The Flex 5000A currently has a noise figure of approx. 16 to 20dB at an MDS
of approx. -126dBm......Addition of a low noise figure preamp (<$100) can
substantially improve the receiver noise figure but is not mandatory for normal
operation. My reference rig is the Icom Pro III which has a 6 meter MDS of
approx. -142dBm with a noise figure of approx. 5 to 8dB.......With an
appropriate preamp the Flex can reach this level of performance with a better
dynamic range to boot......Other brand rigs have the same problem as the Flex
5000A (ex K3 sells a 6M preamp) when it comes to sensitivity and noise
figure.....The preamp is only needed if you wish to do weak signal work......
In general one should consider the total system noise figure of the
station....One of the best performance improvements can be had by reducing the
feedline losses.....Losses in the receiver front end directly reduce the
receiver noise figure and feedline affects both TX and RX performance.....There
are many other metrics one should consider in rig performance....I own several
of the top-end rigs and have found the Flex 5000A beats them hands down in
overall receiver performance....The receiver dynamic range (weakest to
strongest signal) for the Flex is phenominal......The receiver noise reduction
along with the filtering is additionally on par with > $10K rigs.........
In the words of an old timer.....spend all your money on the antenna and
feedline ....if you have any money left over buy a rig......
73s WA4CAX.......
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