Tech's Filing Cabinet Miscellaneous General Electric RCA Tube Tech Semi Tech Audio Radio Components

Scanned articles covering general radio technical topics. Unless otherwise noted, these scans were done by John Atwood. Articles marked "*" were extracted from worldradiohistory.com (formerly americanradiohistory.com) scans. scans. Listed chronologically.

Armstrong 1915 Some Recent Developments in the Audion Receiver - A summary of Armstrong's receiver designs using the audion, as presented in the Proceeding of the I.R.E. It is followed by a "discussion" (by letter) between Armstrong and Lee DeForest. Reading this, it is clear that: a.) DeForest's concept of how the audion works is clouded by misconceptions and random behavior, and b.) Armstrong's conception is crystal-clear and accurate. Scan by Google.

Hazeltine 1923 Tuned RF Amplification with Neutralization of Capacity Coupling - Prof. Hazeltine's Neutrodyne circuit described. This permitted radio manufacturers to produce economically viable tuned-RF (TRF) receivers without having to license the RCA radio patents.

Armstrong 1924 The Superheterodyne - Its Origin, Development and Some Recent Improvements * - Review of the invention of the superheterodyne receiver and efforts to cost-reduce it and commercialize it.

Dreyer Jr 1924 Solving the Problems of the Neutrodyne - Details on implementing and adjusting the Hazeltine neutrodyne circuit.

Crosby 1939 Communication by Phase Modulation * - Implementation and performance tests on phase modulation. Not much used at the time, but forms the basis of the phasing system of SSB and the I-Q modulation used in modern communications systems.

FM 1940 Police Radio History * - A short write-up of the introduction of FM to two-way police radios, first for the Connecticut State Police, then for the Chicago Police Department.

Eastman & Woodward 1941 Binaural Transmission on a Single Channel * - Amplitude and phase modulation of the same channel - essentially the I-Q system used in modern communications systems.

Batcher 1945 Thermal Stability in Receiver Oscillators-I and Batcher 1945 Thermal Stability in Receiver Oscillators-II * - A good tutorial on what causes oscillator drift and how to minimize or compensate this effect.

QST RCA 1947 Transmitting Ratings on Receiver Tubes - A table of class-C transmitter ratings for the 6AG7, 6AK6, 6AQ5, 6C4, 6F6, 6L6, 6N7, 6V6GT, and 12AU7. These are only for amateur use, and are not listed in regular tube manuals or data sheets. Gives screen-grid amplification factors and capacitances.

Goodman 1947 How Sensitive is Your Receiver? - Using a diode noise generator for measuring the noise figure of a receiver front-end. This article is based on information directly from the MIT Rad Lab.

QST 1948 A High-Stability Oscillator Circuit - Details on a high-stability VFO circuit first described by Clapp in the Proceedings of the I.R.E.

QST 1948 The Clapp High-Stability Cicuit - Comments from Clapp himself on the differences between his circuit and an early VFO by Seiler (1941).

Tapley 1949 Some Notes on the Clapp Oscillator - Practical design notes on implementing the Clapp oscillator.

Sainsbury 1954 New Developments in HF Receivers * - Overview of radio receivers used in point-to-point operation in the UK and British empire.