2.8 Khz vs 2.7 Khz roof

[Ken817821]

I am looking for something somewhere that will help
me decide between the two.

Ken
_______________________________________________
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

[S Sacco]

How about this: All the K3's sent to VP6DX had the 8 pole filters.  I
presume that was for a reason.

I

On Thu, Apr 3, 2008 at 2:39 PM, Ken <[hidden email]> wrote:

> I am looking for something somewhere that will help
>  me decide between the two.
>
>  Ken
>  _______________________________________________
>  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
>

_______________________________________________
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

[Don Wilhelm-4]

Ken,

Examine your operating desires for the correct answer for you.  If most
of your operation is casual, the 5 pole filters will do just fine -
remember that the DSP provides the ultimate selectivity.
If you are heavy into serious contesting or DX chasing and other
situations where you will be operating in a crowded band with nearby
strong signals, then you may see a slight benefit with the 8 pole filters.

Eric Swartz has a nice writeup on the Elecraft website that may provide
some additional information for your decision making.

73,
Don W3FPR

Ken wrote:
> I am looking for something somewhere that will help
> me decide between the two.
>
> Ken
>
>  
_______________________________________________
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

[Darwin, Keith]

-----Original Message-----

All the K3's sent to VP6DX had the 8 pole filters.  I presume that was
for a reason.

-------------------------

Yes, but the reason may have had as much to do with marketing, wanting
to make SURE the rig puts it's best foot forward, as it did with
actually needing 8 poles.

I think this one is a rather easy choice.  If you're not sure, go with
the stock 5 pole filter.  It's free, after all.  Use the rig and see how
it does.  If you're still wanting more, get the 8 pole filter.

Or, get the 8 pole filter right off the bat.  Put both in the rig and
A/B switch between them.  Then report back here as to what difference
you heard.


- Keith N1AS -
- K2 5411.ssb.100 -
- K3 TBD -

_______________________________________________
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

[Vic K2VCO]

S Sacco wrote:
> How about this: All the K3's sent to VP6DX had the 8 pole filters.  I
> presume that was for a reason.

Yes, the 8 pole ones were sourced from INRAD and were available off the
shelf. The 2.7's weren't ready yet!
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
_______________________________________________
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

[Tom Hammond-2]

Actually, I believe the reason was AVAILABILITY!

When the VP6DX K3's shipped, I don't believe the 2.7kHz filters
were available yet!  And I don't believe the 500 Hz 5-pole's
were available at that time either...

73,

Tom   N0SS


At 14:46 04/03/2008, Darwin, Keith wrote:

>-----Original Message-----
>
>All the K3's sent to VP6DX had the 8 pole filters.  I presume that was
>for a reason.
>
>-------------------------
>
>Yes, but the reason may have had as much to do with marketing, wanting
>to make SURE the rig puts it's best foot forward, as it did with
>actually needing 8 poles.
>
>I think this one is a rather easy choice.  If you're not sure, go with
>the stock 5 pole filter.  It's free, after all.  Use the rig and see how
>it does.  If you're still wanting more, get the 8 pole filter.
>
>Or, get the 8 pole filter right off the bat.  Put both in the rig and
>A/B switch between them.  Then report back here as to what difference
>you heard.
>
>
>- Keith N1AS -
>- K2 5411.ssb.100 -
>- K3 TBD -
>
>_______________________________________________
>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

_______________________________________________
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

[Joe Subich, W4TV-3]

Ken,

> I am looking for something somewhere that will help
> me decide between the two.

I went back and forth several times before I finally decided
to go with the 8-pole filters.  

1) The 2.8 Khz filter is actually a bit tighter than the
   2.7 Khz filter.  As W4ZV writes:  

> 1.  6 dB bandwidth and 6/60 dB shape factor:
>
> Filter  BW(-6dB)     Shape Factor
>
> 2700    2910*            2.9
> 2800    2888             1.6
>
> *The 2.7k may have wider BW than the 2.8k.  This is
> Elecraft's measurement and my 2.7k closely agrees with it.

2) If you extend the analysis to the skirts, the 2.8 KHz filter
   shows some significant bandwidth advantage at -30 dB.  Using
   a simple linear skirt approach I first used for comparing
   the CW filters we see:

>               2700      2800
> -------------------------------------------------
>     - 6dB     2910      2888  Hz
>     -60dB     8329      4620  Hz
>      slope    50.18     16.03 Hz/dB  
>
>     -10dB     3311      3016  Hz
>     -20dB     4315      3337  Hz
>     -30dB     5319      3657  Hz
>     -40dB     6322      3978  Hz
>     -50dB     7326      4299  Hz

While the shape/width of the roofing filter is not critical,
the added selectivity can't help but be some benefit when the
strong station fires up 2.5 KHz away.  

3) Eric indicates that the 8-pole filters are tested to a
   higher standard than the 5-pole filters.  They will have
   less filter IMD than the 5-pole filters.

For me, the little things added up.  I decided "better safe
than sorry" was the best course of action ... I ordered the  
8 pole filter up front rather than possibly regret not doing
so every time I used the radio.  However, the second receiver
will have the 2.7 KHz filter.  

73,

   ... Joe, W4TV
 

_______________________________________________
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