[Elecraft] KX3 LO injection

[Terry Conboy]

On 2011-06-02 1:25 AM, Julian, G4ILO wrote:
> Dave KK7SS wrote:
>> Just thought I'd ask, as there are two common ways to do it:
>> One is to shift the filter passband and the other is to adjust the LO
>> injection frequency.
>>
>> My IC7200 had the 'hiss' problem. Using IF shift would reduce it but would
>> also tend to muffle the audio. Didn't like that. :(
> But shifting the LO injection frequency would worsen the carrier
> suppression. I used to spend a lot of time fiddling with analog rigs trying
> to do the same thing. Got it sounding nice, then noticed that when I keyed
> the mic the output meter was showing a reading even though there was no
> modulation. :( I run my K3 in SSB with the filter centered on 1.4kHz and it
> sounds great to me.
>
> -----
> Julian, G4ILO. K2 #392  K3 #222.
I suspect the KX3 will use the equivalent of the so-called "phasing 
method" of SSB generation (but digitally, in DSP software).  I don't 
think there will be a xtal filter like in the older analog radios, so 
the carrier suppression shouldn't change.  All of the filtering (except 
perhaps for the baseband "roofing filter") will probably be via DSP.

Eventually, the Elecraft guys will give us more details of the radio 
design so we can eliminate the guesswork.

Keep clam,
Terry N6RY