: Their high input impedance made them ideal for probe tubes in vacuum-tube voltmeters. 5. Collecting and Maintenance
Today, acorn tubes like the RCA 958 are sought after by collectors and restorers of vintage RF gear.
: Unlike standard tubes with pins at the bottom, acorn tubes have pins protruding from the "equator" of the glass bulb. acorn tube
: Featured in classic pre-war and wartime receivers like the Hallicrafters S-27 and National 1-10 .
: They require a ceramic ring socket where the tube sits in the central hole to maintain the short lead benefits. : Their high input impedance made them ideal
An (or acorn valve) is a specialized family of vacuum tubes developed in the 1930s to overcome the physical limitations of standard tubes at high frequencies. Named for their resemblance to the nut of an oak tree, they were critical for the development of early VHF/UHF (Very High/Ultra High Frequency) technology. 1. Why They Exist: The Frequency Problem
: They were quickly superseded in the mid-1940s by "miniature" 7-pin tubes and later nuvistors , which were even smaller and more rugged. SOCKETLESS TUBE CIRCUIT TECHNIQUES - J. W. Rush, Jr. : Unlike standard tubes with pins at the
: Long internal lead wires act as inductors and capacitors, distorting high-speed signals.