[Elecraft] Why all those filters - K3

[Don Wilhelm]

OK folks.

That makes good sense to me.  I have been arguing the consequences of 
using a wide filter mainly to enhance awareness of the facts as I know 
them.  I really have only sketchy information at this point (no 
'hands-on experience), so my response is theoretical and based on a few 
pieces of information that Wayne has provided both on the reflector and 
privately.

The real facts are: 1) I will order my initial K3 with only the stock 
2.7 kHz filter.  Everything else will have to be add-ons - this is a 
necessity based on my ham radio budget at this time (taxes have just 
been recently paid and insurance is due!).
2) there is promise of a variable bandwidth filter in the works.  I will 
wait to see what it will provide before ordering any other filter.  I 
expect the variable filter may be of the Cohn design which is great for 
CW and SSB, but may not meet my needs for group delay since I am 
interested in performance with data modes.  The rounded nose of several 
of the filters shown in one of the references Eric made do hold promise 
for a good group delay characteristic, but my guess is only a guess, 
further information is necessary.

My best recommendation at this time: Understand the consequences of 
depending on a wide roofing filter while making your decisions - if you 
choose only the wide filter, live with it for a while.  Additional 
filters can be ordered after determining your individual needs, so if 
you find yourself in a situation where a more narrow filter will be 
beneficial to your operation, order it at that time.  Someone else's 
operating experience and priorities may not be equal to yours.  The 
information I have so far is that the major benefit to a narrow roofing 
filter is substantial reduction in AGC 'pumping'.

73,
Don W3FPR

Martin AA6E wrote:
> Don, the voice of sanity...
> 
> As an Orion owner considering the K3, I am aware of quite a few folks in 
> the Orion world who assume that ordering their rig with "all the 
> filters" is going to be better than taking the standard factory option 
> (4 filters: 1, 2.4, 6, and 20 kHz).
> 
> In fact, extra roofing filters only help you when you're working in very 
> hostile band conditions, like contesting.  For normal mortals (me), the 
> standard filters have been fine.
> 
> Whether the K3 would need more than one roofing filter completely 
> depends on your operating style, in my opinion.  So, if in doubt, it's 
> very reasonable to start with the one standard filter and add more as 
> needed.
> 
> If you add the second receiver, I think you have to decide all over 
> again which filters you want to add to _it_.  (I assume the first and 
> second Rx do not have to be equal.  One may have the general coverage 
> option, for example, and the other not.)
> 
> I certainly like the modular approach that lets you ease into the K3 
> world at a reasonable cost.
> 
> 73 Martin AA6E
> 
> Don Ehrlich wrote:
>  > I ordered mine with no crystal filters.  They can always be installed 
> later and by then I will have learned enough to know what I really want 
> or need.
>  > And ... I know I am not wasting my money with a hasty decision.
>  >