[Elecraft] kx3 receiver versus K3s receiver

[Brendon Whateley]

I'm not sure why you would think this is a problem, the "other side" signal
is removed by the I/Q decoding technique, not by filtering. The filters do
the job of roofing filters, reducing and removing near in strong signals --
from the IF signal that just happens now to be at baseband frequencies.

If I'm missing something, please educate me on what I'm missing?

- Brendon
KK6AYI

On Mon, Jan 9, 2017 at 10:24 AM, K9MA <k9ma at sdellington.us> wrote:

> The KX3 "roofing filters" are audio filters.  (I wouldn't even call them
> "roofing" filters.)  They are analog filters, which can improve rejection
> of adjacent signals which might overload the ADC.  They will not, however,
> reject the "audio image", on the other side of zero beat.  I'd expect,
> especially during contests, the the effect would show up once in a while,
> probably making a weak signal totally unintelligible.  Has anyone noticed
> this effect?  Especially on CW, it would be fairly unlikely, as the
> interfering signal would have to fall within the narrow passband on the
> other side of zero beat.
>
> 73,
>
> Scott  K9MA
>
>
> On 1/9/2017 11:54, Ignacy wrote:
>
>> Perhaps as it should be. A bigger and more expensive radio is a better
>> radio
>> but one cannot take the bigger radio everywhere. I assume you had roofing
>> filters in KX3.
>>
>> I used KX3 directly driving Expert 1.3k for at Easter Island during CQ WW
>> SSB and a few days later in CW. KX3 was reliable and worked pretty well.
>> But
>> I had a feeling that discerning call signs in pileups was a bit worse in
>> KX3. Also, a better speech processor makes K3 about 1-2 S stronger than
>> KX3
>> at same peak power so no one can win a SSB contest with KX3. But KX3 is
>> about 20% weight and 10% of volume.
>>
>> Ignacy, NO9E
>>
>>
>>
>> --
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>
>
> --
> Scott  K9MA
>
> k9ma at sdellington.us
>
>
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