science

WD-11

WD-11 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand WD-11 rather than just read about it. In short: The WD-11 vacuum tube, a triode, was introduced by the Westinghouse Electric corporation in 1922 for their Aeriola RF model radio and found use in other contemporary regenerative receivers (used as a detector-amplifier) including the Regenoflex and Radiola series. The WD11 and "RCA-11" (and later simply named "11" by RCA and Philips/Miniwatt) have the following characteristics: Drawbacks The design of the WD-11 is s…

Key takeaways

WD-11 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WD-11 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WD-11 from memory before moving on to harder problems.

Reference excerpt

The WD-11 vacuum tube, a triode, was introduced by the Westinghouse Electric corporation in 1922 for their Aeriola RF model radio and found use in other contemporary regenerative receivers (used as a detector-amplifier) including the Regenoflex and Radiola series. The WD11 and "RCA-11" (and later simply named "11" by RCA and Philips/Miniwatt) have the following characteristics:

Drawbacks

The design of the WD-11 is somewhat flawed. When the filament burns out, it has a tendency to contact the plate. This feeds high voltages back through the heater circuitry, subsequently burning out the filaments on the remaining tubes. The WD-11 has a unique 4-pin base layout that was unlike any subsequent UV and UX style tube bases. It had 3 "small" pins and one "large" pin. Later UV based tubes relied on an index pin on the side of the tube base and UX tubes had 2 large and 2 small pins to ensure proper indexing. It was replaced a year after its introduction by higher performance tubes which were less likely to encounter the filament shorting problem, Westinghouse Electric's WD-12 and General Electric's UX-199. No radios using the WD-11 tube were designed after 1924. RCA ceased production and issued a service bulletin describing how to retrofit existing sets to use the newer UX-199 triodes.

Collectibility Because of the rarity of the WD-11, it has become one of the most valuable vacuum tubes in the world. New-old-stock tubes have sold for as much as US$180 and used tubes have sold for over $100, more than the original price of the radios that use them. Collectors rarely use these tubes for fear of burning them out.

Substitution Sets that use the costly WD-11 and UV-199 tubes can be modified to use the inexpensive 1A5/GT octal power pentode by wiring a 5.1 ohm resistor between the pins of the filament and fabricating an octal-to-four pin adaptor. The pin for the 1A5's suppressor is left unconnected and the screen connected to the plate. The type 12 (also known as RCA-12) is electrically identical to the type 11, but with a more common UX4 base.

External links Data sheet for WD-11 Here is a link on how to modify other tubes to use in place of a wd11:

https://www.6v6.co.uk/vcomp/tech_tips/wd11.htm

Illustrations

Worked examples

Example 1 — a first encounter with WD-11

Start with the simplest possible case. Write down what WD-11 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to WD-11 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about WD-11 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of WD-11

In research: WD-11 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses WD-11 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: WD-11 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Vacuum tubes, so understanding it makes those chapters shorter.
In everyday life: Look for WD-11 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study WD-11 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WD-11 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain WD-11 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WD-11 in simple terms?

Why does WD-11 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study WD-11?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on WD-11.