Introduction - SpectraDynamics HPDA-15RMi-S Operating Manual

1.0 Introduction

The HPDA-15RMi-S is a high performance frequency distribution amplifier with an auto
switch function that allows the selection of the RF input to be distributed. The selected
RF input supplies 10 buffered unity gain outputs. The instrument has a manual mode and
autoswitch mode of operation. In manual mode, the RF input can be selected with a
toggle switch on the front panel, or by sending a command through the Ethernet
interface. In autoswitch mode the two RF input levels are monitored and compared to a
set threshold of +7 dBm. Upon failure of a selected input channel the amplifier switches
over to the alternate RF input with a switching time less than 1 us.
The selected RF input is buffered and distributed to ten unity gain outputs. The typical
cross-channel isolation of the RF distribution module is 130 dB and reverse isolation is
typically greater than 140 dB. The phase noise of the modules is exceptionally low,
typically –147 dBc/Hz @ Fourier frequency of 1 Hz and –170 dBc/Hz @ Fourier
frequencies greater than 10 kHz. Both the input and output are matched to 50 ohms to
obtain better than 25 dB return loss. All outputs are AC coupled and the grounds are DC
isolated to reduce the effect of ground loops.
The HPDA-15RMi-S is designed to be powered by a 100 to 240 VAC mains source or by
a +12 to +36 VDC power source. The DC power supply may be used as a main power
source for the instrument or in conjunction with the AC power supply as a backup in case
of loss of the main AC power. The instrument is designed to automatically switch from
AC to DC supply operation using a Schottky diode network and charge storage
capacitors to avoid any glitches and ensure uninterrupted continuous operation.
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