Figure 2-2 RX-400A, Rear Panel View
The RX-400A contains separate signal paths for HF and VHF/UHF frequency bands. The
HF section covers the 100kHz to 88 MHz range. The VHF/UHF front-end covers the
range from 88 MHz to 3000 MHz. A single RF input connector is used to cover both
ranges. Internal firmware commands automatically switch between the HF and
VHF/UHF pre-selector sections based on tuned frequency.
During HF operation signals entering the HF converter section first pass through a user
adjustable step attenuator to enhance receiver performance by reducing interference
caused by receive overload in the presence of extremely large signal levels encountered
in the HF frequency domain. The attenuator is followed by multiple pole RF filters (pre-
selector) to eliminate potential interference from out-of-band signals.
For VHF/UHF operation the received signals are routed to the high band pre-selector
which contains switched filter sets to cover sub-octave ranges between 88 and 3000
MHz. For other than U.S. Government, U.S. Military or approved foreign government
use the RX-400A will not provide coverage of the various cellular telephone bands.
The 2 Receiver IF outputs, WBIF 1 and WBIF 2, provide wideband IF signals for use
with auxiliary analysis equipment such as IF pan signal monitors and IF-Tape
converters. The IF center frequency is 21.4 MHz with a bandwidth of 2 MHz below a
tuned frequency of 20 MHz. From a tuned frequency of 20 to 3000 MHz the IF
bandwidth is 6 MHz.
2-2
PN 74446
