Tektronix TPA-N-PRE Instructions Manual

TPA-N-PRE
Preamplifier
for the MDO4000 Series
Instructions
1
*P071305800*
071-3058-00

Overview

This external RF preamplifier accessory for the
MDO4000 Series Mixed Domain oscilloscopes
improves the MDO's ability to investigate
low-amplitude signals by providing 12 dB of
gain and lowering the noise floor (DANL)
by 10 dB. The TPA-N-PRE works with all
MDO4000 models.

Connecting to the MDO4000

To install, simply plug the N-connector side into
the MDO4000 front-panel RF connector. Turn
the thumb-wheel until the connection between
the MDO4000 and the TPA-N-PRE is rigid. The
preamp cannot be over-tightened by hand. If the
connection is not rigid, the unit may not perform
properly.
Upon attachment, if the MDO4000 does not
recognize the preamp from a previous attachment,
it will upload the calibration constants (preamp
gain vs. frequency) stored on the preamp and
store them in non-volatile memory. This will
take less than seven seconds and only occur
the first time a preamp is used with a particular
MDO. If the MDO does recognize the preamp, it
will use the calibration constants that it already
has stored on board. The MDO will include the
preamp gain in its correction factors providing a
complete, calibrated RF system.
The preamp has two states. These are "Amplify"
and "Bypass". In the Amplify state, the preamp
amplifies the input signal. In the Bypass state,
the preamp passes the signal through without
amplifying it. The state of the preamp is not set
directly, but is determined by the preamp mode
and the RF Reference Level settings input by
the user. In "Auto" mode, the preamp will be
in the Amplify state when the Reference Level
is ≤ –30 dBm and in the Bypass state when the
Reference Level is > –30 dBm. In the Bypass
mode, the preamp will be in the Bypass state no
matter where the Reference Level is set. The
LED on the preamp indicates the preamp state.
It will show green for amplify, amber/orange for
bypass or red in the case of an error.
The preamp menu can be accessed by pressing
the button on the preamp, or through the RF >
More > Probe Setup menu. In this menu, the
preamp state is displayed, and the preamp mode
can be changed by the user.