Electronica

SECTION 1 DESCRIPTION

ELECTRICAL

The transmitter is a conservatively rated, single channel, high level amplitude modulated. It is designed to provide 24 hour per day, unattended continuous service in broadcast and communication applications. The standard frequency range of the equipment is 535 to 1620 KC. However, on a custom basis, the transmitter can be supplied on any carrier frequencybetween 150 KC and 10mc.
Referring to the block diagram of the equipment it can be seen that the transmitter consists of a conventional crystal oscillator, intermediate power amplifier, and a class C power amplifier. Due to the selection of conservatively rated components and tubes, the transmitter is capable of achieving, on a continuous basis, 1200 watts of RF carrier output. A communicationversion of this transmitter is available with a carrier output power of 1500 watts.
The power amplifier of the transmitter is amplitude modulated by utilizing conventional high level modulation and self modulating screen circuitry.
The nominal audio input required for 100% is 0dbm.
The control ladder is so designed that operation of the equipment is achieved by simply operating front panelswitches. This circuitry can also be actuated by utilizing a conventional remote control system. Sampling resistors, with wires brought out to accessible terminal boards, permit remote control monitoring of meter without any interference with the operation of the transmitter.
All power supplies within the equipment utilize conservatively rated silicons which are operated at one-half of theircurrent and voltage ratings. Special precautions have been taken to protect these elements from damage due to line surges or transients.

MECHANICAL

The complete unit is contained in a medium sized , modem styled cabinet. The entire equipment occupies approximately 7.5 square feet of floor area.
Access to all parts can be easily obtained by entrance through the rear interlocked door and the RFcompartment covers.

Construction of the transmitter has been such that vertical panel construction is emphasized.
Thus, blind spots caused by shelf type assembly are reduced to a minimum. In practically all case, every part can be seen at a glance by simply opening the appropriate entrance door.
Attractive, rugged, full sized meters are prominently displayed on the front of the cabinet.These meters indicate the status of every major circuit in the equipment. Access to all circuits which contain exposed terminals with 300 volts or greater is accomplished through interlocked doors. This fact, together with acting bleeder circuitry, protect personnel from unintentionally harming themselves from electrical potentials.

To facilitate production and service, a modular type ofconstruction is utilized in this transmitter.
The heavy transformer and reactors are located on the base of the cabinet. The lowest vertical panel contains the rectifiers, filters and other components of the low voltage( L.V) and high voltage (H.V) plate supplies. This is called the “RECTIFIER” panel.

Immediately above is located a CONTOL PANEL which contains all control switches, fuse,indicator lights, control relays, overload recycle system. It also included the bias supply and the filter components associated with the LV plate supply.

Next come the EXCITER panel; which contains all the audio circuitry uo the grid the final modulator tubes, v3 and v4, including the controls to set the bias of v3 and v4.

The right side of the exciter contains the oscillator anddriver stages. The socket of the tube, v6, is located on the top flange of the exciter panel, such that the tube itself protrudes into the PA BOX.
The PA BOX cubicle is entirely. It contains the RF circuitry of the plate of the driver stage and all the elements associated with the final amplifier, v7, v8. It also includes the modulator tube v3, v4 and associated circuitry.
On top of the PA BOX is...