Editor's note:

Ed Hare - W1RFI (the ARRL lab manager) posted the following on the rec.radio.amateur.policy newsgroup (Jan 15, 2001):

"Speaking of dynamic range, the best dynamic range ever measured in the ARRL Lab at 5 kHz spacing belongs to the Elecraft K2 on 20 meters."

Subject: FW: Re: Minimum discernable signal
Date: Fri, 12 Jan 2001 
From: "Tracy, Michael, KC1SX" <mtracy@arrl.org>

Here's an excerpt from a recent discussion on the 160M reflector that I thought you might be interested in. Tom Rauch, W8JI (of Ameritron fame) had said that 20 kHz numbers were not as important as numbers closer in. I had speculated that 20 kHz numbers should reflect the relative performance at closer spacings, then decided to check to see if I was right.

I compiled a list of BDR and IMDDR figures at 5 kHz, and these are listed below. Also, in checking the data, I noted that the BDR for the K2 at _1 kHz_ spacing was 116 dB, making it a better performer than most of the other rigs were at 5 kHz! (I didn't check the other rigs at 1 kHz, but they are always worse as you get closer).

Of course, I realize part of this stems from the single-conversion architecture, but it still has "wow" value! :)

73, Michael, KC1SX

Subject: Close-in dynamic range comparison: K2 vs. "big rigs"
Date: Fri, 12 Jan 2001 14:21:45 -0500
From: "Tracy, Michael, KC1SX" <mtracy@arrl.org>
To: "'elecraft@qth.net'" <elecraft@qth.net>

Hi All,
Just thought you folks would like to see this too. I got involved in a discussion on receiver dynamic range on another list and one of the fellows there suggested that close-in dynamic range was perhaps more important than the ARRL lab "standard" spacing of 20-kHz (personally, I think you need to look at as much as possible to get the most accurate "big picture"). 

In response to this fellow's post, I did some research on dynamic range at 5 kHz spacing for various radios that we have tested for this (only the ones we have expanded reports on). Here is a copy of my findings:

I went through a number of swept dynamic range test data. Here is the 5-kHz data for the rigs I checked:

(In alphabetical order...)

If anyone needs a good explanation of what these things mean, please see my recent posts to the top band list:

http://lists.contesting.com/_topband/200101/date.html 

72, Michael Tracy, KC1SX