K3 8 pole filter offsets

[Dave, G4AON]

Since obtaining an 8 pole 250 Hz filter to compliment my 8 pole 400 Hz
filter, I have been puzzled as to why the 400 Hz filter appeared to have
more loss than the 250 Hz one (it should be the other way around).
Talking with another K3 owner brought the possibility that the 400 Hz
filter might need an offset, so I fed my signal generator into the K3
and checked. Adjusting the offset brought up the signal by 1 S-Unit to
match the reading from the 250 Hz filter, I set the offset in the middle
of the two points where the meter dropped. The optimum setting for my
filter is -0.07.

I think this has been discussed here before (possibly by Tom, N0SS) but
I couldn't find it during a search.

My 400 Hz filter was supplied with my K3 in Nov 2007, the 250 Hz filter
was new this year.

73 Dave, G4AON
K3/100 #80
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[N5GE]

On Sat, 17 Oct 2009 12:37:31 +0100, Dave G4AON
<[hidden email]> wrote:

>Since obtaining an 8 pole 250 Hz filter to compliment my 8 pole 400 Hz
>filter, I have been puzzled as to why the 400 Hz filter appeared to have
>more loss than the 250 Hz one (it should be the other way around).
>Talking with another K3 owner brought the possibility that the 400 Hz
>filter might need an offset, so I fed my signal generator into the K3
>and checked. Adjusting the offset brought up the signal by 1 S-Unit to
>match the reading from the 250 Hz filter, I set the offset in the middle
>of the two points where the meter dropped. The optimum setting for my
>filter is -0.07.
>
>I think this has been discussed here before (possibly by Tom, N0SS) but
>I couldn't find it during a search.
>
>My 400 Hz filter was supplied with my K3 in Nov 2007, the 250 Hz filter
>was new this year.
>
>73 Dave, G4AON
>K3/100 #80

[snip]

I found this to be true of my 400Hz and 250Hz filters also.  

If you also have a sub RX it will help get the two to be exactly
together by doing the same to net the filters in the SUB with main.

Tom, N5GE

[hidden email]
K3 #806, K3 #1055, PR6,
XV144, XV432, KRC2,
W1 and other small kits.

2 W2's on order
1 K144XV on order

http://www.n5ge.com
http://www.swotrc.net


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[Laurent F6DEX]

Hello

I found an offset of 0.05 KHz with the 400Hz filter.

Laurent