[Elecraft] K3 6/10M pre-amp

[Scott Manthe]

Maybe the signals are louder on the KX3, which would fool people into 
thinking it was more sensitive? I've always thought my K3 was adequate 
on 6 meters. Not gangbusters, but certainly adequate.

73,
Scott, N9AA


On 7/8/13 6:09 PM, Edward R Cole wrote:
> Been a lot of discussion on this topic so I decided to make some 
> "real" MDS measurements comparing my K3/10 (4340) and KX3 (475).  I 
> hope the columns read clear for everyone (I can create some charts on 
> my website, if not):
>
> Test set up:  XG3 + JFW 30-dB step attenuator + 6-inch of RG-58 w/BNC's
> The XG3 is installed in a Hammond "diecast aluminum" enclosure with 
> BNC feedthru adapter so the unit is fully shielded (I have made MDS 
> measurements using additional 20-dB coaxial attenuator to -157 dBm +/- 
> 2 dB.  That was using double-shielded coax whereas today's tests were 
> using ordinary RG-58 (so adds a little uncertainty on the minimum 
> signal).  MDS detector are my "ears" so that makes a bit more 
> subjective for absolute measurements.
>
> Both radios tuned with 2.8 KHz bw in USB, Elecraft's MDS spec is done 
> at bw = 500-Hz.
>
> 50.120 MHz
> Level (dBm)     K3+PRE         KX3+PRE(30-dB)     K3 (no preamp)
> XG3 off            S1                  S0 S0
> -73                  S9+5              S9 S8
> -107                S3                  S4
> -123                ---                   S1/S2
> -130                S1                   below MDS
> ANT                S2                   S2/S3 S0 (slight rise in noise 
> in speaker)
>
> 28.200 MHz
> Level (dBm)      K3+PRE        KX3+PRE(30-dB)
> XG3 off             S1                 S0
> -73                   S9+5             S9
> -107                  S4                S3
> -123                  ---                 S0
> -133                  S1                 Below MDS
>
> I also checked frequency using the K3 as reference (has EXREF) and the 
> KX3 was 50-Hz higher than the K3 on 6m and 40-Hz higher on 10m (I have 
> not done the temperature calibration for the KX3).  I did not measure 
> freq drift after transmitting.
>
> One would state that the K3 looks better than the KX3 for receiver 
> sensitivity (yet the KX3 hears 6m much better - hmmm?)
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> dubususa at gmail.com
> "Kits made by KL7UW"
> ______________________________________________________________