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Definition of Terms
AMPEREAn ampere (current) is a (coulomb/second).
BANDWIDTHDifference in frequency between the upper and lower 3dB down response frequencies.
BI-PHASEFound as a power feed to most U.S. homes. Derived from a center tapped transformer, it contains two hot phases (180°) with a center tap neutral return. Normally supplied as two 120 volt single phases with 240 volts available across both phases. The neutral return is usually earth grounded.
CAPACITANCEMeasured at 1.0kHz unless otherwise stated.
CLAMPTo clip. To hold turn-on voltage as current is increased. Turn-on voltage is the same, or nearly the same, as “on” voltage drop.
CLAMPING RATIOThe ratio of voltage drop at a given current to the turn-on voltage.
CLAMPING SPEEDMeasured with full lead length using a 1kV/ns waveform in a 50½ system, with ³300MHz or larger bandwidth.
COMBINERThe summation of multiple transmitters into one transmission line. The peak voltage from each signal will be additive and will be higher than the sum of the power would indicate.
COMMON-MODEPertaining to signals or signal components referenced to ground.
COULOMBMeasurement of charge. Often used to indicate the amount of transferred charge through a gas tube to determine gas tube life. “Q” abbreviation. A coulomb is (current x time).
CROWBARTo turn-on and clamp close to ground level. Having a high turn-on trigger voltage and a low “on” voltage.
DIFFERENTIAL MODEReferenced only between conductors (not referenced to ground).
DIPLEXER(TV Broadcasting). The combining of two transmitters into one transmission line. TV visual and aural.
DUPLEXERSimultaneous receive and transmit on one transmission line. Where a T connector splits/combines the signals to two groups of filters. The receiver filter passes the receive frequency while rejecting (band stop) the transmitter’s frequency. The transmitter filter passes its frequency while attenuating the Class C transmit noise at the receive frequency.
EMI/RFIElectro Magnetic Interference/Radio Frequency Interference. Broad spectrum noise or interfering signals.
EMPElectro Magnetic Pulse, usually referred to as the manmade generation by detonation of a nuclear bomb at a high altitude, which generates a very fast pulse (RF) which can be captured by antennas and long unshielded lines. Sometimes referred to as NEMP, HEMP, etc. Lightning can also generate an EMP near the event. Referred to as LEMP.
EMP RATEDRated as having a fast enough turn-on time or filtering to protect against the effects of an EMP event.
FARADAY SHIELDAn electrostatic (E field) shield made up of a conductive or partially conductive material or grid. A Faraday cage or screen room is effective for protecting inside equipment from outside radiated RF energies.
FILTERING (EMI/RFI) Measured in a 50½ system — loaded. As per MIL-STD-220.
FREQUENCY RANGEThe bandwidth over which both the listed maximum VSWR and Insertion Loss specifications are valid.
GROUND IMPEDANCEThe ground resistance and the inductance/capacitance value of the grounding system. Also called dynamic surge ground impedance.
GROUND LOOPAn undesired potential EMI condition formed when two or more pieces of equipment are interconnected and earthed for shock safety hazard prevention purposes.
GROUND RESISTANCEThe resistance value of a given ground rod or grounding system as measured, usually by a fall of potential (3 stake) method, using a 100Hz signal source.
HFHigh Frequency – normally from 3 to 30MHz, however in this catalog it covers from 1.5 to 30MHz.
HOUSED USE ONLYFor indoor use, or must be further enclosed or rain-proofed for outdoor usage.
IMPEDANCENominal impedance of the device. The variation of this impedance with frequency is measured as VSWR.
IN-LINEPower or signal passage through unit. In series with line. Usually a multi-stage protector. Best protection method.
INSERTION LOSSLoss of a device across the stated frequency range. This type of loss is due to the insertion of the unit in series with a signal path.
JOULESA unit of energy. One joule for one second is equal to one watt of power. Joules is (current x time x voltage).
LEAKAGE CURRENTUsually measured at 50 or 60Hz with 120, 240 or 480 volts ac. However, it can be ac or dc at a specific voltage and frequency.
LOOP RESISTANCETotal resistance as measured across the input with the output shorted.
MAXIMUM PEAK LET-THROUGH VOLTAGEMeasured at a given surge current using a given waveform, and using ³300MHz bandwidth across a 50½ impedance. (Note: this 50½ impedance may be dc blocked [large bandwidth compared to the surge frequencies present] and 50½ resistive load [termination]).
MAXIMUM POWERMaximum Continuous Wave (CW) transmit power, without unit degradation.
MAXIMUM SURGEThe maximum single surge current and specified waveform that can be handled by a device without failure during the conduction of that waveform and which ends the life of the device for conducting successive waveforms, but does not allow any generation of outward projectiles.
MULTI-STRIKE CAPABILITYIn most applications current sharing will occur, and in a direct strike event the unit will survive to work again.
POWERPower is (voltage x current) or a (coulomb/second).
RECEIVER MULTICOUPLERSometimes with an amplifier, this device has one antenna line and multiple outlets.
RFRadio Frequencies — any and all frequencies that can be radiated as an electromagnetic wave (plane wave).
SAFETY GROUNDThe local earth ground. The earth ground which grounds the neutral return. The wire may be green or bare and can be through a metal conduit. It may be earth grounded as many times as needed. (Neutral must only be grounded once at the entry location).
SHFSuper High Frequency – from 3000MHz to 30GHz.
SHUNT PROTECTORLine-to-ground. No power or signal passage through unit. Not in-series with line.
SINGLE PHASEA true single phase supply. Usually a two-wire system with one hot phase and a neutral return. A safety earth ground is also present.
SKIN EFFECTThe gradient conduction and propagation of RF or RF components of a surge on the outer surfaces of conductors.
TEMPERATUREThe extremes of operating or storage that the unit or unit parts have been tested to under MIL-STD-202 for thermal shock.
THREE PHASEIt consists of sinusoids 120° apart on at least three wires (Delta) and often four wires (Wye). The fourth wire is a grounded neutral return. In a Delta system there is no reference to ground and thus it is more susceptible to lightning problems.
THROUGHPUT ENERGYThe total energy that will be let through the device using the indicated surge waveform.
TOTAL SURGE ENERGYTotal sum of surge energy for all lines of a protector unit. Measured in joules. The minimum total energy which results in the failure of the unit.
TRANSFER IMPEDANCEReferring to coax, is the impedance to transfer into or outside the coax at various frequencies usually below 1MHz. Due to loss of skin effect attenuation or shielding at these low frequencies, coax can be susceptible to interference and noise as well as the radiation of such signals.
TURN-ON TIME – GAS TUBEThe amount of time that exists in the period that occurs when the ramp voltage barely exceeds the turn-on voltage of the device, and the point at which 50% of the peak voltage is achieved during the turn-on (crowbar) process. Measured in a 50½ system with ³300MHz bandwidth.
TURN-ON VacThe maximum ac sine wave voltage that can be passed with the peaks just at the turn-on Vdc level.
TURN-ON VdcTurn-on voltage at 1mA dc with a ramp of 100V/ms typical.
UHFUltra-High Frequency – normally from 300 to 3000MHz, however in this catalog we breakout 800 to 1000MHz separately even though it is within this category.
VHFVery High Frequency – from 30 to 300MHz.
VLFVery Low Frequency – from 300Hz to 3kHz.
VOLTA volt is a (joule/coulomb).
VSWRVoltage Standing Wave Ratio (VSWR) of the device across the stated frequency range. VSWR is the amount of reflected signal due to an impedance mismatch.
VT MAXThe max peak voltage of all combined waveforms. Vtotal is used for multi-coupled or combined transmit signals.
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