[Elecraft] KX3 Sherwood RX Test Numbers Posted

[Wayne Burdick]

Jim Brown wrote:

> Can you explain note "v?"

Hi Jim,

Footnote 'v' (on the 2-kHz IMD) actually refers to a measurement at a  
1-kHz spacing, which is not part of the comparison table:

    v:   At 1 kHz, performance is opposite-sideband rejection limited.

As you know, a quadrature direct-conversion receiver (such as the KX3  
or the Flex radios) depends on gain/phase balance to suppress the  
opposite-sideband signal. What Rob is referring to, here, is that when  
you do an IMDDR3 test at a very close offset (say 1 kHz), with the  
roofing filters enabled (i.e., using a zero I.F.), then the opposite- 
sideband signal might dominate the measurement. (This depends on the  
relationship between the interfering signal and the desired signal.)  
In his case this limited the measurement to an equivalent DR of 65 dB.

Our main goal for the KX3 was to provide maximum portability yet all- 
band/all-mode coverage. If your goal is to get the absolute best DR at  
very close spacings, then the K3 would be the better choice, given its  
narrow crystal filters and nearly infinite opposite sideband rejection.

I'll expand on this topic later.

73,
Wayne
N6KR