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Filament and piąte Controls are separate pushbuttons on the front panel, with a built-in 120-second delay between filament and piąte initiation to allow for tubę warmup. Overload sensors are located in botn the driver and finał sections of the amplifiers, as well as in the transmission linę to detect abnormally high vswr. After tripping, the recycle Circuit will attempt to start the transmitter again, either two or four times in a 30-second time period after failure. If, after that time, the overload condition still exists, the transmitter will remain off, and indicator lamps will show where the malfunction exists.

The reliability of the Collins 831 H-1/1B is enhanced by the use of solid State components with the exception of the driver and finał amplifier tubes. A neutralized power amplifier improves stability, and minimizes tuning and loading adjustment problems.

The entire transmitter is contained in two cabinets, the only external components being those associated with the combiner and optional automatic switching gear. The Collins 831 H-1/1 B Transmitters provide the broadcaster with a truły redundant system that offers the flexibility that enables fuli time operation with a minimum of "down time." This, coupled with Collins 24-hour field service operation, and unparalleled warranty, give morę value per dollar than any competitive system on the market.

831H FM Transmitter

As an option, an automatic switching system consisting of the 377C-1 Exciter Control. and the 377D 1 Combiner Control, is available to facilitate a completely redundant operation. These units monitor all parameters of operation, and make decisions as to what exciter/transmitter/antenna combinat.on will give best service in the event of equipment failure. A complete description of the system options follows this section.

Before our transmitters are shipped to a customer, they are set up on the exact frequency that will be used in operation, and tested at fuli rated power for extended periods of time, in a lab that provides every conceivable operating condition. After it has been determined that the unit satisfies every stringent Collins standard, it is packaged and shipped to the installation site, complete with all test data. and instructions for installation.

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