[Elecraft] K3 Filter question - SSB

[Ian White GM3SEK]

Al Lorona wrote:
>
>1.8 kHz is deemed better than 2.1 kHz, and 1.5 kHz is deemed better 
>than both.
>
>But at some point intelligibility itself suffers because you start to 
>eliminate the signal you're trying to copy in the first place.
>
>I for one suffer from a type of listener's fatigue when forced to copy 
>SSB signals in anything less than about 2.2 kHz or so.
>
>Others folks suffer from hearing loss and need to hear as much of 
>the voice frequencies as possible. 1.8 kHz just doesn't work for many 
>of these folks.
>

Here's some more individual data.

Although my hearing cuts off sharply at about 2.5kHz, I love the 1.8kHz 
crystal filter for heavy QRM. That Inrad filter was originally purchased 
for the 'narrow SSB' slot of my old FT-1000MP, and  I'm so glad that I 
kept it for the K3.

The 1.8kHz filter also works very well for my wife and other guest 
operators who don't have hearing loss.  In our typical contest QRM 
conditions (running W/VE with the whole of Continental Europe right 
behind us) the narrower filter helps to eliminate the high-pitched 
splatter which we find the most tiring.

Unlike a 1.8kHz DSP filter with a 2.5kHz roofing filter, the 1.8kHz 
crystal filter also avoids artefacts caused by pumping of the hardware 
AGC loop by strong signals in the gaps between the wider and the 
narrower passband.

The 1.8kHz filter does require careful initial setting of the center 
frequency to obtain the best possible intelligibility; but those 
settings will then require very little further adjustment. In other 
words, they make a very effective working compromise to maximize the QSO 
rate.

The 1.8kHz crystal filter is switched in at a DSP setting of 1.9kHz to 
avoid excessive narrowing of the passband. I would certainly agree that 
1.5kHz is too narrow, because almost every voice would then require its 
own critical tuning.

>If you're okay with such narrow bandwidths, more power to you, but you 
>can't make blanket statements about them being equally effective for 
>everybody.
>
But neither can anyone else make blanket statements about them being 
INeffective.

The fairest that anyone can say is, "If you don't like the 1.8kHz DSP 
setting, then don't even think about buying the crystal filter. But if 
you do like 1.8kHz DSP, you might like the crystal filter a lot."


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek