[Elecraft] K3 - Performance on 6M?

[Bill K9YEQ]

how do you calculate... I want to work more 6m signals and need to know the
testing method. If signals are that better then I need to add the external
unit.

Bill
K9YEQ

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of James Duffey
Sent: Friday, April 02, 2010 4:54 PM
To: elecraft at mailman.qth.net
Cc: James Duffey
Subject: Re: [Elecraft] K3 - Performance on 6M?

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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