Tait TB9300, Installation And Operation Manual, Page: 83 / 138

TB9300 Installation and Operation Manual
Installation 83
© Tait Limited March 2016
2. Log in to the reciter and select Monitor > Interfaces > RF Interface.
For information on connecting directly to the reciter, refer to
“Connecting a Networked PC to a Base Station” on page 56 .
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 correct helical filter for
the new frequency (as shown in Figure 5.3 ) 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 any order). Each resonator should require
approximately the same amount of adjustment when tuning.
A change in frequency of 5MHz requires approximately one turn of the
tuning slug. If tuning to a lower frequency, adjust the slug in (clock-
wise); for a higher frequency, adjust the slug out (counterclockwise).
7. Change the RF input signal and the reciter’s receive frequency to
0.5MHz above and below the required frequency and check that the
RSSI reading does not drop by more than 0.5dB from the reading at
the required frequency.
8. Recalibrate the RSSI at the new frequency (Calibrate > Reciter >
RSSI).
If you wish to confirm the accuracy of the tuning procedure, carry out a
sensitivity measurement at the new frequency.
1. Included in the TBA0ST2 tool kit. Also available separately as part num-
ber 937-00013-00.