[Elecraft] K3S Birdy on 28MHz

[Wayne Burdick]

Hi Conrad,

"SIG RMV" is a function we created that shifts both the BFO and VFO by the same small amount in order to shift a spur out of the passband. 

The reason this is effective for many spurs is because they're the product of harmonics of the signal sources, not the fundamentals. For example, you may hear a spur that results from mixing of the 3rd harmonic of the VFO beating against the 9th harmonic of the BFO (any combination is possible). That's the nature of high-level mixers in superhet transceivers. 

SIG RMV shifts the VFO and BFO by the same amount *at their fundamentals*, but the spurs end up shifted by a multiple of this amount. Using the previous example, a 100 Hz shift at the fundamental might shift the VFO 300 Hz and the BFO 900 Hz. (Often the multiples are much higher -- I've seen them up to 21.) Doing this often moves the spur out of the passband, while having an insignificant effect on the filter center frequency (these are fixed because of the crystal filters).

You can create SIG RMV entries separately for both the main and sub receivers on the K3/K3S.

73,
Wayne
N6KR



> On Dec 26, 2020, at 3:44 AM, Conrad PA5Y <g0ruz at g0ruz.com> wrote:
> 
> Thanks to G4ZTR I found "SIG RMV" in the Config Menu. It worked a treat. What exactly does this do. I noticed that the passband changed but I was able to restore it by changing the centre frequency. It worked great!
> 
> 
> 
> Many thanks John.
> 
> 
> 
> 73
> 
> 
> 
> Conrad PA5Y
> 
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