scopeing filters for eventual diversity receive.

[Richard-3]

I'm planning to install a sub receiver eventually.  Now I need a CW
filter.  I'm considering buying two now, matched, with the second for
later use with the sub receiver.

I understand that the 5-pole filters need to be matched, but have the
impression that the 8-pole filters do not.

Is that right?  If so, I only need to buy one filter now.

Thanks
Rich
NU6T

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[Ed Muns, W0YK]

> I understand that the 5-pole filters need to be matched, but
> have the impression that the 8-pole filters do not.
>
> Is that right?  If so, I only need to buy one filter now

The 8-pole filters are described as having "a nominal 0 offset" and do not
need to be matched for diversity.  However, my 400Hz 8-poles are offset by
as much at 80Hz.  The ordering page doesn't provide for matching 8-pole
filters.  This is only an issue for the narrow filters and only if the
offset delta between the two filters is greater than 10-20Hz.  If two 8-pole
filters are offset, say, +60Hz and +80Hz, then you configure both for an
offset of +70Hz and will be fine for diversity receive.

Ed - W0YK
-----------------------------------------------
Ed Muns
Muns Vineyard - www.munsvineyard.com
FaceBook - www.facebook.com/munsvineyard

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[Jim Brown-10]

On Sat, 27 Mar 2010 15:09:02 -0700, Ed Muns wrote:

>However, my 400Hz 8-poles are offset by as much at 80Hz.  

I've observed that too.

73,

Jim K9YC



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[N5GE]

On Sat, 27 Mar 2010 15:09:02 -0700, "Ed Muns" <[hidden email]> wrote:

I matched all of my 8 pole filters by using the NGEN noise generator
and setting them for matching white noise pitch.

It seemed to work for me.

TOM, N5GE BT

73 ES GUD LUK
AR DE N5GE SK

[snip]

>
>The 8-pole filters are described as having "a nominal 0 offset" and do not
>need to be matched for diversity.  However, my 400Hz 8-poles are offset by
>as much at 80Hz.  The ordering page doesn't provide for matching 8-pole
>filters.  This is only an issue for the narrow filters and only if the
>offset delta between the two filters is greater than 10-20Hz.  If two 8-pole
>filters are offset, say, +60Hz and +80Hz, then you configure both for an
>offset of +70Hz and will be fine for diversity receive.
>
>Ed - W0YK

[snip]

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[N2TK]

How are you testing for offset? Sounds like I should check the offset on my
5 and 8 pole filters.

73,
N2TK, Tony


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jim Brown
Sent: Saturday, March 27, 2010 7:23 PM
To: Elecraft List
Subject: Re: [Elecraft] scopeing filters for eventual diversity receive.

On Sat, 27 Mar 2010 15:09:02 -0700, Ed Muns wrote:

>However, my 400Hz 8-poles are offset by as much at 80Hz.  

I've observed that too.

73,

Jim K9YC



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[Dave, G4AON]

Inject a clean signal to the K3, around S5 - S7 in level, go into the
CONFIG menu, adjust the filter offset (FLx FRQ) by rotating the main
tuning knob until the signal drops one S point then adjust it to the
other side until it again drops one S point. Set the offset to the
middle of the two extremes.

My 400 Hz 8 pole filter appeared to have more insertion loss than my 250
Hz 8 pole, setting the offset solved the apparent additional insertion
loss. My settings are -0.07 for the 400 Hz and -0.05 for the 250 Hz.

73 Dave, G4AON
K3/100 #80
-----------------------

How are you testing for offset? Sounds like I should check the offset on my
5 and 8 pole filters.

73,
N2TK, Tony
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[Brett Howard]

Why use the S-Meter for this?  Depending on where you are in that S-Unit
that can make you miss the center.  What you need is a relative dB
measurement.  Turns out that the only piece of test equipment that you
need is a K3.  

Center the signal in the passband.  Then hit disp and use VFO to get to
the AFV menu item.  Let it settle on a value and then turn clockwise one
more click.  You should then see 0dBV.  Then as you adjust things you
can go up and down until you find the -3.0dBV points of the filter.  Or
you can test to the two -6dBV points and then calculate the mean of your
two points.  Just as simple but less error prone.

~Brett (KC7OTG)

On Sun, 2010-03-28 at 16:10 +0100, Dave, G4AON wrote:

> Inject a clean signal to the K3, around S5 - S7 in level, go into the
> CONFIG menu, adjust the filter offset (FLx FRQ) by rotating the main
> tuning knob until the signal drops one S point then adjust it to the
> other side until it again drops one S point. Set the offset to the
> middle of the two extremes.
>
> My 400 Hz 8 pole filter appeared to have more insertion loss than my 250
> Hz 8 pole, setting the offset solved the apparent additional insertion
> loss. My settings are -0.07 for the 400 Hz and -0.05 for the 250 Hz.
>
> 73 Dave, G4AON
> K3/100 #80
> -----------------------
>
> How are you testing for offset? Sounds like I should check the offset on my
> 5 and 8 pole filters.
>
> 73,
> N2TK, Tony
> ______________________________________________________________
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>
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[N2TK]

Dave,
Tnx for the tip. In one K3 the 400 stayed at 0, and the 200 went from -.89
to -.84. In the other K3 the 500 went from -.75 to -.88 and the 200 went
from -.94 to -.96.

73,
N2TK, Tony
#311
#1435

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Dave, G4AON
Sent: Sunday, March 28, 2010 11:10 AM
To: [hidden email]
Subject: Re: [Elecraft] scopeing filters for eventual diversity receive.

Inject a clean signal to the K3, around S5 - S7 in level, go into the
CONFIG menu, adjust the filter offset (FLx FRQ) by rotating the main
tuning knob until the signal drops one S point then adjust it to the
other side until it again drops one S point. Set the offset to the
middle of the two extremes.

My 400 Hz 8 pole filter appeared to have more insertion loss than my 250
Hz 8 pole, setting the offset solved the apparent additional insertion
loss. My settings are -0.07 for the 400 Hz and -0.05 for the 250 Hz.

73 Dave, G4AON
K3/100 #80
-----------------------

How are you testing for offset? Sounds like I should check the offset on my
5 and 8 pole filters.

73,
N2TK, Tony
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