[Elecraft] K3 & ADAT ADT-200A by HB9CBU

[John A. McCabe]

David Cutter wrote:
> Some folk suffer extremely strong QRM from broadcasters on 40m 
> (particularly on the east coast of Scotland) and to them there is a 
> real desire for the best possible gear to hear weak stations amongst 
> huge bc signals from Europe.  That's where receivers like the Perseus 
> and others come in to their own.
>
>

Hi David,

Yes I can see your point, and I am certainly not questioning the benefit 
of High Dynamic range receivers in those situations. I guess what I am 
having a hard time understanding how it would be possible for any 
receiver, regardless of the dynamic range of the receiver, to receive a 
weak signal 2 Khz away from, say a 80db over 9 broadcast or other 
signal. Would not the IMD, sidebands, and splatter from the broadcast 
station itself be so severe as to prevent this? Or am I overstating the 
effects of transmitted phase noise and IMD? As I mentioned in my 
previous post, there is no way I could see operating 2 Khz away from the 
very strong signal of my  ham neighbor. His transmitted IMD would be way 
too severe. But  I can easily operate 20 Khz  or more away with the K3.  
To me, any minor difference in close in dynamic range between say the 
Perseus and the K3 is of little or no importance in this situation. I 
could not receive a weak signal so close to such a strong signal anyhow 
because of his transmitted IMD. But the wider spaced number's matter a 
great deal, and that is what concerns me when I see a 117-123db BDR as 
compared to 140db at wider spacings.

73,

John, KD8K