[Elecraft] K3 6m pre-amp

[K3KO]

Not 0.8 it is 0.08 microvolts for no preamp
K3KO

K3KO wrote:
> 
> 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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> 
> 

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