Tuned_circuit_of_shortwave_radio_transmitter_from_1938.jpg
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Summary
| Description |
English:
Output tank circuit (
LC circuit, tuned circuit
) of
power amplifier
of
shortwave
amateur
radiotelegraph
transmitter
from 1938. It consists of an
inductor
(coil, top)
connected in parallel with a variable
capacitor
(bottom)
. It serves as a
bandpass filter
, removing any harmonic frequencies from the output so they will not be radiated by the antenna. Since the output power is 1 kilowatt the voltage on the circuit is several thousand volts, so to prevent arcing the capacitor plates are more widely spaced than a low voltage capacitor, and the coil is mounted on standoff insulators. The tuned circuit must have a narrow bandwidth (high
Q
) to filter the narrow CW signal, and the coil shows high Q construction: it is made of a single layer winding with turns separated to reduce losses from
proximity effect
, of thick silver-plated wire to reduce losses from
skin effect
, suspended in air without a coil form to reduce
dielectric losses
.
|
| Date | |
| Source | Retrieved 7 June 2023 from Smith, W. W. 1938 The Radio Handbook , Radio, Ltd., Los Angeles, p.343 fig.24 on archive.com |
| Author |
W. W. Smith Uploaded by: Chetvorno |
|
Permission
( Reusing this file ) |
This book published in the US in 1938 would have the copyright renewed in 1966. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here [1] . Search of the Renewals for Periodicals for 1965, 1966 and 1967 show no renewal entries for The Radio Handbook . Therefore the work's copyright was not renewed and it is in the public domain. |
| Other versions | Vacuum tube HF300 shortwave RF power amplifier from 1938.jpg picture of the complete amplifier |
Licensing
|
This work is in the
public domain
because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the
copyright was not renewed
. For further explanation, see
Commons:Hirtle chart
and
the copyright renewal logs
. Note that it may still be copyrighted in jurisdictions that do not apply the
rule of the shorter term
for US works (depending on the date of the author's death), such as Canada (70 years
p.m.a.
), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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