[Elecraft] KX3 BC Breakthrough

[Wayne Burdick]

Hi Paul,

The vast majority of KX3 users don't have any issues with strong AM broadcast stations. However, for those who do, we provide RX SHFT settings as well as control over preamp gain. These are the same signal-management strategies used by other companies using this receiver architecture. Typically, dropping preamp gain from 20 dB to 10 dB will do the trick, or you can use the 8-kHz shift setting. In either case, you only need to do this on affected bands.

Shifting the I.F. does bypass the roofing filter module, if applicable. However, this only changes the close-in dynamic range of the receiver by 8-10 dB, which still leaves the KX3 in the top 10 of all radios tested by Sherwood, etc. I still hope to provide a smaller shift that allows the use of FL2 (1500 Hz roofing filter) in narrowband operating modes.

The K3 uses a different architecture (superhet), which is inherently immune to narrowband AM IP2. But the KX3's primary application is as an ultraportable field radio, and we elected to keep it small and lightweight by using a quadrature-DC architecture. 

73,
Wayne
N6KR



On Aug 15, 2013, at 3:52 AM, "Paul Barlow" <paul.barlow at upcmail.ie> wrote:

> After being QRT for a number of years I'm returning to the air with a new
> call and location. I am seriously considering buying a KX3 (I have a K2 and
> a K1), but I'm a little concerned by reports of AM breakthrough (or whatever
> the right word is). I know this is because of the direct conversion
> architecture of the rig. I also understand that the IK can be shifted to
> 8KHz, which should solve the problem, but in doing so makes the narrower
> roofing filters and dual watch inoperable….