First Measurements - Hameg Instruments HM5510 Manual

F i r s t m e a s u r e m e n t s
Further precautions:
1. If the signals are unknown it is advisable to fi rst measure
their amplitudes e.g. with a scope before applying them to the
analyzer. (Use a 50 ohm termination with the scope.) Also start
always using –40 dB attenuation and then switch to higher
sensitivity if necessary.
2. Remember that signals may contain excessive amplitudes
outside the range of the analyzer, i.e. 150 kHz to 1050 MHz.
These would not be displayed, will overdrive and possibly
destruct the mixer.
3. The range from 0 to 150 kHz is not specifi ed, thus the dis-
play of signals in this range does not mean that such display
is useful.
4. A "zero peak" signbal will be always visible if the 1
oscillator passes through the 1
differs due to tolerances, even if it reaches full screen size this
does not constitute a fault of the instrument.
If the base line (noise band) at the bottom of the
display shifts upward upon feeding in a signal this
will indicate the display of spectra with excessive
amplitudes. In such cases attenuate the input
signal.
Intensity, Focus
Do not increase the intensity level too much as this will not
improve the visibility of signals but to the contrary the focus
will be adversely affected. Too much intensity will also cause
the phosphor to suffer in the area where the noise band nor-
mally is located.
34
Subject to change without notice
st
local
st
IF fi lter. The level of this peak

First measurements

Settings
Prior to connecting any signal make sure that any DC content
is max. ±25 V and that the HF level is +10 dBm.
Attenuator
Set the attenuator fi rst to maximum = 40 dB, the "40 dB-LED"
will light.
Frequency adjustment
Set the CENTER FREQ to 500 MHz (C500.000 MHz) and the
SPAN to 1000 MHz (S1GHz).
RBW (Resolution bandwidth)
First use the 500 kHz fi lter and turn the video fi lter (VBW) off.
Is there only the baseline noise band increase the sensitivity
i.e. decrease attenuation.
If the baseline should shift upward this may indicate high signal
amplitudes outside the instrument's useful band. Do not pay
attention to the zero peak, the setting of the attenuator depends
on the highest amplitude input signal. Optimum setting is given
if the highest spectral line reaches to the top of the display
(which is the reference line) but does not exceed it, otherwise
the attenuation has to be increased. If the internal attenuator
is already at –40 dB use an external one in addition. With high
levels it may be wise to check its power rating.
Full span (S1GHz) measurements are in general only useful
for a coarse overview. Decreasing the span will require to fi rst
change the center frequency (CENTER FREQ) so as to move the
signal into the display center, then change the span.
If necessary the RBW can now be decreased to 20 kHz and
the video fi lter inserted. The UNCAL warning in place of REF-
LEVEL or MARKER LEVEL would indicate that the amplitudes
shown may not be correct. The span may be too high or the
RBW too low.
Measurements
The marker is used to derive numbers. Set the MARKER (
MRKER LED should light up) to the signal part of interest by
turning the knob. Read the frequency (Mxxx.xxx MHz) and
the level (Lxx.xdBm) on the LCD display. The level reading
automatically takes the reference level (REF.-LEVEL) and the
input attenuation (ATTN) into account.
Without using the marker the level can be read from the dis-
play: the top graticule line is the reference level (R....dBm).