What is vacuum tube emission?
A vacuum tube, also called a valve in British English, is an electronic device used in many older model radios, television sets, and amplifiers to control electric current flow. The cathode is heated, as in a light bulb, so it will emit electrons. This is called thermionic emission.
What are the negative factors with vacuum tubes?
Vacuum Tubes: Disadvantages
Bulky, hence less suitable for portable products. Higher operating voltages generally required. High power consumption; needs heater supply that generates waste heat and yields lower efficiency, notably for small-signal circuits. Glass tubes are fragile, compared to metal transistors.
Are old vacuum tubes worth anything?
Some older Western Electric tubes unused or the original box will sometimes sell for over a thousand dollars at auction. Western Electric “Tennis Ball” tubes have glass globes about the size and shape of a tennis ball with a glass tip on the top. These numbers include 101D ($400+) and 205D ($300+).
Are vacuum tubes still being used today?
1990s-Today – Vacuum tubes are still used today. Musicians still use tube amplifiers and claim they produce a different and desirable sound compared to solid state amplifiers.
Why are vacuum tubes used?
By using vacuum tubes instead of mechanical relays, computers could move away from mechanical switching and speed up switching on and off the flow of electrons. Vacuum tubes were also used in radios, televisions, radar equipment, and telephone systems during the first half of the 1900s.
How do vacuum tubes work?
All modern vacuum tubes are based on the concept of the Audion–a heated “cathode” boils off electrons into a vacuum; they pass through a grid (or many grids), which control the electron current; the electrons then strike the anode (plate) and are absorbed.
Why did we stop using vacuum tubes?
Vacuum tubes suffered a slow death during the 1950s and ’60s thanks to the invention of the transistor—specifically, the ability to mass-produce transistors by chemically engraving, or etching, pieces of silicon. Transistors were smaller, cheaper, and longer lasting.
Why are vacuum tubes not Made in USA?
I would have had to design new production line equipment and have it all built, which is very expensive. There wasn’t enough of a demand and profit margin to justify that investment.
How long does vacuum tube last?
Power tubes like EL34’s and KT88’s are good for about 2500 hours or more. But may go longer in an amplifier with a conservative design. Small signal tubes with numbers like 12AX7, 12AU7, and 6922, and rectifier tubes like 5AR4 may go 10,000 hours. So you get years and years of enjoyment.
Why are old radios worth money?
Older radios tend to fetch somewhat more than newer ones, but only in a very general way. Age alone doesn’t make a radio priceless. 1920s radios are old, but some manufacturers made cheap, junky radios in those days, as in all other times. Scarcity of parts can make certain vintage sets very expensive to repair.
Are Chinese vacuum tubes any good?
Modern Chinese Vacuum Tube Amps can be very good but are restricted by the cheap mass market valves that are produced purely for consistency and cost restraints. Chinese Tubes such as 6J1, for instance are a direct copy and hence a direct equivalent of Russian 6J1P etc, etc.
How many types of vacuum tubes are there?
There are a lot of different vacuum tube types, all with their own applications, characteristics and construction, most of which fall into four general types: (1) The diode, (2) the triode, (3) the tetrode, and (4) the pentode.
Why do vacuum tubes glow blue?
Sometimes you may notice a blue hazy glow inside your amp tube. This glow is rarely a sign of a defect and is fairly common especially in modern power tubes. This type of glow is called Fluorescence. This phenomenon is due to electron bombardment of the glass taking place within the tube.
Do vacuum tubes emit light?
Their distinctive orange, red, or purple glow during operation indicates the presence of gas; electrons flowing in a vacuum do not produce light within that region. These types may still be referred to as “electron tubes” as they do perform electronic functions.
What replaced the vacuum tube?
Transistors transformed the world of electronics and had a huge impact on computer design. Transistors made of semiconductors replaced tubes in the construction of computers. By replacing bulky and unreliable vacuum tubes with transistors, computers could now perform the same functions, using less power and space.
Does the US military still use vacuum tubes?
Christensen estimates that more than 180,000 microwave vacuum electronic devices are currently deployed in some 270 fielded DOD systems.
What vacuum tubes are made in Russia?
Sovtek is a brand of vacuum tube owned by Mike Matthews’s New Sensor Corporation and manufactured in Saratov, Russia. They are often used in guitar amplification and include versions of the popular 12AX7, EL84, EL34, and 6L6 vacuum tubes.
How can you tell if a vacuum tube is bad?
When a vacuum tube develops an air leak (a small crack or bad seal by a pin for example) this getter color will change to pure white. If you see this you know with 100% certainty that the tube is bad. Third, look for a purple glow that is very focused around specific elements inside the tube.
How do I know when my tubes need replacing?
These are the most common signs that tubes need replacement.
- Excessive noise (hiss, hum) including squealing or microphonic tubes.
- Loss of high end. Little or no treble.
- A muddy bottom end.
- Erratic changes in the overall volume.
- A blown H.T.
- The amp doesn’t work!
Do antique radios still work?
Most antique radios will work once the capacitors have been replaced. If it does not work then signal trace through the circuit by injecting a signal at the IF or RF, replacing resistors or occasionally a tube where needed. Old resistors have a tendency to increase in value with age.
What can you do with old radios?
Some centers might come to your home to pick up electronics, while others will want you to drop them off yourself. Load the box of electronics into your car and drive to the recycling center if it doesn’t perform pick-ups. Drop off the electronics with a recycling center employee.
Why are vacuum tubes not made in USA?
Are all tubes made in Russia?
There aren’t many vacuum tubes made outside Russia and China, and so prices could sky rocket throughout 2022. The only USA manufactured tubes I could think of are Western Electric, for example, and JJ tubes in Slovakia.
What is the largest vacuum tube?
One Cold War tube that is still going strong is the huge ring-bar traveling-wave tube. This high-power tube stands over 3 meters from cathode to collector, making it the world’s largest TWT.
How do I choose a vacuum tube?
Below are some recommended tips to implement to make the process go smoother.
- Markings matter. Each vacuum tube is stamped with a unique identification marking.
- Fit is not a performance indicator.
- Deal with a trained specialist.
- Know your budget.
- Selling site matters.
- Understand the JAN designation.