science

SY4307A

SY4307A 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 SY4307A rather than just read about it. In short: The type SY4307A is the STC version of the Western Electric 307A, a power output pentode possessing a similar power rating, but significantly different characteristics to the far more common type 807 thermionic valve/vacuum tube. The "SY" prefix denotes the site of manufacture as being Sydney.

Key takeaways

SY4307A belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SY4307A to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SY4307A from memory before moving on to harder problems.

Reference excerpt

The type SY4307A is the STC version of the Western Electric 307A, a power output pentode possessing a similar power rating, but significantly different characteristics to the far more common type 807 thermionic valve/vacuum tube. The "SY" prefix denotes the site of manufacture as being Sydney. The plant, operated by Standard Telephones and Cables Pty. Ltd. was located on Mandible Street in the suburb of Alexandria and existed under that corporate entity from 1937 to 1970. Although the remaining structure postdates the depicted device, this device was likely assembled on an adjoining property upon which the structures have been demolished and site re-purposed. Electrically equivalent devices marked "307A" were manufactured in North America by Western Electric and these possibly predate the Australian version.

Uses Although the 807 is used for both audio amplification, (usually class AB), and radio frequency amplification in the 1-30 MHz range, (usually class C), this type was usually used for the latter. This tube/valve is a pentode with a 'directly heated cathode', meaning that the cathode consists of an emissive oxide coated filament. These features suggest the 4307A could predate and is contemporary with, the 807 which is a beam power tetrode, a more advanced design with a more linear transfer characteristic and a more complex 'indirectly heated cathode'.

Similarity to 807 If the pinout of the 4307A is compared to that of the 807 the similarity is striking. All pins are assigned equivalent electrodes with the exception of pin 4, which is the suppressor grid, g3, in this type but in the 807 pin 4 is connected to the equivalent of a suppressor grid, the 'beam plates' and also the separate indirectly heated cathode. It is possible to interchange the two with the relatively minor alteration involving the linking of pins 4 and 5 and ensuring the heater supply is floating (not connected to other heaters). If the heater is supplied from an A.C. source, linking pin 4 to the centre of that source and the cathode bootstrap minimizes hum pickup.

Historical significance The STC/Brimar-made SY4307A was used extensively during World War II by the Australian armed forces and the example depicted is marked on the Bakelite collar of its base with the "D broad arrow D" commonwealth department of defense mark. Two SY4307As were used, wired in parallel, as the output stage, or "final", in a transmitter constructed clandestinely by the Australian soldiers of Sparrow Force in Japanese occupied Portuguese Timor in 1942. This transmitter became known affectionately as "Winnie the War Winner Archived 2009-05-16 at the Wayback Machine", named after the British wartime Prime Minister, Winston Churchill.

Illustrations

Worked examples

Example 1 — a first encounter with SY4307A

Start with the simplest possible case. Write down what SY4307A 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 SY4307A 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 SY4307A 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 SY4307A

In research: SY4307A 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 SY4307A 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: SY4307A 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 SY4307A 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 SY4307A in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SY4307A 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 SY4307A out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SY4307A in simple terms?

Why does SY4307A 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 SY4307A?

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 SY4307A.