[Elecraft] K3 for CW

[Joe Subich, W4TV]

Thomas,

On 7/5/2012 11:55 AM, Thomas Horsten wrote:
 >
> You may say this and it may be true in theory, but if you have a
> 400Hz filter and are listening on an otherwise clear segment of the
> band with a single relatively weak signal in the centre of the
> passband, try widening from 400Hz to 450Hz,

This is the wrong test as you significantly change bandwidth when
going from 400 Hz with the 400 Hz roofer to 450 Hz with the 2.7
or 2.8 KHz roofer.

The correct test is to set your DSP bandwidth to 300 Hz and switch
roofers while making no other changes.  Under those conditions -
unless you are listening to a very busy band with may strong local
signals - if you can hear a difference you are probably a science
fiction or fantasy writer.

> Personally I have not had any need for anything narrower than 400Hz,
> although I would love a 200Hz filter if there was room for 6, but my
> lineup is FM, AM 6kHz, 2.7, 2.1, 400, so I don't have room for any
> more.

It is an absolute shame that we are still stuck with the FM/AM filter
limitation after all this time.  The FM filter (+/-6.5 KHz @-6dB and
about +/- 10 KHz at -60dB) is more than satisfactory to remove any
transmit image at 30 KHz offset (after all, it works in FM).  I have
never been able to detect any image response (transmit or receive)
with the FM filter in AM or ESSB when I tell the K3 it's and AM
filter.


73,

    ... Joe, W4TV



On 7/5/2012 11:55 AM, Thomas Horsten wrote:
> Vic,
>
> You may say this and it may be true in theory, but if you have a 400Hz
> filter and are listening on an otherwise clear segment of the band with a
> single relatively weak signal in the centre of the passband, try widening
> from 400Hz to 450Hz, in my case switching to the 2.1kHz filter. If you
> still believe there is no reason for the narrower filter, IMHO you need
> your hearing checked [no offense intended]. Or try telling the K3 that it's
> really a 500Hz filter and do the same from 500 to 550Hz, same effect.
>
> Personally I have not had any need for anything narrower than 400Hz,
> although I would love a 200Hz filter if there was room for 6, but my lineup
> is FM, AM 6kHz, 2.7, 2.1, 400, so I don't have room for any more.
>
> 73, Thomas M0TRN
>
> On 5 July 2012 16:51, Vic K2VCO <k2vco.vic at gmail.com> wrote:
>
>> The ONLY time you need a narrower filter is when there is a signal that is
>> about S9+20 or
>> greater that is outside the DSP bandwidth that you have selected but still
>> within the
>> bandwidth of the selected filter.
>>
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