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Dummy Loads

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Dummy Loads

  • Introduction To Dummy Loads
  • Tips On Load Selection

    Introduction To Dummy Loads

    ELECTRO IMPULSE, Inc. manufactures standard and custom loads for the broadcast and communications industry. These loads have power ratings from 1500 Watts average to 10 Megawatts peak power.

    We can meet any special load requirement you may have. As an example, here are some special loads which we have produced for both the military and industry:

  • 600,000 Watt air-cooled test load for a Very Low Frequency (VLF) shore station radio transmitter.
  • 10 megawatt pulse liquid cooled RF load qualified for military airborne applications.
  • Dry, forced-air cooled load for 400 KW continuous average power, up to 110 MHz.
  • Twin line (balanced input) loads for rhombic antenna outdoor use.
  • Low IM distortion loads allowing IM distortion measurements to -85DB.
  • These special requirements are typical of our ability to produce small or high volume loads on a special or standard basis with quick turnaround capability.

    Our standard product line of loads includes many state of the art designs. We pioneered the development of dry, forced-air cooled loads, for use up through FM broadcast frequencies, which are now extremely popular in the broadcast industry. Our DACT Series of loads was the first dry, convection cooled series. These types of loads have become extremely popular, both domestically and internationally, as the availability of tap water for cooling decreases, and the importance of reliability of a dry load is recognized.

    Tips On Load Selection

    1. Notice to Broadcasters:
    AM transmitters must be matched with a load that can handle the full carrier output, PLUS modulation. Therefore, a 10,000 watt AM transmitter requires a 15,000 watt load. For FM use, only the carrier output power needs be considered.

    2. Peak Power Ratings:
    All loads listed herein handle Peak Envelope Power (PEP) of up to twice the average power rating. However, higher peak powers, including pulse applications, require special consideration involving peak voltage and current, and peak energy levels (expressed in joules). Some of our loads can handle exceptionally high peak powers (such as most of our dry convection and forced air cooled loads). Please check with the factory whenever you have a pulse application.

    3. Average Power Ratings:
    All average power ratings listed herein are continuous except as otherwise noted. We guarantee the average power ratings of all loads as advertised.

    4. Dissipated Heat:
    The amount of RF power terminated by an air cooled load will be dissipated as heat into the space where the load is operating. Be certain to consider this additional heat load on air conditioning and cooling systems. Normally, when large loads are installed in transmitter rooms, a ventilation system is installed which matches the air flow of the load. This will effectively pull all of the heated air out of the room and is an acceptable method to maintain room temperature. During the winter this ventilation system may be shut off to provide an economical means of heating the room. Please consult with the factory for details on air flow and ventilation requirements. Do not connect an air duct to any load unless it is specifically designed for this application. Air exhaust ducts present an air flow back pressure to the load and reduce air flow. This can cause load overheating and failure. We can provide loads with ducted outputs for special installations upon request. Many loads, especially those which are dry, convection cooled, run hot under full power. Provide adequate clearance and ventilation when considering the installation location of a load. Also consider that any dry load will run cooler if forced air flow is provided for it.

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