Stanford Research Systems SR830, Manual

Page: 61 / 177

4-8
Front Panel
The actual dynamic reserves (in dB) for each sensitivity are listed below.
Sensitivity Low Noise Normal High Reserve
1 V 0 0 0
500 mV 6 6 6
200 mV 4 14 14
100 mV 0 10 20
50 mV 6 16 26
20 mV 4 24 34
10 mV 0 20 40
5 mV 6 26 46
2 mV 4 34 54
1 mV 10 40 60
500 µV 16 46 66
200 µV 24 54 74
100 µV 30 60 80
50 µV 36 66 86
20 µV 44 74 94
10 µV 50 80 100
5 µV 56 86 106
2 µV 64 94 114
1 µV 70 100 120
500 nV 76 106 126
200 nV 84 114 134
100 nV 90 120 140
50 nV 96 126 146
20 nV 104 134 154
10 nV 110 140 160
5 nV 116 146 166
2 nV 124 154 174
Do not use ultra high dynamic reserves above 120 dB unless absolutely
necessary. It will be very likely that the noise floor of any interfering
signal will obscure the signal at the reference and make detection difficult
if not impossible. See the SR830 Basics section for more information.
Auto Reserve
Pressing [AUTO RESERVE] will change the reserve mode to the mini-
mum reserve required. Auto Reserve will not work if there are low fre-
quency noise sources which overload infrequently.
[Time Constant Up/Dn]
This key selects the time constant. The time constant may be set from 10
µs to 30 s (detection freq.>200 Hz) or 30 ks (detection freq. <200 Hz).
The detection frequency is the reference frequency times the harmonic
detect number. The time constant is indicated by 1 or 3 times 1, 10 or
100 with the appropriate units.
The maximum time constant is 30 s if the detection frequency is above
200 Hz and 30 ks if the detection frequency is below 200 Hz. The actual
range switches at 203.12 Hz when the frequency is increasing and at
199.21 Hz when the frequency is decreasing. The time constant may not
be adjusted beyond the maximum for the present detection frequency. If
the detection frequency is below 200 Hz and 100 s is the time constant