Filter Selection

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Filter Selection

Buck - k4ia
Wondering if a consensus was developing about  the choice of roofing filters.
 Seems like there a too many to choose from.  Lacking detailed plots for each
one, I can't believe there is that much  difference between say a 500hz 5
pole and a 400hz 8 pole or a 200 hz 5 pole vs a  250 hz 8 pole.  Sure the 5 poles
will have wider skirts but will you be  able to hear the difference?  

I would think the 500hz 5 pole would  be fine for CW and the stock 2.7 would
be fine for SSB.  Maybe add the 1.8  if you do a lot of SSB contesting.    I
have an Orion so I am  used to roofing filters - they are a dramatic
improvement over the wide open  front ends of the YaeComWoods but you don't need to go
crazy with multiple  filters since the DSP does all the work and the roofing
filters only make a  difference in really crowded conditions.

Comments?

k4ia
Craig  "Buck"
Fredericksburg, Virginia USA  




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Re: Filter Selection

Matt Zilmer
I doubt a consensus would ever develop over such a contentious issue,
but let's try for a reasonable compromise.

This is a plan, not that it's perfected yet -

2.7 KHz is already in the K3 and has proven quite workable under most
CW/SSB conditions.

500 Hz looks effective enough and, as with other filters, will be
augmented in effect by the DSP's capabilities.

6 KHz FM filter would cover all wideband and general purpose SWL stuff
(with the KBPF3).

I'd add the 1.8 or 2.1 KHz filter for contesting too.   Good thought.
For me - later.

The saving grace is the DSP.  Damn - that *perfects* the best HF RX
around, imho.  You are quite right about that....

:)

matt, WA6EGJ
K3 s/n 24


On Fri, 16 Nov 2007 21:32:28 -0500 (EST), you wrote:

>Wondering if a consensus was developing about  the choice of roofing filters.
> Seems like there a too many to choose from.  Lacking detailed plots for each
>one, I can't believe there is that much  difference between say a 500hz 5
>pole and a 400hz 8 pole or a 200 hz 5 pole vs a  250 hz 8 pole.  Sure the 5 poles
>will have wider skirts but will you be  able to hear the difference?  
>
>I would think the 500hz 5 pole would  be fine for CW and the stock 2.7 would
>be fine for SSB.  Maybe add the 1.8  if you do a lot of SSB contesting.    I
>have an Orion so I am  used to roofing filters - they are a dramatic
>improvement over the wide open  front ends of the YaeComWoods but you don't need to go
>crazy with multiple  filters since the DSP does all the work and the roofing
>filters only make a  difference in really crowded conditions.
>
>Comments?
>
>k4ia
>Craig  "Buck"
>Fredericksburg, Virginia USA  
>
>
>
>
>************************************** See what's new at http://www.aol.com
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

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Re: Filter Selection

Ken Kopp
I've just completed my K3, S/N 56.

Here's one minor item ... other than cost ... related to
choosing between the 5-pole and 8-pole filters ...

I believe the 5-pole units require entering their individual
(and each different) off-sets into the radio during initial filter
set-up.  There's a table in the manual where the builder is to
note the off-sets as the filters are installed.  This would need
to be done each time there is a reason to re-configure the
filters ... as in moving them from slot-to-slot to make room
for an added filter.  I view this as a "pain". The 8-pole (Inrad)
filters don't require this step.  

I have 6 kHz, 2.8 kHz, 1.8 kHz, 1 kHz and 400 Hz filters,
all 8-pole units and I'm really glad I made the extra investment.

Even with my limited experience with the K3, it's SMOOTH!
A wonderful radio!

73! Ken Kopp - K0PP
K2 #5665
K3 #56
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RE: Filter Selection

Greg - AB7R
Hi Ken.  While it is an extra step I don't see how it would be a "pain". ??

The offset is also on the filter itself.  Since moving filters around
already necessitates going into the filter setup in CONFIG, it's
not hard to go to FL OFS and dial in the offset on the filter.

73
Greg
AB7R


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Ken Kopp
Sent: Friday, November 16, 2007 8:19 PM
To: [hidden email]
Cc: [hidden email]
Subject: Re: [Elecraft] Filter Selection


I've just completed my K3, S/N 56.

Here's one minor item ... other than cost ... related to
choosing between the 5-pole and 8-pole filters ...

I believe the 5-pole units require entering their individual
(and each different) off-sets into the radio during initial filter
set-up.  There's a table in the manual where the builder is to
note the off-sets as the filters are installed.  This would need
to be done each time there is a reason to re-configure the
filters ... as in moving them from slot-to-slot to make room
for an added filter.  I view this as a "pain". The 8-pole (Inrad)
filters don't require this step.

I have 6 kHz, 2.8 kHz, 1.8 kHz, 1 kHz and 400 Hz filters,
all 8-pole units and I'm really glad I made the extra investment.

Even with my limited experience with the K3, it's SMOOTH!
A wonderful radio!

73! Ken Kopp - K0PP
K2 #5665
K3 #56
[hidden email]
or
[hidden email]

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Filter Selection

Ken Kopp
Well, I did say it's a "minor" item ... (:-))

Perhaps "chore" or "avoidable step" would have been
a better choice.

73! Ken Kopp - K0PP
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