ESCO Technologies ETS Lindgren 3301B, Руководство пользователя

Страница: 20 / 56

20 | Principles of Operation
S
ATURATION
I
NDICATOR
The Saturation indicator is located above the power indicator. Readings should
not be taken when the unit indicates it is in saturation. If this occurs, input to the
unit should be reduced by placing the unit in the low gain mode or by switching in
internal attenuation. Impulsive type signals present a particular problem in that
they may put the unit into a non-linear region without triggering the saturation
circuit. When dealing with impulsive type signals, the 63 dBu V/m/MHz should be
strictly observed. If a signal exceeds this limit, the internal attenuation should be
applied. The limiting factor on handing impulsive signals is the unit output
capability. Therefore, once the internal attenuators are engaged, most higher
impulsive signals may be measured. For example, with the 30 dB attenuator
engaged, a 93 dBuV/m/MHz may be measured.
B
ATTERY
C
HARGING
P
ORT
A Battery Charging port is provided for easy recharging of the sealed lead-acid
batteries internal to the unit. To charge the unit, turn off the power switch and
plug in the battery charger. The charging circuit will not charge the batteries
when the unit is on.
6.3 Internal Options
Internal to the unit is a 4-switch bank of slide switches. These switches control
the internal attenuation and the low frequency roll off.
To access the switch bank, hold the unit upside down and remove the bottom
cover. With the unit upside down and the front panel to the left:
•
The top switch, closest to the fuse holder, adds 10 dB of internal
attenuation.
•
The next switch down adds 30 dB of attenuation.
•
The third switch sets the low frequency roll off of 3 dB down at 1.9 kHz.
•
The fourth switch sets the low frequency roll off of 3 dB down at
22 kHz.