Abstract: A system for linking adjacent cuff sets for boiler tubes in parallel. A pair of contoured, plate-like adapter links is shaped to fit over the endmost cuff portions of two endwise mated cuff sets, and then secured to the endwise mated cuff sets to hold them in parallel. In a preferred form the adapter links are radially connected by a male throughpiece such as a bolt or bar extending through a keyway formed integrally in the end faces of the mated cuff sets. In a further preferred form, the end cuff portions of the mated cuff sets include welding tangs adapted to fit into welding slots formed in the adapter links so that the adapter links can be welded to the tangs, thereby locking the mated cuff sets together in a lengthwise direction.

Abstract: In a power line carrier telephone extension system for transmitting electrical signals between the telephone line and an extension telephone over the AC electric power line available at a telephone subscriber's premises, that includes a main station for processing signals between the subscriber's telephone line and power lines and two or more extension telephones of the system that plug into the power line, means that provides for two or more of the system telephones to communicate without going on the telephone line (Intercom), even while another system telephone is engaged in an outside telephone call and means are further provided for all telephones of the system to conference in Intercom.

Abstract: In a power line carrier telephone extension system for transmitting electrical signals between the telephone line and one or more extension telephones over the AC electric power line available at a telephone subscriber's premises, that includes a main station for processing signals between the subscriber's telephone line and power lines and one or more extension telephones of the system that plugs into the power line, all of which can place calls to the telephone line, answer calls from the telephone line and conference together in full duplex communication, means at the extension telephones for initiating a telephone line hold signal that is transmitted over the power line to the main station where the hold signal is detected and initiates connecting a hold impedance across the telephone line.

Abstract: A power line telephone extension system for carrying electrical signals between a subscriber's telephone line of a conventional telephone communication system and the subscriber's remote transmit-receiver device, (such as a conventional extension telephone), over the AC electric power wires available to the subscriber which includes: master linking circuits for processing signals between the subscriber's telephone line and the AC power wires; extension linking circuits for processing signals between the AC power wires and the subscriber's remote transmit-receive device, such as a conventional extension telephone; and a directional coupler circuit electrically coupling the remote transmit-receive device and the telephone line. The extension system is quite suitable for use with the presently available, well known, conventional extension telephone that plugs in by the plug (modular or 4 prong) provided therewith, to the directional coupler.

Abstract: A power line telephone extension system for carrying electrical signals between a subscriber's telephone line of a conventional telephone communication system and the subscriber's remote transmit-receiver device, (such as a conventional extension telephone), over the AC electric power wires available to the subscriber which includes: master linking circuits for processing signals between the subscriber's telephone line and the AC power wires; extension linking circuits for processing signals between the AC power wires and the subscriber's remote transmit-receive device, such as a conventional extension telephone; and a directional coupler circuit electrically coupling the remote transmit-receive device and the telephone line. The extension system is quite suitable for use with the presently available, well known, conventional extension telephone that plugs in by the plug (modular or 4 prong) provided therewith, to the directional coupler.

Abstract: In a power line carrier telephone extension system for transmitting electrical signals between the telephone line and an extension telephone over the AC electric power line available at a telephone subscriber's premises, that includes a main station for processing signals between the subscriber's telephone line and power lines and an extension telephone of the system that plugs into the power line, means that provides for a plurality of such extension telephones all of which can place calls to the telephone line, answer calls from the telephone line and conference together in full duplex communication.

Abstract: A remote transmitting or receiving device (T/R device) communicates with a conventional subscriber telephone through available AC power wires which carry signals that may be modulations of RF carrier frequencies and which are coupled to the power wires. For example, an incoming telephone call includes signals that are detected and modulate a master RF carrier frequency which is coupled to the AC power wires at the telephone line location and these signals are coupled from the AC power wires at a remote R device location, and, demodulated and used to control an electrical appliance, motor, pump, etc. The remote T device which may be, for example, a fire detector produces signals which modulate a remote RF carrier frequency which is coupled to the AC power wires at the remote location and this modulated carrier is coupled from the AC power wires and demodulated at the telephone line location to control or initiate signals in suitable form for transmission over the telephone line.