TB9400/TN9275 Installation and Operation Installation 69
© Tait International Limited May 2023
To check the RSSI level and tune the receiver front end (if required), follow
these steps.
1. Remove the reciter from the subrack and reconnect the system
control bus cable to power up the reciter.
2. Log in to the reciter and select Monitor > Interfaces > RF Interface.
For information on connecting directly to the reciter, refer to “Local
Connection to a Base Station” on page 93.
3. Feed a signal at the currently tuned receive frequency and at a level
of –80dBm into the reciter’s RF input. Check that the RSSI reading
on the RF Interface page is –80dBm ±1dB. Note this reading.
4. Set the reciter to the new receive frequency.
5. Change the RF input signal to the new receive frequency at
–80dBm. Check that the RSSI reading is –80dBm ±1dB. If it is, the
receiver front end does not require tuning. If it is not, go to the next
step.
6. Using the Johanson tuning tool
1
, adjust the helical filter for the new
frequency (as shown in Figure 4.3) to obtain a peak RSSI reading.
This reading should be within 1dB of the reading at the previous
frequency.
Adjust the center resonator of the filter first, followed by the two
outer resonators (in either order). Each resonator should require
approximately the same amount of adjustment when tuning.
Figure 4.3 Identifying the H band receiver front end helical filter
1. Included in the TBA0ST2 tool kit. Also available separately as part
number 937-00013-00.
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