Centralab 823-AN N650 Vintage Ceramic Trimmer Capacitor 20-125 pF

Vintage Centralab 823-AN adjustable ceramic trimmer capacitor with a nominal capacitance range of 20-125 pF.

This classic RF trimmer uses a ceramic body, rotary compression adjustment, large solder terminals, and chassis mounting holes. The component is marked 823AN, 20-125, N650, and carries the original CRL Centralab identification.

The N650 marking identifies a negative temperature coefficient of approximately -650 parts per million per degree Celsius. Temperature-compensating capacitors of this type were specifically useful in RF and oscillator circuits where engineers needed controlled capacitance change to offset temperature-related drift elsewhere in the circuit.

Period Centralab specifications identify the 823-AN as a 20-125 pF ceramic trimmer rated for 600 VDC working service with a 1200 VDC test rating.

The 823-AN was intended for RF tuning, oscillator adjustment, filter alignment, transmitter and receiver circuits, communications equipment, amateur-radio equipment, and other applications requiring stable adjustable capacitance.

LIFECYCLE STATUS: DISCONTINUED

HISTORICAL BACKGROUND:
Centralab was one of the major American electronic-component manufacturers of the vacuum-tube and early semiconductor eras. Operating as a division of Globe-Union, Centralab produced ceramic capacitors, variable resistors, switches, packaged circuits, and other components used throughout radio, television, communications, military, industrial, and laboratory electronics.

The 823 series of ceramic trimmer capacitors was already established by the late 1940s and early 1950s. Period electronics advertising specifically identifies the Centralab 823-AN as a 20-125 pF trimmer with a negative 650 temperature coefficient.

This temperature-compensating characteristic was important in precision RF design. Oscillator coils, fixed capacitors, and other circuit components can change slightly as temperature changes. Engineers could deliberately select a capacitor with a known negative temperature coefficient to counteract those effects and improve frequency stability as equipment warmed up.

The 823-AN has documented use in professional communications and transmitting equipment.

A 1951 Gates 250-watt broadcast-radio station parts list specifically identifies the Centralab 823-AN 20-125 pF ceramic trimmer in its circuitry. Components of this type were used during an era when commercial broadcast transmitters were built around vacuum tubes, high-voltage power supplies, tuned RF networks, and individually aligned stages.

The same exact Centralab 823-AN is also documented in the RCA SSB-1 single-sideband transmitter-receiver system. In later production versions of that equipment, four 20-125 pF 823-AN capacitors were specified for tuning the FL201 and FL202 filter circuits.

That documented communications-equipment history makes the 823-AN more than a generic variable capacitor. It represents the period when ceramic temperature-compensating trimmers were important precision components in transmitters, receivers, filters, and other professional RF equipment.

Centralab's 823-series construction used a substantial steatite ceramic body and mechanically rugged adjustment system. These components were designed during a period when electronic equipment was expected to be aligned, serviced, and repaired at component level by technicians.

Original Centralab 823-AN trimmers remain useful today for vintage transmitter and receiver restoration, amateur-radio construction, RF filter repair, oscillator circuits, laboratory equipment, and historically appropriate restoration work where modern miniature trimmers may not match the original mounting style, voltage capability, or temperature characteristics.