[Elecraft] My Five Filters

[Don Wilhelm]

Phil,

Don't get so stressed.  My K3 has 3 open filter slots, and it does not 
concern me at all.
How much serious contesting do you do - how much serious DX Chasing?
Consider my logic:  The DSP filtering alone is really good and will 
handle conditions under more casual situations than the above.  Just 
dial in the filtering you want.
The "rub" comes in when there are a lot of strong signals in the Roofing 
filter passband.  You may not hear them with the DSP filtering tightened 
up, but they will activate the hardware AGC and will de-sense the 
receiver.  The reality of that happening are not usually present in 
normal operating, but will be present in serious contest and DX Chasing 
situations.
My opinions:
1) A wide CW roofing filter is of little value.  There will be so many 
signals in the passband that at least one is likely to activate the 
hardware AGC, so I figure that the normal 2.7/2.8 kHz filter with DSP 
set somewhere between 700 and 1000 Hz width will be about as good as the 
1000 Hz filter.
2) If you are a SSB contester, go for the 1.8 filter (or even the 1.5 
from Inrad) if you want to operate in extreme SSB conditions.
3) For CW contesting and DX Chasing, you will likely want a roofer in 
the  400 Hz or even 250 Hz range - which one depends on how much you are 
willing to dig for reception under crowded conditions.  As the filter 
gets more narrow, the more critical (i.e. slowly) one must tune, or the 
desired signal will suddenly disappear outside the passband.
4) For Data modes where one tunes with the VFO rather than clicking on a 
waterfall display, a 400 Hz filter is a good thing to have - some would 
argue that a filter in the 200 to 300 Hz range would be better, and that 
is logical too - which depends on how critical you wish to tune and how 
important that elusive contact is to you.

OK, I have not said which filters to use, but for me, the ideal set 
would be 13 kHz (discard if you don't want to do FM), the 6 kHz filter 
if you want to transmit AM or ESSB (the 6 kHz is good for SWLing, 
although the 13 kHz will do fine for that too).  The 2.7 or 2.8 kHz 
filter is required.  Then the 1.8 (alternately the 1.5) for SSB 
contesting/DXing.  The 400 Hz filter for normal CW, although for general 
tuning I like 700 Hz - do that with the 2.7, 1.8, or 1.5 kHz filter and 
the narrowed DSP filter.  For extreme CW or data mode work, any roofing 
filter in the 200 to 300 Hz range will do for me.

That fills the slots - 13 kHz, 6 kHz, 2.7/2.8, 1.8/1.5 and 400/200-300 
range.  If you do not want FM, then you will have 1 empty slot.
OK, that is the ideal for me, and I am building on it - I currently have 
the 13 kHz and the 2.7 kHz filters installed.  Right now, I am not 
interested in serious DXing or contesting, so until that bug bites me, 
the other slots will remain empty.

Those are my thoughts and the reasons I have chosen this path - YMMV, 
make up your own criteria based on your operating desires.

73,
Don W3FPR

Phil Hystad wrote:
> Each morning I wake up stressed because I do not have all five filter slots populated.  There is a hole in my K3 and it bothers me.  I had been saving the high end for a FM filter but now decided that "No, I won't be doing FM with my K3".  So, my filters are: 400 Hz, 1000 Hz, 2.7 KHz (5-p), 6 KHz.
>
> I am thinking of adding another filter and I am thinking of the 250 Hz because I prefer CW over SSB and I think I would get more use out of that end of my filter lineup.
>
> So, is it overkill to have the 250 Hz and the 400 Hz filters in the same K3?
>   
>