as 'thermionic' valves, to distinguish them from the valves plumbers fit, whilst Americans know them as 'vacuum tubes'.

They look like oddly shaped light bulbs, or fat metal tubes. There are six of them visible in the picture. Think of a plumber's water valve, or a tap. It's basically a pipe with an adjustable vane inside it. The vane can be rotated from outside the pipe between fully closed and fully open. You can control precisely how much water flows through the valve by adjusting the angle of the vane. A valve like those in the TV set works by controlling the flow of electric current.

The key point is that both types of valve allow an external force to influence what's happening inside. That's enough about water. From now on, valve means the kind you would find in an old television like the View Master. These valves control electric current. A current is a stream of electrons, all flowing in the same direction.

So a valve needs a source of electrons, a target for them to aim at, and a force to move them. Plus, of course, a means of controlling how many electrons are moving. The simplest possible way to achieve this is by means of a structure consisting of just three components.

The structure is known as a triode. Engineers needed a way of thinking about a valve without worrying about unnecessary details such as its physical size or the actual shape of its components. They came up with a descriptive symbol. I found this version in the March edition of Modern Wireless , and it's still recognisably a triode. At the bottom of the diagram is the filament. Its job is to emit electrons. At the top is the anode or plate, as Americans say.

It is connected to a large positive voltage, so the electrons swarm towards it. Between the filament and the anode is the grid. It is not solid - the electrons can pass right though it. But when a negative voltage is applied to the grid that is, when the grid is made more negative than the filament some electrons become discouraged on their journey, and turn back.

A sufficiently large negative voltage stops all the electrons from passing whilst a zero voltage allows them all to pass unhindered. Allowing the grid to become more positive than the cathode is generally considered a bad thing to do. It's essential that the electrons can move freely, so the whole structure operates in a vacuum, held usually inside a glass bottle. The base carries pins which plug into a valve-holder, allowing the valve to be replaced when it fails.

And it will fail, just as a lightbulb will fail. Valves are not reliable components. A valve is an amplifier. Its output signal is much bigger than its input signal. So in principle a simple radio receiver could be made from a single valve with an aerial connected to its input and a set of headphones at its output. Modern Wireless July shows how.

The tuned circuit L 1 , C 1 selects the frequency. L 2 provides positive feedback - they called it "reaction" then - which increases gain and selectivity right up to the point when the circuit begins to oscillate and becomes a transmitter. In the accompanying list of Materials and Components Required, it says simply "1 valve". There is no further clue as to what type of valve is needed here, so I assume there was only one type of valve available. The world had not yet realised what a fantastic transformation these and their successor devices transistors and integrated circuits would bring within a couple of generations.

In the s, valves existed mainly so that serious experimenters could build radio receivers. Thirty years later the serious experimenter could build his own television set. The circuit below is the video receiver for the View Master TV shown at the top of the page.

Triodes have one grid, but these newer amplifier valves possess three and are therefore called pentodes. The additional grids are known as the 'screen' and the 'suppressor', and including them greatly improves the valve's performance. I'll explain why, later. Another obvious difference is that the filament is no longer the source of the electron stream.

Instead, the filament now heats an electrode known as the 'cathode', which is specifically designed to emit copious quantities of electrons in a smooth stream. A huge number of these were manufactured during the war for use in radar receivers.

The best way to find out is to have a look. I put an ECC83 dual triode in a vice and gently crunched the glass envelope until it fell away, then after removing various layers of mica I was left with the important bits. The left-hand photograph clearly shows the structure: a small tube the cathode surrounded by a spiral of wire the grid inside a large rectangular metal box the anode. The tiny heating filaments can be seen in the picture on the right, which also shows how the structure is supported and connected to the outside world.

Valve manufacturers helpfully publish the characteristic curves of their products. These graphs are produced by putting a fixed voltage between the grid and cathode of a triode, and gradually increasing the anode voltage whilst measuring the anode current. When the grid voltage is zero, the graph is almost a straight line, reaching 5mA anode current at about v.

Making the grid more negative reduces the anode current, as you would expect, and anode current falls to zero when the grid voltage reaches around -5v.

So a relatively small variation in grid voltage can produce quite a large variation in anode current. This means the valve can amplify signals.

Here, the red line indicates how the anode current and voltage will move as the grid swings up and down by 0. A valve needs a large positive supply voltage. The valve amplifies by using the varying grid voltage to cause a varying anode current. But the amplifier output needs to be a varying voltage , perhaps to feed the next amplifier, so a resistor is required to convert the current into a voltage.

How big should it be? The relationship between anode current and voltage is fixed by the 51k load. If, for example, anode current happened to be 2mA, then the anode voltage would have to be v. What should the anode current be when there is no input signal? The designer must decide. In this example, I chose 1. This coordinate 1. I could have fixed it almost anywhere in the graph provided the grid voltage was negative, of course.

Now, suppose the input signal is a 1v peak-to-peak sinewave. It will cause the grid voltage to swing up and down by 0. The 1v p-p input signal yields a 50v p-p output signal. This amplifier has a gain of The grid must be kept more negative than the cathode. But this just means that the cathode must be kept more positive than the grid , and it's easy to achieve this by adding a resistor S between the cathode and ground.

Anode current which is the same as cathode current flows through S, so the cathode must be more positive than ground. Provided the grid is connected to ground, the grid must be more negative than the cathode. However, the cathode resistor S introduces negative feedback into the circuit, which would reduce the gain. To avoid this, it's common to add a capacitor C in parallel with S. C is chosen to have an impedance that is much lower than S at the frequencies the amplifier is designed to handle.

In the example above, I wanted It is said that beam tetrodes such as the KT66 and the were only developed because a well-known manufacturer held a patent on the suppressor grid. Thanks to our daughter-in-law Ewa Hearfield her other work is here and here of Ewapix for this clear photograph of the A triode doesn't work well at high frequencies because the signal leaks back through its anode-grid capacitance.


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It works very much in the same way as my Transistor Pulse Counting FM Receiver but uses valves and the unusual thing about this design it will work on low voltages even as low as 15 volt if the local oscillator anode decoupling resistor is optimized to a lower value to suit. Low voltage operation of valve radio circuits is not really anything new and circuits for 1or 2 valve regenerative short wave receivers have appeared in radio magazines of that era. Also car radios of the late 50s used this method using special space charge valves designed for 12 Volt operation for the radio section and the usual AD and AD germanium power transistors used for the power output stage to drive a loudspeaker. It was still necessary in some cases to use valves particularly if it was a portable FM set as transistors suitable for VHF work had not quite caught up in technology until the early s. Although RF and IF amplification is possible using normal mains valves at these low voltages, the power output is very limited because the emission of the cathode current is only about 1 to 3 milliamps at these voltages. If you are in a quite listening environment such as a bedroom or small office you can get usable results of about not more then 3 miliwatts of audio power from a small EL84 power valve or an even more economical valve such as the ECC86 designed for low voltage operation. The ECC86 has a cathode current of 10 milliamps per triode and will give a loudspeaker output of about milliwatts from the main 25 Volt HT line at very pleasing volume and good audio reproduction.

ex 20 00 | 20 | Glass cone (funnel) for cathode-ray tube with a on which are mounted a deflection unit, a video-amplifier and a transformer.

Superheterodyne Receiver - History


In this state was the neglected old tube radio for sale at a flea market for 10 euros. And this is how the neglected radio has been refreshed! You can repair a tube radio with a screwdriver-voltage finder, no expensive voltmeter needed! He was really dirty and badly neglected. The tubes. Antonio De Vega also has such a radio and made this diagram! Part 2 of Antonio's diagram. The tubes even had original labels! First take it apart and clean it completely with brushes, tweezers, soapy water and so on.

DECEMBER 1975 GUITAR AMPLIFIER CHRISTMAS LIGHTS FLASHER

470khz tube amplifier

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In communications and electronic engineering , an intermediate frequency IF is a frequency to which a carrier wave is shifted as an intermediate step in transmission or reception.

What is difference between RF and IF?


Specification , Electrosurgical , Ellman surgitron ffpf electrosurgical , Ellman , Surgitron , Ffpf , Ellman surgitron ffpf electrosurgical specifications. Link to this page:. REMstar Pro 2 with C- Flex , if it is making unusual or harsh sounds, if it has been dropped or mishandled, if the enclosure is broken, or if water has entered the enclosure, disconnect the power cord and discontinue use. Contact your home care provider. Flex , Smarter.

Ift3 470khz Am Intermediate Frequency Transformer From 1962 Hacker Herald

User Name Stay logged in? If you design your current feedback amp with Discrete Frontend instead of using opamp. Kanwar, I have analyzed many CF designs with Descrete Frontend However, if you consider the techical data you will find that the Op-amp front-end designs give lower distortion figures, widest power bandwidth Take an example, The Compact Power Amp from T. Giesberts published in Elektor magazine in uses descrete front-end. It's Power bandwidth is Khz whereas the two designs with op-amp I saw give around 1Mhz. Nevertheless Mr Mark Alexander gave the formula to calculate powerbandwidth.

which combines the advantages of a fixed-frequency amplifier with variable kHz and kHz is generally chosen, since these frequencies represent a.

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This discussion will be based solely on super-heterodyne superhet circuits. For information on this type of circuit click here. The carrier is a fixed frequency the frequency you tune the set to , and the amplitude voltage level of this is varied by the audio signal being transmitted. LW currently unused kHz Metres.

In communications and electronic engineering , an intermediate frequency IF is a frequency to which a carrier wave is shifted as an intermediate step in transmission or reception.

The Stellar M from PS Audio is a mono amplifier with a valve input stage, tremendous power, a gorgeous design and a sound quality to match its Stellar title. One of the only reasons to not consider this unit is if you simply don't need this much power. Click here for more information about Australian Hi-Fi , including links to buy individual digital editions and details on how to subscribe. After carefully noting the printed warning on the rear panel about not connecting the negative terminals to ground more on this later in the review , I switched on the amplifier I was using to drive the left channel speaker only to have the front panel logo light up, then almost immediately extinguish. Mild panic. Had I accidentally shorted an output? So I checked the wiring again.

The new Aeromotive A Fuel Pump is an upgrade and redesign to The uBer switch is a small microcontroller controlled true-bypass with relay. Started building pedals this month Sibob, is the pedal true-bypass? At it's heart is a tweaked RAT surrounded by 2 opamp gain stages and buffered bypass, all running on 18 volts schematic below.




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