Table of Contents
Advertisement
4.2.2 Level
4.2.2.1 Input:
Attenuators and
preamplifier
The Level function has 5 sub-menus, each one with several options..
Pressing the Display button it is possible to set two parameters: the
visualized Dynamic range (chosen between 80, 100 and 120dB) and the
Reference Level, that can be increased or reduced by steps of 5dB within
the range +80 dBµV to 135 dBµV (-25 to +30 dBm).
The Input button opens a submenu which is dedicated to the setting of the
input attenuator and to switch on-off the built-in preamplifier.
The PMM 9010 receiver takes automatically into account the settings of all
the Input parameters and always displays the correct value of the level. The
User is not required to make any correction to the readings.
Being entered in the Input submenu, to increase or decrease the attenuation
at the input, press Att + or Att -, and for each touch the attenuation is
increased or decreased of 5 dB (preset value). Depressing either one of
these keys force the receiver in manual attenuation.
When the input attenuation is 0dB (condition that can be achieved only if the
Minimum Attenuation is set to 0 dB as well), the yellow led to the left of the
input BNC connector is ON and indicates a warning status.
The Min Att button acts as a toggle switch: it selects or deselects the
minimum attenuation of 10 dB. When the minimum attenuation is selected,
the attenuator – doesn't matter if in automatic or in manual condition -
cannot be lowered under 10 dB.
Unless specifically required by the test conditions, do not remove the
minimum attenuation of 10 dB.
With the Preamp key it is possible to insert or exclude the built-in low noise
preamplification of 20 dB.
The internal 20 dB preamplifier can be used when very weak signals have to
be investigated. As already mentioned, with the preamplifier ON the receiver
takes automatically care of the 20 dB gain when measuring the signals.
The Att Auto button is used to switch from the two conditions of manual or
automatic attenuation setting.
Please note that the switching of the attenuators is relatively noisy and you
can perceive it distinctly with a "click" for each switch operation.
Using 0 dB attenuation PMM 9010 has no input protection.
This is a potentially dangerous condition for the input stage of the
receiver.
Use 0 dB attenuation only if you are very sure that your input signal is
less than 1 V (or 120 dBµV).
Before to apply an unknown signal to PMM 9010 receiver, use an
oscilloscope or a wide band RF voltmeter to measure it. In any case set
Min. ATT at 10 dB and select the maximum available attenuation with
preamplifier OFF.
If needed, add an external coaxial attenuator on the input signal line.
Sweep Mode Operating Instructions
4-3
Advertisement
Table of Contents
