K-3 Noisy Receiver?

[RLVZ]

Interesting data but what am I missing here?  "Note the K3 audio  amplifier
is the cleanest hands down".  Looking at the data below, doesn't  it show
that in the 22 audio ranges from 50-3200hz that the MP has a  lower noise
level in 12 out of 20 ranges and is about identical in  most of the others?  
Doesn't a lower negative number = a lower noise  level?  
 
73,
Dick- K9OM
 
Here are some measurements using Spectrogram and broadband noise:  

FT-2000   --- MK V ---      IC-706     ------ K3 ------

Analog   DSP      MKIIG     Norm  BW=4   EQ

50   -34       -44     -49     -46        -35   -7    -35
100    -31       -24      -27      -40        -18    -6   -18
200    -17       -10   -9      -21          -5   -2    -5
300    -6       -4      -4      -11       -1    0    -1
400    -3   -2      -1        -5          0    0      0
600    -2        -1        0       -1          0     0     2
800    -1         -1       0        0       0    0     1
1000     -1        -1       0     -1          0    0   0
1200      0        -1   0       -2         0    0     0
1400      0   0       0     -1          0    0     -2
1600    -1        -2       -1       -2          0     0    -3
1800    -2        -3   -2       -3           0    0    -4
2000    -5       -5      -2       -4     -1    0    -5
2200     -7        -6      -3     -6         -2    0     -7
2400    -8        -8       -4       -8         -2     0    -8
2600    -10       -10   -6      -15          -3    0    -9
2700    -23     -13      -7      -27     -4    0   -10
2800     -34       -19     -11       -31         -8    0    -14
2900    -41       -32      -24      -33        -18     0   -24
3000    -50       -43   -36      -35        -58   0   -60
3100               -42               -67    0        
3200     -58       0    
3300                  0        
3400     0        
3500          0    
3600                  -1        
3700      -2  
3800                -4        
3900     -5
4000                      -13
4100                  -34
4150              -66

All measurements were made  at the speaker output for consistency.
All measurements were made in USB  mode with the default filter
settings.  FT-1000MP Mark V was measured  with both the analog
and DSP (100-3100 Hz setting) detectors.

The  two additional K3 measurements are 1) FM filter, BW=4.00
and FC=2.00 and 2)  "NORM" using the "pink EQ" settings (1.60=-3,
2.40=-5, 3.20=-6).  

Note the K3 audio amplifier is the cleanest hands down.  The other  
transceivers had noise floors at about -120 dBV (IC-706 mkIIg was
-100  dBV).  Except for what appear to be artifacts of the ADC
clock at 4, 8,  12, 16, 18 and 20 KHz the K3 out of band audio
noise is <140  dBV.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Don Wilhelm-4]

Dick,

I believe you are mis-interpreting the data.  This is the response of
the receiver to a broadband source.  Is the fact that this is from a
noise generator confusing you?  We are displaying the capability and
shape of the receiver response, and it has nothing to do with the fact
that the source is broadband noise.  Look at the broadband noise source
as if it were a LOT of signals, all of the same amplitude but of
slightly different frequencies, so close together that you cannot tell
where one ends and the other starts.
Within the receiver passband,  the ideal is 0 (all other levels are
referenced to that), and outside the passband there would ideally be no
response at all (a very large negative number) - that would indicate a
perfect filter with infinite skirt slope and a perfectly flat top.

The K3 has nearly the ideal response within the passband (all zeros)
while the MP varies a little bit (this is normal for a filter).
Outside the passband - take the 3100 Hz point for example - the lowest
response is better.  Here the MP had a response only 42 dB below the
maximum in-passband response while the K3 had a response that is 67 dB
lower than the peak within the passband.  So, out of the passband (and
at this point), the K3 is 27 dB more quiet than the MP.

73,
Don W3FPR

[hidden email] wrote:
> Interesting data but what am I missing here?  "Note the K3 audio  amplifier
> is the cleanest hands down".  Looking at the data below, doesn't  it show
> that in the 22 audio ranges from 50-3200hz that the MP has a  lower noise
> level in 12 out of 20 ranges and is about identical in  most of the others?  
> Doesn't a lower negative number = a lower noise  level?  
>  
>  
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html