Electro-Metrics EM-2115, Instruction Manual

Page: 81 / 278

EM-2115 4.0 SERVICE, MAINTENANCE, CALIBRATION
(EM2115S4-13)
f. The Digital Voltmeter monitoring the voltage on A8-16 should indicate +1.50
VDC ±0.05 VDC. If not, adjust A4A1-R51.
g. Decrease the signal input level by 60 dB to +38 dB(µV), the voltmeter should in-
0.115 VDC ±0.05 VDC. If not, adjust A4A1-R45.
h. Step the signal input level in 10 dB steps from +98 dB(µV) to +38 dB(µV) (7
steps), the digital voltmeter should indicate the DC output voltages noted in Table
4.1. If not, repeat Steps f and g.
i. Starting at the +98 dB(µV) reference level, check the 20 dB overload limit for the
log channel. Increase the input signal level in two 10 dB steps, +108 dB(µV) and
+118 dB(µV) respectively. The voltmeter should indicate the DC output voltages
noted in Table 4.1. At the end of this step remove the external input and reconnect
the subminature coaxial cable to A4J4.
NOTE: The specification limit allows a 2 dB compression for the 20
dB increase in signal level, e.i. 18 dB increase in front panel
meter indication for a 20 dB signal level increase. The voltme-
ter monitoring the voltage on A8-16 would indicate the follow-
ing for 1 dB and 2 dB compression of the DC output voltage
for the last incremental step:
19 dB for 20 dB: +1.937 VDC
18 dB for 20 dB: +1.914 VDC
j. Switch the Frequency Range to 2.4-5.5 MHz. Repeat Steps e thru i, except for the
following:
1) Remove the subminiature coaxial cable from A4J2.
2) Set the Bandwidth to 100/120 kHz.
3) Connect the Signal Generator setup to A4J2 and apply a 1.6 MHz cw signal at
an input level of +97 dB(µV). Refer to Table 4.1 for the signal input levels.
4) At the end of this step remove the external input and reconnect the subminature
coaxial cable to A4J2.
Table 4.1
Log Detector Signal Input Level Vs Dc Output Voltage