[Elecraft] K3 6m pre-amp

[K3KO]

Dave,

If I do the conversion to microvolts, it indicates 0.8 microvolts for no
preamp and 0.04 microvolts for a preamp (I think the column headings are
reversed)  I believe MDS is a 3db s/n ratio.

For comparison.

My IC706IIG has the following 50MHz specs 0.12 microvolts for 10 db s/n
ratio.  Filter unspecificed, mode SSB/CW, preamp on.  My guess it is the
stock (2.7KHz?) filter   What it really measures, I don't know.
I know why they didn't use the narrower available CW filters for the ICOM
specs.  The 300Hz filter has a lot of uncompensated for loss.  So much so I
can't use it on 6M CW for any weak signal work.

All that aside.  Trying to put the two on an equal footing.  Say 400Hz, 3db
S/N indicates the 706 would come in at about (preamp on, 400Hz lossless
filter, 3db S/N) yields -131 dbm (if I did the math right)

One thing for sure, one can't compare S-meter readings from rig to rig.  It
has to be some kind of measurement with attenuators or lab equipment- - like
you did with the lab generator.

What are the 480 specs on 6M?

I do disagree with a CW op not being able to copy a signal with a 3db s/n
ratio.  In fact, decent operators can copy CW signals several db below the
noise.  

73 de Brian/K3KO
------------------------------------------------------------------------------
Hallo,

> I can't see any comment made by the BCC re the 6m sensitivity, only
> Wayne's response.


I am working on the translation of a much delayed update of the BCC report.
In the mean time we have done MDS measurements for various bands:

-----------------------------------------
Band    w Preamp        w/o Preamp
160m    -129dBm         -137dBm
80m     -133dBm         -138dBm
40m     -133dBm         -138dBm
20m     -134dBm         -138dBm
15m     -132dBm         -137dBm
10m     -130dBm         -137dBm
6m      -129dBm         -134dBm

Table 2: MDS of the K3 at 400Hz
-----------------------------------------

vy 73 de toby
-- 
DD5FZ (ex 4n6fz, dj7mgq, dg5mgq, dd5fz) 


Dave G4AON wrote:
> 
> I've just done an A/B comparison between my K3 and my Kenwood TS-480SAT. 
> I had the pre-amp switched on in both transceivers.  On the 480 I was 
> able to comfortably hear a signal from my signal generator some 10 dB 
> lower in level on the 480 than I could on the K3, which is quite a 
> difference.
> 
> I think the often quoted MDS (minimum discernible signal) makes the 
> specification appear "better" than it really is and is not realistic. 
> MDS is a measure of the signal that increases the output of the receiver 
> by 3 dB when the signal generators output is turned on. You couldn't 
> copy by ear a signal of that level except for the slowest of Morse 
> keying and then it would be very hard going. The "old fashioned" signal 
> level that gives a signal to noise ratio of 10 dB is more meaningful, as 
> a 10 dB above the noise signal is a comfortable listening level that we 
> can all equate to.
> 
> I had done earlier A/B comparisons between the K3 and 480 where I didn't 
> think there was a difference, I must have mistakenly not use the 480 
> pre-amp...
> 
> 73 Dave, G4AON
> K3/100 #80
> 
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