Manual - 8500A Series Peak Power Meter - Giga-tronics

Series 8500A Peak Power Meters
3. Verify that the Cursor Delay setting is adequate for both channels by switching to the other
channel. Use the same Start, Window, and Cursor Delays as in the first channel. If the pulses
occurred at the same time, the Cursor would be close to the center of the pulse sampled by the
other channel (see Figure 2-13).
GOOD
BAD
Figure 2-13. Typical Good & Bad Cursor Delay Settings
4. Switch channels, checking to be sure that the Cursor is not placed close to the edge of either of
the pulses being sampled.
5. Once the Cursor has been satisfactorily set, to activate the Ratio Display Mode press [MENU]
(7) [F2].
The default setting for the type of signal being used by both channels is Peak. This is verified by PK/PK
being displayed in the lower right hand corner of the readout. If this is not the case, select Peak operation
by pressing [A] [F1] [B] [F1].
The PPM should now be displaying the ratio of the two pulses (similar to Figure 2-12). Be sure to use
the FREQ key and Offset function if necessary.
Ratio’ing Peak to CW Signals
This function is very useful in many applications such as traveling wave tube (TWT) testing that require
the measurement of gain under pulsed conditions. This could be a problem when the TWT has a CW
input and a pulsed output. The PPM easily performs this type of measurement using the following
procedure:
1. Make a single channel Peak measurement at the port of the device under test that has the pulsed
signal.
2. Set the Cursor at the desired point on the displayed pulse profile. Using the Graph Mode is the
simplest way to do this.
3. Select the Ratio Mode by pressing [MENU] (7) [F2].
4. Set which channel will be CW by pressing [B] [F2] (if channel B is to be CW) or [A] [F2], (if
channel A is to be CW).
5. Set which channel is to be Peak by following the same procedure as above, only press [F1]
instead of [F2].
The lower right hand corner of the readout will indicate which channel is CW and which is
PEAK. Whichever indication is farthest to the right side will be channel B.
2-36 Manual No. 20790, Rev C, November 1998
Superceded by Revision D, March 2009