No need to speculate on the 6M K3 NF, we can calculate it. Computing the K3
noise figure from the minimum discernable signal (MDS) gives
preamp off 18 dB (K3/100 test) to 20 dB (K3/10 test)
preamp on 12 dB (Same in both tests)
compare these to other 6M rigs out there:
IC-551D
preamp on 6dB
internal rf amplifier not switchable
DEM 50-28CK transverter with TS-850S IF
preamp on 2.1 dB
FT736R
preamp on 5.7 dB
TS2000
preamp off 20 dB
preamp on 5 dB
IC756 Pro III
preamp off 15 dB
preamp on 5 dB
FT2000
preamp off 26 dB
preamp on 8 dB
So the K3 is pretty deaf on 6M and yes, that is a result of the design emphasis
on HF strong signal handling capability. The Elecraft external preamp with 0.7
dB noise figure and 18 dB gain helps a lot:
K3 with PR6 external preamp
preamp on 0.9 dB
And the preamp is pretty robust to strong signals.
For terrestrial signals in a quiet rural area, a noise figure of 4dB or less is
probably adequate. For EME, you want less. For urban and suburban areas, the
noise is often high and many people, unfortunately won't notice the inadequacy
of the K3's front end on 6M. - Duffey
--
James Duffey KK6MC
DM65tc
Cedar Crest NM
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