Boonton 9240 RF Voltmeter - Manual (Page 13)

Boonton 9240 Series RF Voltmeter
• Dual Independent Channels. When equipped with the optional second measurement channel, the
instrument can display two CW signals simultaneously. Each channel is calibrated and all channel
parameters are channel-independent.
• Selectable Ranging. Any of eight measurement ranges, or autoranging, can be selected during
instrument setup. The selection will be held until it is changed, or until the instrument is turned
off. When measuring signals with levels that fall within a narrow range, selecting one specific
instrument range may reduce measurement time. Autoranging is useful if the RF signal level is
unknown, or if RF signals with widely varying levels are to be measured.
• Selectable Filtering. Measurement speed and display stability can be optimized through the use of
selectable filtering. Filter times can be adjusted up to 20 seconds maximum in 50 millisecond
increments.
• Zeroing. Automatic zeroing (nulling of offsets for the voltage probe and input channel) is done
independently on each range to eliminate zero carryovers.
• Wide Frequency Range. The calibrated frequency range of the instrument is determined by the
probe model used. The 952001B standard RF Probe provides calibrated measurementsfrom 10
kHz to 1.2 GHz with usable indications beyond 4 GHz. The optional 952016 low frequency RF
Probe provides calibrated response from 10 Hz to 100 MHz.
• Calibration Storage. Shaping and calibration data for each probe is contained in EEPROM within
its 951090 Sensor Data Adapter. When the probe with its Data Adapter is plugged into the 9240
RF Voltmeter, the shaping and calibration data is downloaded and applied to the measurement
automatically. It is not necessary to enter any data manually. Existing voltage probes can be used
with the 9240 by loading a blank Data Adapter with calibration data. No further calibration of the
probe is needed.
• Voltage Range. The 9240 uses three internal hardware ranges to achieve a dynamic range of 90
dB. The input levels can range from less than 200 microvolts to 10 volts. Display resolution is
selectable to 0.001 dB. Using the appropriate 100:1 Voltage Divider accessory, the voltage range
can be extended to 300 Volts. For the 952001 RF Probe, use adapter Model 952005 to extend the
voltage range to 300 V over a frequency range of 10 kHz to 20 MHz. The 100:1 divider cannot be
used with the 952009 (50 ohm) RF Sensor. For the purpose of compatibility with previous models
and preexisting calibration procedures, the input range is divided into 8 virtual ranges which
correspond to previous practice.
• True RMS Response. The waveform response of the RF voltage probe is true RMS for voltages
below 30 mV. This characteristic provides accurate measurements for all types of waveforms with
levels up to 30 mV or 3 V with the appropriate 100:1 Voltage Divider. The waveform response of
the probe gradually changes to a peak detecting response above 30 mV. Computer generated
shaping allows the instrument to display RMS readings above 30 mV. This is valid for nearly
sinusoidal waveforms. For modulated signals, accurate results can be obtained at high levels if the
modulation envelope is relatively flat, (e.g. FM, QPSK). For other modulation types (e.g. Am,
Pulse, CDMA), accurate results can be obtained below 30 mV. The equivalent peak sinewave
voltage can be displayed. It is 1.414 times the RMS voltage and 3.01 dB grater than the reading in
decibel units.
• Low Noise. The 9240 has been designed and constructed to minimize noise from all sources. A
line filter and RF tight enclosure reject outside interference. The probe cables are a special low
noise design; vigorous flexing causes only minor disturbances, even on low level measurements
Non-microphonic probes are used to lessen probe sensitivity to shock and vibration.
General Information
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