B+K precision 2165A, Инструкция по эксплуатации, Страница: 13 / 28

13
CONTROLS AND INDICATORS
This permits the detection of any spectral lines which are
within the maximum measurable and displayable
frequency range, if the center frequency is set to 500 MHz
for Models 2625 and 2630 or 250 MHz for Models 2615A
and 2620A. If the baseline tends to move upwards when
the attenuation is decreased, it may indicate spectral lines
outside the maximum displayable frequency range with
excessive amplitude.
15. SCANWIDTH (Models 2625 and 2630). The
SCANWIDTH selectors allow to control the scanwidth
per division of the horizontal axis. The frequency/Div. can
be increased by means of the
►
button, and decreased by
means of the
◄ button. Switching is accomplished in 1
-2-
5 steps from 100 kHz/div. to 100 MHz/div.
The width of the scan range is displayed in MHz/div. and
refers to each horizontal division on the graticule. The
center frequency is indicated by the vertical graticule line
at middle of the horizontal axis. If the center frequency
and the scanwidth setting are correct, the X axis has a
length of 10 divisions. On scanwidth settings lower than
100 MHz, only a part of the entire frequency range is
displayed.
When SCANWIDTH is set to 100 MHz/div. and if center
frequency is set to 500 MHz, the displayed frequency
range extends to the right by 100 MHz per division,
ending at 1000 MHz (500 MHz + (5 x 100 MHz)). The
frequency decreases to the left in a similar way. In this
case the left graticule line corresponds to 0 Hz.
With these settings, a spectral line is visible which is
referred to as
“Zero Frequency” . It is the 1st LO
(oscillator) which becomes visible when its frequency
passes the first IF filter. This occurs when the center
frequency is low relative to the scanwidth range selected.
The “Zero Frequency” is different in level in every
instrument and therefore cannot be used as a reference
level. Spectral lines displayed left of the “Zero Frequency
Point” are so called image frequencies.
In the
ZERO SCAN mode the spectrum analyzer operates
like a receiver with selectable bandwidth. The frequency is
selected via the
CENTER FREQ. knob. Spectral line(s)
passing the IF filter cause a level display (selective
voltmeter function).
The selected scanwidth/div. settings are indicated by a
number of LEDs above the range setting push buttons.
15. SCANWIDTH (Models 2615A and 2620A). The
SCANWIDTH selectors allow to control the scanwidth
per division of the horizontal axis. The frequency/Div. can
he increased by means of the
► button, and de
creased by
means of the
◄ button. Switching is accom
plished in 1-2-
5 steps from 50 kHz/div. to 50 MHz/div.
The width of the scan range is displayed in MHz/div. and
refers to each horizontal division on the graticule.
The center frequency is indicated by the vertical
graticule line at middle of the horizontal axis. If the
center frequency and the scanwidth setting are correct,
the X axis has a length of 10 divisions. On scanwidth
settings lower than 50 MHz, only a part of the entire
frequency range is displayed.
When SCANWIDTH is set to 50 MHz/div. and if center
frequency is set to 250 MHz, the displayed frequency
range extends to the right by 50 MHz per division,
ending at 500 MHz (250 MHz + (5 x 50 MHz)). The
frequency decreases to the left in a similar way. In this
case the left graticule line corresponds to 0 Hz.
With these settings, a spectral line is visible which is
referred to as
“Zero Frequency” . It is the 1st LO
(oscillator) which becomes visible when its frequency
passes the first IF filter. This occurs when the center
frequency is low relative to the scanwidth range
selected. The “Zero Frequency” is different in level in
every instrument and therefore cannot be used as a
reference level. Spectral lines displayed left of the
“Zero Frequency Point” are so called image
frequencies.
In the
ZERO SCAN mode the spectrum analyzer
operates like a receiver with selectable bandwidth. The
frequency is selected via the
CENTER FREQ. knob.
Spectral line(s) passing the IF filter cause a level
display (selective voltmeter function).
The selected scanwidth/div. settings are indicated by a
number of LEDs above the range setting push buttons.
16. X-POS. (X-position).
17. X-AMPL. (X-amplitude).
IMPORTANT: These controls are only necessary when
calibrating the instrument. They do not require adjustment
under normal operating conditions. A very accurate RF
Generator is necessary if any adjustment of these controls
is required.
18. PHONE (3.5 mm earphone connector). An earphone
or loudspeaker with an impedance >16 Ohms can be
connected to this output. When tuning the spectrum
analyzer to a spectral line possibly available audio
signals can be detected. The signal is provided by an
AM-Demodulator in the IF-section. It demodulates any
available AM-Signal and provides as well one-side FM-
Demodulation. The output is short circuit proof.
19. VOLUME. Volume setting for earphone output.
20. PROBE POWER. The output provides a +5 Vdc
voltage for the operation of an PR-261 near field sniffer
probe. It is only provided for this purpose and requires
a special cable which is shipped along with the PR-261
probe set.