[Elecraft] New beta K3 firmware!

[Wayne Burdick]

The 6 kHz filter band-limits the transmit noise originating from the  
DAC and the transmit mixer to a bandwidth appropriate for AM and ESSB  
modes. The 15 kHz filter would allow a noise bandwidth over twice as  
wide.

This in-band noise "pedestal" could be 20-30 dB above the normal  
transmit noise floor if you were using a lot of mic gain and/or  
compression. If you were using high power in these modes, your signal  
would now be much more likely to bring up the receive noise floor at  
nearby stations.

Do you really want to create a 15-kHz wide swath of broadband noise  
when using ESSB or AM?

I don't. That's why I haven't modified the code to allow use of the FM  
filter for this purpose. I suppose it could be YAMU (yet another menu  
entry), forcing you to do at least a minimum amount of soul-searching  
before "going broadband" :)

73,
Wayne
N6KR


On Sep 21, 2012, at 3:09 PM, Thomas Horsten wrote:

> Hi Gary,
>
> The point is not to widen the SSB but to use the FM crystal filter  
> to limit
> it. The DSP does the actual shaping of the TX signal which will  
> still be
> the same width regardless of whether you're using the 6kHz filter or  
> the
> 12.5kHz FM one.
>
> The idea is to be able to use the FM filter for AM and ESSB as well  
> instead
> of filling up two precious filter slots, when what you may want/need  
> are
> closer filters on the low end (say, 400 and 200 Hz).
>
> 73, Thomas M0TRN
>
> On 21 September 2012 22:00, Gary Gregory <garyvk4fd at gmail.com> wrote:
>
>> Joe,
>>
>> I have to ask, why?
>>
>> In VK we have a 3Khz SSB BW written into our LCD's and yet some folks
>> consume 10Khz out here on a net which tears up a considerable  
>> amount of
>> spectrum.
>>
>> What advantage do you see to widen the ESSB?
>>
>> Not sure I follow your thoughts here, hence the question Joe.
>>
>> 73
>>
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