Canberra 2015A, User Manual

Page: 23 / 56

signal, on channel 1 of the oscilloscope, exceeds the LOWER LEVEL (E)
plus the WINDOW (
∆
E) discriminators, a positive logic pulse will appear.
Change the DISC A jumper plug back to the LLD position.
12. Change the DISC B jumper plug to the IN position and the LLD jumper plug
to the EXT position. The LOWER LEVEL (E) discriminator function will no
longer be controlled by the front panel LOWER LEVEL (E) control. The
function will now be controlled by an external voltage of 0 to + 10 volts at
the rear panel DISC BNC. Change the DISC B jumper plug back to the OUT
position and the LLD jumper plug to the INT position.
Reference Data on Cables
Figures 14 and 15 show a typical output pulse at the load end of the designated RG-58
cable, and the same point using RG-62 cable. In each case Figures 14 and 15 show
high impedance (1 k
Ω
) and 50
Ω
termination conditions. Clearly the fastest, cleanest
pulse is realized with the RG-58 cable. With the source match provided, loading ef-
fects are limited to amplitude changes only. RG-58 cable is therefore recommended
for best compatibility with the DISC and SCA OUTPUTS.
RG-58 cable: R
source
= 50 ohms
Upper Trace: R
load
= 1k ohms
Lower Trace: R
load
= 50 ohms
Scope:
Horizontal = 0.1
µ
s/cm
17
Reference Data on Cables