Tait T860 Series II, Service Manual

Page: 62 / 264

B4.6 T865 Functional Testing
M860-00-Preliminary
30/06/98 Copyright TEL
4.7 Noise Mute (If Linked In)
Rotate RV230 (front panel gating sensitivity) fully anticlockwise.
Apply an on-channel signal from the RF generator at a level of -110dBm with
3kHz deviation (2.4kHz) [1.5kHz] at 1kHz.
Increase the RF level in 1dB steps, checking that the mute opens for an RF input
level of approximately -105dBm.
Turn the RF off and check that the mute closes.
Rotate RV230 clockwise and check that the mute opens.
Reset RV230 to give the required opening sinad.
Note: False opening of the mute can occur if the RF generator’s attenuator is noisy
when the level is being changed.
4.8 RSSI
Apply an on-channel signal from the RF generator at a level of -100dBm with
3kHz deviation (2.4kHz) [1.5kHz] at 1kHz.
Using a high impedance DMM, check that the RSSI output voltage on pin 5 of
D-range 1 (PL100) is 4.5V (nominal).
Vary the RF level in 5dB steps and check that the RSSI output voltage changes at a
rate of approximately 15dB/V over the range of -115dBm to -70dBm (refer to Fig-
ure 4.2 for RSSI voltage vs signal strength).
Figure 4.2 T865 RSSI Voltage vs Signal Strength
RF Level (dBm)
-130 -120 -110 -100 -90 -80 -70 -60
1
2
3
4
5
6
7
8
RSSI V
oltage