Tektronix 2714 User Manual page 145

Enhanced Versatility
[A], [B], [C], and [D] are toggle-action keys that activate and deacti-
vate the display registers. A register's contents are displayed only
when it is active (red LED lit), although it still contains saved data as
long as its green LED is lit.
Turn on the C register by pressing [C].
The only change that might be apparent is an increase in intensity
since the 2714 is now displaying the C trace on top of the D trace.
Now turn on the A and B registers by pressing [A] and [B].
There may be an increase in intensity, but the shape of the spectral
display should not change, because each register contains exactly the
same information. Deactivate the B, C, and D registers by pressing
[B], [C], and [D].
This display is no different than the D register waveform. Verify this by
turning on the D register and turning off A (press [D] and then [A]).
Verify that this is true of the other registers by alternately switching a
new one on and the previous one off.
Analog Display — Deactivate all registers to display the analog
output of the 2714. Note its similarity to the MAX/MIN display. Any time
all four red LEDs are extinguished, the analog output of the 2714's
detector is displayed. The digitizer is still working; you have just
disabled all the display registers. The analog display can be very
useful for viewing time-varying modulation such as television video
. signals. It is also useful if you are used to a spectrum analyzer that
may not have digital display capabilities; since it provides a display
you are familiar with and allows you to see the similarity between the
MAX/MIN display and the analog signal. You can usually obtain a
crisper analog display, especially at higher sweep speeds, by varying
the intensity (see INTENSITY at the end of this section) and/or turning
register.