Why all those filters - K3

[Fred (FL)]

Looking at the new K3 order form - one is faced
with a potential order selection of some 8 or
more filters.  And some others coming on the
scene, have been mentioned. Many are called roofing
filters.

I'm hoping Elecraft will explain the use, benefit
and potential shortcoming of one's K3 - if they do
or do not order any or all of these filters.

For example, if I just want to have a slightly
better narrow CW and narrow SSB filter selectability
- which of all these - would be natural to order?  I'm
surprised of the need to order all of these filters in
a 2007 DSP-based radio.  For example, for Icom's
IC-7000 - there are no optional filters to
buy.

Filters have gotten to be big ticket items, for rigs
that could need them - ala $135 for a single SSB
filter for a IC-703.  $80 bucks a wack, for a
IC-706MKIIG.   And again - none are listed
in the options list for a IC-7000.  How do they
perform the roofing function, and selectability
function?

Fred, N3CSY
.....learning, learning 2007



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[Don Ehrlich]

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.

Remember, the DSP will do a good job of filtering without any crystal
filters.  As I understand it the radio will work well with none of the
optional crystal filters installed.  By the time I get to that point I am
sure some consensus will have formed as to the best way to approach filter
choice for various operating preferences.

Don K7FJ

> Looking at the new K3 order form - one is faced
> with a potential order selection of some 8 or
> more filters.  And some others coming on the
> scene, have been mentioned. Many are called roofing
> filters.
>
> I'm hoping Elecraft will explain the use, benefit
> and potential shortcoming of one's K3 - if they do
> or do not order any or all of these filters.
>
> For example, if I just want to have a slightly
> better narrow CW and narrow SSB filter selectability
> - which of all these - would be natural to order?  I'm
> surprised of the need to order all of these filters in
> a 2007 DSP-based radio.  For example, for Icom's
> IC-7000 - there are no optional filters to
> buy.
>
> Filters have gotten to be big ticket items, for rigs
> that could need them - ala $135 for a single SSB
> filter for a IC-703.  $80 bucks a wack, for a
> IC-706MKIIG.   And again - none are listed
> in the options list for a IC-7000.  How do they
> perform the roofing function, and selectability
> function?
>
> Fred, N3CSY
> .....learning, learning 2007
>
>
>
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[dj7mgq]

> I'm hoping Elecraft will explain the use, benefit
> and potential shortcoming of one's K3 - if they do
> or do not order any or all of these filters.

More importantly, that the full specs are released. Factors such as
group delay can be very important when judging a filter for a purpose.

Why so many filters - in very loose terms, to "protect" everything
after filter and not let more reach the back end than necessary. You
do not want the ADC overloading or the AGC reacting to signals which
you can not hear.

I am glad that Elecraft is offering a large range of filters, which
should allow one to tailor the radio to needs and budget. I am holding
back on the filters until I know more. Which filters and how many
really depends on your use of the radio. For some, 200Hz/250Hz filters
will be very important (40m in EU especially during contests) and for
others senseless overkill. I will likely end up with a whole
collection of filters in my K3, and am very very curious about the
variable bandwidth filters.

vy 73 de toby
--
DD5FZ, 4N6FZ (ex dj7mgq, dg5mgq, dd5fz)
K2 #885, K2/100 #3248
K3/100 #??? (< #200)
DOK C12, BCC, DL-QRP-AG

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[Thom LaCosta]

On Fri, 4 May 2007, 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.

Hmmm, didn't see no filters as an order option.

Thom

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[Dick Dickinson]

I think if I were to order, I'd take only the provided 2.7 KHz filter and
wait for the variable one(s) to become available.


Regards,
Dick - KA5KKT

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Thom LaCosta
Sent: Friday, May 04, 2007 5:53 PM
To: Don Ehrlich
Cc: [hidden email]; Fred (FL)
Subject: Re: [Elecraft] Why all those filters - K3

On Fri, 4 May 2007, 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.

Hmmm, didn't see no filters as an order option.

Thom

www.baltimorehon.com/                    Home of the Baltimore Lexicon
www.tlchost.net/hosting/                 Web Hosting as low as 3.49/month
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[Mike Harris-9]

G'day,

Not seen any mention of the 1.0kHz roofing filter.  Good looking passband
and for me it would be good up front for general CW.  My K2 CW filters are
set for 1.0kHz, 700Hz, 400Hz and 200Hz.  I mainly use 700Hz, it gives
presence and drop to 400Hz if really necessary.  200Hz just seems too
dead, though nothing wrong with the signal level.  My DSP audio filters
are set just a little tighter to clean up the ultimate rejection.

It has been mentioned that the K2 DSP noise reduction works better with a
bit wider source spectrum to chew on so 1.0kHz looks like a good starting
point with maybe something tighter if AGC pumping is a problem during
contests.

Regards,

Mike VP8NO

----- Original Message -----
From: "Fred (FL)" <[hidden email]>
To: <[hidden email]>
Sent: Friday, May 04, 2007 4:37 PM
Subject: [Elecraft] Why all those filters - K3


| Looking at the new K3 order form - one is faced
| with a potential order selection of some 8 or
| more filters.  And some others coming on the
| scene, have been mentioned. Many are called roofing
| filters.
|
| I'm hoping Elecraft will explain the use, benefit
| and potential shortcoming of one's K3 - if they do
| or do not order any or all of these filters.

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[Martin AA6E-3]

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.
 >
 > Remember, the DSP will do a good job of filtering without any crystal
filters.  As I understand it the radio will work well with none of the
optional crystal filters installed.  By the time I get to that point I
am sure some consensus will have formed as to the best way to approach
filter choice for various operating preferences.
 >
 > Don K7FJ
 >
 >
 >> Looking at the new K3 order form - one is faced
 >> with a potential order selection of some 8 or
 >> more filters.  And some others coming on the
 >> scene, have been mentioned. Many are called roofing
 >> filters.
 >>
 >> I'm hoping Elecraft will explain the use, benefit
 >> and potential shortcoming of one's K3 - if they do
 >> or do not order any or all of these filters.
 >>
 >> For example, if I just want to have a slightly
 >> better narrow CW and narrow SSB filter selectability
 >> - which of all these - would be natural to order?  I'm
 >> surprised of the need to order all of these filters in
 >> a 2007 DSP-based radio.  For example, for Icom's
 >> IC-7000 - there are no optional filters to
 >> buy.
 >>
 >> Filters have gotten to be big ticket items, for rigs
 >> that could need them - ala $135 for a single SSB
 >> filter for a IC-703.  $80 bucks a wack, for a
 >> IC-706MKIIG.   And again - none are listed
 >> in the options list for a IC-7000.  How do they
 >> perform the roofing function, and selectability
 >> function?
 >>
 >> Fred, N3CSY
 >> .....learning, learning 2007
 >>
 >>
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[Don Wilhelm-3]

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.
>  >

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