Thermal Drive Unit - Motorola BLE Series Installation And Operation Manual

3 3 3 3 - - - - 1 0 1 0 1 0 1 0 A m p l i f i e r S e t u p
If you use an SCS cable simulator and the design value is changed, you must also adjust the
input pad. For each 1 dB increase in SCS value, 1 dB of loss is introduced at 750 MHz or
1.1 dB of loss at 870 MHz. Therefore, to maintain a proper gain level, it is necessary to
adjust the input pad value as follows:
!
For each increase in SCS value, decrease the input pad by 1 dB for the BLE75* or 1.1 dB
for BLE87*. Pads are available in 0.5 dB increments, therefore, use to closest value
possible.
!
For each decrease in SCS value, increase the input pad by 1 dB for the BLE75* or 1.1 dB
for BLE87*.
!
If you replace an SFE with an SCS, reduce the value of the input pad by the value of the
SCS for the BLE75* or a good estimate for the BLE87*. Use the 1 dB loss at 750 MHz to
1.1 dB loss at 870 MHz ratio to be exact.
8
Measure the output level at the highest frequency. It should be within 1 dB of the system
design level. If it is not, change the input pad (JXP IN) to a higher or lower value to achieve
the proper level. The midstage pad (JXP MID) normally remains at 0 dB, but can be used to
adjust the gain level and achieve the gain specification. Refer to Section 6, "Operating Tips,"
for midstage padding information and recommendations.
T h e rma l D r ive Un i t
The TDU senses temperature and controls the Bode board. It is assumed that the cable is
subjected to the same or similar temperature, therefore, the TDU should not be used for
underground installations.
To set-up the TDU:
1
Place the jumper on the TDU (Figure 3-5) to the
the amount of cable for which the TDU compensates at the highest frequency preceding the
BLE*/* station. Low = 0 dB to 15 dB of cable, medium = 15 dB to 30 dB, and high = 30 dB or
more of cable.
F i g u r e 3 - 5
T D U c a b l e s e l e c t o r
2
Position the drive control select jumper (Figure 2-9) temporarily in the
perform the complete procedure described in Manual Gain Control if not already completed.
3
Position the drive control select jumper to
B L E * / * I n s t a l l a t i o n a n d O p e r a t i o n M a n u a l
,
LOW MEDIUM
Thermal
Medium level
Low High
.
AUTO
, or position to specify
HIGH
position and
MAN