NARDA PMM 9010 Series, User Manual

Page: 151 / 284

PMM 9030/9060/9180 Frequency Extension 11-39
11.15.4 Level 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 +55 dB
μ
V to 90 dB
μ
V (-50 to - 15 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 9030/9060/9180 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.
11.15.4.1 Input:
Attenuators
and
preamplifier
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) up to the max attenuation
available of 55 dB.
Depressing either one of these keys force the receiver in manual
attenuation.
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 10 dB.
The internal 10 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 10 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 9030/9060/9180 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 dB
μ
V).
Before to apply an unknown signal to PMM 9030/9060/9180 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.