Re: K carrier info wanted
- more "K" trivia; after 50 years its comes back slowly,fragmented even.
primarily for those who have'nt dug into the references cited.
K aux stations had a type A alarm system to one of the adjacent terminals using DC signals on cable pairs; any of 10 alarm conditions signals the terminal office with an audible alarm & lighting 1 or more of 10 lamps in a jackfield. Typical alarms assigned to lamp numbers were: 152V power plant high-low voltage, AC PWR fail,rectifier fail,open door, high-low building temp,blown fuse,low back-up grid battery(dry cell).The only "command" that could be sent to the station was a rescan; which was often done during maintenance activities and always after a tech finished the repairs and closed the door.
The station batteries were only good for about 5-8 hours, and a sustained(15-30 min) AC power failure mandated a trailer mounted 10KW alternator sent out to power the station.
K carrier required emergency grid batteries(C) in case of power failures.This was supplied by a string of 1.5V "Blue Bell" dry cells(remember Fahnestock clips?);by the 1970's, probably one of the last telephone applications of this battery(from 1916).
Some stations included reversable type 12 VF program amps(repeaters)
carrying 5/8KH network radio service; and as mentioned, "N"/"ON" carrier repeaters and/or terminals.
The original K routes(K1) used a pilot wire in the cable to sense resistance changes due to temperature variations and adjust flat gain via a "pilot wire regulator", a precision galvanometer device(made by Leeds & Northrup) controlling autosyn(aka selsyn,synchro)motor gain controls in line amps. Later K2 was implemented using 12,28,56 & 60KH line pilots to adjust flat,bulge & slope equaization via thermisters in feedback loops.
K carrier testsets were WeCo 17B oscillator,31B TMS(selective voltmeter), 30A thermo-couple power meter; jack field was 135 ohm double plug for shielded patch cords.
Previous posts have mentioned Naval Radio Station NSS(Annapolis)VLF signals audible in some K systems along the mid east coast; this was apparently due to longitudinal unbalances,high resistance leaks,non-linearities, etc in the stations or cable(especially aerial). Anyone know if this occured in New England near NAA Cutler? or in the NorthWest near NLK Jim Creek?