Electron-coupled oscillators (ECOs) were a real breakthrough in achieving frequency stability in harsh environments that included mechanical vibration, temperature excursions, power supply variations, and load changes. Use of vacuum tubes made the task even more challenging. Such oscillators were necessarily very expensive compared to less sophisticated designs. Henry E. Rice Jr., W9YZH, introduced his "Rice Variarm" model (aka the Millen Model 90700) at a breakthrough price of just $29.50, which in 2013 money equates to $469.89 per the U.S. BLS Inflation Calculator. That is a lot of moola for amateur radio operators even today. The arm sticking out of the case is for adjusting the frequency.
February 1941 QST
Wax nostalgic about and learn from the history of early electronics. See articles
QST, published December 1915 - present. All copyrights hereby acknowledged.
Something Radically New in ECOs
There are many approaches to the ECO design, most of them having been described in the past; such as expensive, ruggedly-built h.f. oscillators with their external regulated power supplies, low-frequency dual heterodyne oscillators, etc. All have their merits, but are necessarily expensive to manufacture and must ultimately end up by selling in the 50 to 60 dollar price bracket.
A new approach to this problem has been evolved by Henry Rice, Jr., and was described in detail in January OST. Probably the outstanding feature of the Rice development is its high-performance-per-dollar which makes possible a factory built commercial ECO with modern performance, complete with tubes, ready to use, for less than 30 dollars!
Posted November 6, 2013