AD604
Rev. E | Page 25 of 32
Connecting the DSX Inputs to the Preamplifiers
To connect the DSX inputs to the preamplifiers, install jumpers
in the JP6 lower position and in JP15. Verify that the jumpers in
JP13 and JP14 are removed.
Cascaded DSX
To channel-cascade the two channels, insert a jumper in JP13.
The resulting single-channel gain range is 96 dB. Verify that
JP14 and JP15 are removed.
The gains of cascaded VGAs can be controlled independently
or in common. For common control, insert a jumper in the top
position of JP4. To use the trimmer as a gain control, insert a
jumper in JP1. For external control, remove JP1 and connect a
signal source at VGN1 or VGN2 test loop.
PREAMPLIFIER GAIN
Jumpers in JP7 and JP12 select between two preamplifier gains:
14 dB and 20 dB. Intermediate gains are derived by installing
resistors in the R11 and R12 positions. The 14 dB and 20 dB
preset gains are accurate due to close matching of thin film
resistors. The gain accuracy after installing external resistors is
subject to inherent tolerance of absolute accuracy.
OUTPUTS
The DSX outputs are available on OUT1 and OUT2 SMA
connectors and are series terminated with decoupling capacitors
and 49.9 Ω series resistors. These components can be replaced
to accommodate other output impedances.
DC OPERATING CONDITIONS
Table 4 lists the trimmers and their functions provided for
convenient dc level adjustments of gain, reference voltage,
and output common-mode voltage. Table 5 lists the jumpers
and their functions.
Table 4. Trimmer Functions
Trimmer Function
R1
Gain of Channel 1
R2
Reference voltage adjustment
R3
Output common-mode voltage adjustment
R4
Channel 2 gain adjustment
Table 5. Jumpers
Jumper No.
Function
1
Connects R1 gain adjust wiper to VGN1.
2
Connects R2 reference voltage trimmer to VREF input.
3
Connects common-mode voltage trimmer to VOCM.
4
Connects VGN2 to R4 Channel 2 gain trimmer or to VGN1 or common gain adjustment.
5
Connects –DSX1 to CH1 VGA IN (−) or to ground.
6
CoDSX1 (ac-coupled) to preamplifier output of Channel 1 or to the CH 1 VGA IN (+) SMA connector.
7
When open, the Preamp 1 gain is 20 dB; Preamp 1 gain is 14 dB when a shunt is installed.
8
Shunt in left position disables Preamp 1; shunt in rightmost position enables Preamp 1.
9
Shunt in left position disables Preamp 2; shunt in rightmost position enables Preamp 2.
12
When open, the Preamp 2 gain is 20 dB; Preamp 2 gain is 14 dB when a shunt is installed.
13
Cascades DSX2 with DSX 1 when a jumper is inserted.
14
CoDSX2 (ac-coupled) to preamplifier output of Channel 2 or to the CH 2 VGA IN (+) SMA connector.
15
CoDSX2 (ac-coupled) to preamplifier output of Channel 2.
16
Connects –DSX2 to CH2 VGA IN (−) or to ground.
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