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3.3 AC gain
5. Connect the BNC Tee adaptor to the other end of the cable, and
connect the 50 Ω terminator to the Tee. Connect the male end of
the Tee to the banana‑to‑BNC adaptor
6. Plug the banana‑to‑BNC adaptor into the digital voltmeter, and
note the DC volts on a scale showing at least 100 μV resolution.
Since the gain is + 40 dB, the actual offset reference to input will be
this reading divided by 100. Record this offset r.t.i. as the + Out
offset.
7. Move the BNC cable from the + Out connector to the − Out
connector on the SR446, and repeat the measurement. Record
this offset r.t.i. as the − Out offset.
Gain accuracy is measured at 1 MHz, for each output, and at three gain
setting of the SR446. For specified accuracy, coupling should be DC and
input impedance 50 Ω .
To configure the SR865A to verify the amplifier AC gain accuracy:
1. Both the SR865A and the SR446 should be powered on and
warmed up.
2. Connect a 50 Ω terminator to the BNC tee, and connect the tee to
the "A" input of the SR865A.
3. Reset the SR865A by pressing the [Save Recall] button. Then touch
the [Recall default] tile at the upper‑left of the screen, and touch
[Confirm].
4. Press the [Config] button, and then touch the on/off tiles to disable
graphs for X, Y, and Θ . Leave "Data 3" set to R, and graph On.
Touch [close].
5. Press the [Screen Layout] button twice, so the display is showing
large numeric displays for X, Y, R, and Θ , and the bottom half of
the display has a strip chart for R.
6. Push the INPUT RANGE down button twice, to select 100 mV.
7. Push the FILTER [Slope] button three times, to select 24 dB. Then
press and hold the [Slope] button to select Advanced.
8. Near the top left of the display, touch the gray Fint tile to bring up
the control window for setting internal frequency. Enter 1 MHz.
9. Near the top right of the display, touch the gray Ampl tile to set
the sine out amplitude. Enter 2 mV.
SR446 400 MHz Programmable Gain Preamplifier
3 Performance Verification
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