FLEX-6000 Signature Series - SmartSDR for Windows Software User’s Guide
Page 145
Copyright 2018 FlexRadio Systems. All Rights Reserved.
The preamplifier has protection circuitry to prevent damage above levels of +10dBm. This protection
circuitry will cause distortion in received signals if the level exceeds +10dBm. For this reason, pre-
amplification should not be used when the input signal level will meet or exceed +10dBm. When
performing all testing of a full duplex configuration, it is highly recommended that the preamplifier
be disengaged until it can be determined that the power level from the transmitter will not reach
+10dBm in any operating scenario.
34.4.3 High-Performance Analog to Digital Converter Block (ADC)
The ADC block, or digitizer, converts the received signals into digital data. All ADCs have overload
points and damage points, but there is some variability in overload symptoms. With the FLEX-6000
Signature Series radios, the ADC overload point varies from +7dBm (FLEX-6300) to +9dBm (FLEX-6500
and FLEX-6700). This overload point is a “soft overload” meaning that at this point the receiver will
begin to show a performance drop. The ADC generally functions better with increasing signal levels
up to this point. At the soft overload point, the receiver will begin to develop spurs that will appear
in the panadapter and these spurs will grow as power is increased. A digital overload point will be
reached around +12dBm (level varies by receiver) at which point the receiver will cease to function
normally, producing substantial distortion in received signals and rendering reception difficult.
At levels above +15dBm (level varies by receiver), the ADC can be damaged so the FLEX-6000 contains
circuitry to disengage the ADC from the antenna. While circuitry should protect the radio from a
damaging signal, it is highly recommended that station configuration be designed such that signal
levels above the soft overload point are prevented from entering the antenna connector of the radio.
FlexRadio Systems assumes no responsibility for damage incurred from high signal levels entering
the receiver.
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