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Sales Bulletin  1104001
Blanking & Gating at AR Modular RF division

1. Blanking (Manual and Remote)

  • Basic Blanking is provided on most systems and is evident by the “Blanking Push Button” on the amplifier chassis front panel.
  • The manual pushbutton provides control to a relay interface that activates the internal gating control lines.
  • Remote blanking is achieved via optional RS232 and/or IEEE488 interface that activates the internal gating lines. Amplifier systems without the optional IEEE-488 interface for RS-232/IEEE488 control usually include a remote control connector, which also provides the ability to activate the blanking control signal.
  • Blanking is considered a slow control and has a response time of 200-1000 milliseconds. It is not a repetitive/synchronized interface with RF input signals. When RS-232 or IEEE488 are used, blanking is not a time deterministic action.
  • Its primary purpose is to provide a simple manual or remote means of turning off and on the RF output power of the amplifier, and can be used to reduce power consumption or heat production at times when the amplifier can be disabled.

2. Internal Gating

  • Internal gating is the core method of controlling the amplifier system. It is typically an analog control of the last amplifier stage(s) of each module (driver or PA) in the system.
    Shorting this control line to ground level inhibits the amplifier output by removing gate bias from these final stages.
  • Internal gating is activated by controlling items, such as, over temperature switches, front panel blanking switch, optional RS232 and/or IEEE488 control, as well as, optional external gating (standard or high performance) and optional door interlock sw connection. (High VSWR trip point and ALC are controlled by an input attenuator and are not associated with the internal gating.)

3. External Gating Option (Standard Type)

  • The External Gating Option provides a connection to the internal
    gating via a BNC connector and doesn’t use a relay interface.
    (This gating connection can be also labeled as “Door Interlock”
    or be provided as a second gating connection.)
  • The External Gating Option has a unspecified or coarsely specified response time on the order of up to 1 millisecond, a speed which includes moderate effects of essential: bypass filtering capacitors, inductors, and coaxial cabling. Faster gating speeds (100usec) may be available on special order depending on the system frequency range, size and configuration.
  • The External Gating Option’s primary purpose is to provide precision amplifier control of the transmissions used by medical radiation, industrial cleaning processes and so on. The gating controls the “off period” of the transmission to meet the end users requirements without specific regard to the noise performance during that “off period”.

4. External Gating Option (High Performance)

  • High Performance External Gating is via a BNC control interface and also controls the last active stages of the system’s modules.
  • It utilizes a special multi-port gating card, in conjunction with
    50 ohm terminated low noise control lines to distribute all control
    to the modules.
  • Its response time is in the order of 1 to 2 microseconds. It has both fast attack and fall times.
  • Its primary purpose is to provide precision amplifier gating of the transmissions used by “imaging systems” of all kinds. The gating controls not only the “off period” but also the “off period” noise level, which is vital for imaging systems that need to listen for echo responses during the off period. Applications are NMR, MRI, and Radar systems.

5. General Note

  • Pulse Amplifiers may use either the Standard External Gating option or the High Performance External Gating Option to achieve lower power supply current requirements for Class A /AB operation thus have lower cost and physically smaller power supplies and also achieve the economies and performance of lower system internal heat dissipation.