Input And Midstage Pads; Flatness Control - Motorola BLE Series Installation And Operation Manual

3 3 3 3 - - - - 6 6 6 6 A m p l i f i e r S e t u p
The information in Table 3-2 is shown as a graph in Figure 3-2:
F i g u r e 3 - 2
F r e q u e n c y v e r s u s c a b l e s l o p e
0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
-11
-12

Input and Midstage Pads

Install Model JXP-*T pads to attenuate the signal per system design drawings. Generally, this
consists of attenuating excessive input levels. You should pad the input to achieve unity gain.
Select and install the specified pad in the socket labeled
midstage pad ( - ) normally remains at 0 dB but can be used to adjust the gain level and
JXP MID
achieve the gain specification. Refer to Section 6, "Operating Tips," for midstage padding
information and recommendations.

Flatness Control

The *LDR/*/II circuit board includes flatness controls and a fixed cable equalizer for 750 MHz or
870 MHz. This equalizer, plus the contribution of the hybrid gain stages, produces
approximately the dB of slope indicated by the model number (8 dB of tilt with an *LDR/8/II).
The *LDR/*/II variable resistors and capacitors can be adjusted to flatten the response from
marker 1 to marker 4 as illustrated in Figure 3-4. Use C1, C2, R1, and R2 on the LDR board
shown in Figure 3-3 for low-end flatness response (marker 1 to marker 2). The low-end flatness
controls compensate for the roll-off caused by the diplex filters. Adjust C3 and R3 for a flat
response around 400 MHz (between marker 2 and 3). Adjust C7, C8, and R8 for a flat response
across the band (marker 1 to marker 4). Adjust C6 for maximum gain at the high end (marker 3
to marker 4).
!
C1 produces a peak that is centered just below the lowest forward frequency and varied in
amplitude by R1.
!
C2 produces a peak that is centered at approximately 100 MHz and varied in amplitude by
R2.
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
Frequency (MHz)
-
JXP IN
on the chassis cover. The
SCS-1
SCS-2
SCS-3
SCS-4
SCS-5
SCS-6
SCS-7
SCS-8
SCS-9
SCS-10