[Elecraft] K2 receive sensitivity

[Paul Del Negro]

Don Wilhelm wrote:

>Paul,
>
>I am not certain your test is entirely valid.  If there is no atmospheric
>noise on the band you are using, you should notice no difference in level
>switching from a dummy load to an antenna.
>
>The bandwidth of the receiver will make a great difference as well, and that
>is both the IF bandwidth and the front end bandwidth.  The K2 does have the
>low pass filters at the receiver front end - some other receivers run with a
>wide open 'DC to Daylight' front end which will pick up more wideband noise.
>You are not necessarily comparing apples to apples with such a simplified
>subjective measurement.
>
>It would be much more informative to actually measure the MDS at a given
>receiver bandwidth and at the frequency of interest.  Measurements of that
>nature should be controlled and can be used for valid comparisons.
>
>73,
>Don W3FPR
>
>  
>
>>-----Original Message-----
>>
>>Hi to all on the reflector.  I'd like to put something out here and see
>>if others experience the same thing or if I possibly have a problem with
>>my K2 sn5834.  Someone (I don't remember who) mentioned that a great way
>>to test receive sensitivity is to simply check for an increase in noise
>>level when switching from a dummy load to a resonant antenna on a dead
>>band (like 10m is lately), and I am a great believer in that method.  I
>>have used it for years with various commercial and homebrew rigs.
>>So here's the deal.  K2 set for 10 meters, preamp off, antenna is
>>resonant wire (and also used a beam). When switching between dummy load
>>and antenna, there is no (or barely perceptible) change in receiver
>>noise output.  With the preamp on, the change is noticeable, as the
>>noise increases both with dummy load and antenna connected.  What I'm
>>concerned about is the preamp off situation, as all other receivers I
>>have tested do show a marked change in receiver noise when doing
>>this test.
>>    
>>
>
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>
>
>
>  
>
Thanks for your reply, Don... it has been my experience that there is 
always some level of atmospheric noise on 10 meters, even when the band 
is not open.  The method of sensitivity quick-test I described was 
endorsed by many notable amateurs, including the late Doug DeMaw, W1FB, 
who I'm sure you have heard of.   That's where I got the method from.  
But I guess what I'm asking of the guys on the reflector is whether or 
not they are experiencing the same result using this quick-test with the K2.
72 Paul N2PD