K3s 400 Hz filter differences...

[Clay Autery-2]

The 400Hz filter on my Main RX is an Elecraft (by INRAD) 8-pole filter
in a Faraday cage and no offset.
The 400Hz filter I just received for my SubRX  is an Elecraft (by
Vibroplex?) that is a 6-pole filter with no Farady cage AND it has a
-0.71 kHz offset.

I called support when I saw the obvious differences, and they said,
"Don't worry about it.  Enter the SubRX offset exactly as on the crystal
(no averaging with the [supposed] 0.00 offset on the 8-pole filter), and
let the new Synthesizers do the heavy lifting." or words to that effect.

I hear what was said, and I don't want to come off like I don't trust
what I was told....  But something simply is not sitting right with me
on this.... a 6-pole "matched" with an 8-pole?  No offset averaging? 
What about the difference in the skirts between a 6-pole and an
8-pole.... Aren't the cutoffs and cutoff rates different?  I realize
that things change, and that perhaps the instructions for averaging the
offsets is not applicable here... (though I don't yet understand why)

Can someone clear this up for me so even I can understand it.

Seems to me that I either need to get a matching INRAD-made 8-pole, or
buy another of these new parts and try to get it matched.

Want to move on this, because IF I am going to have a hope in getting a
"matching" 6-pole (new stock) 400 Hz filter, I need to try and do so
from within the same batch that the one I just bought came from.
The prospect of finding an "by INRAD" 8-pole available on the market
seems much less likely...

Obviously, I am operating on a number of assumptions here... which is
why I am asking...


73

______________________
Clay Autery, KY5G
[phone]

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[Nr4c]

I think you’ll find in the release notes that main/sub filters no longer need to be matched.  

However, I think I’d be happier with two alike, either 2 8-poles or 2 6-poles.

Sent from my iPhone
...nr4c. bill

> On Jan 14, 2020, at 7:18 AM, Clay Autery <[hidden email]> wrote:
>
> The 400Hz filter on my Main RX is an Elecraft (by INRAD) 8-pole filter in a Faraday cage and no offset.
> The 400Hz filter I just received for my SubRX  is an Elecraft (by Vibroplex?) that is a 6-pole filter with no Farady cage AND it has a -0.71 kHz offset.
>
> I called support when I saw the obvious differences, and they said, "Don't worry about it.  Enter the SubRX offset exactly as on the crystal (no averaging with the [supposed] 0.00 offset on the 8-pole filter), and let the new Synthesizers do the heavy lifting." or words to that effect.
>
> I hear what was said, and I don't want to come off like I don't trust what I was told....  But something simply is not sitting right with me on this.... a 6-pole "matched" with an 8-pole?  No offset averaging?  What about the difference in the skirts between a 6-pole and an 8-pole.... Aren't the cutoffs and cutoff rates different?  I realize that things change, and that perhaps the instructions for averaging the offsets is not applicable here... (though I don't yet understand why)
>
> Can someone clear this up for me so even I can understand it.
>
> Seems to me that I either need to get a matching INRAD-made 8-pole, or buy another of these new parts and try to get it matched.
>
> Want to move on this, because IF I am going to have a hope in getting a "matching" 6-pole (new stock) 400 Hz filter, I need to try and do so from within the same batch that the one I just bought came from.
> The prospect of finding an "by INRAD" 8-pole available on the market seems much less likely...
>
> Obviously, I am operating on a number of assumptions here... which is why I am asking...
>
>
> 73
>
> ______________________
> Clay Autery, KY5G
> [phone]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
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[ab2tc]

Hi Clay,

I have a 5-pole filter with -0.85kHz offset according to the label on it.
It's yours for the asking if it's any good to you. It was working when I
removed it a number of years ago.

AB2TC - Knut


Clay Autery-2 wrote
> The 400Hz filter on my Main RX is an Elecraft (by INRAD) 8-pole filter
> in a Faraday cage and no offset.
> The 400Hz filter I just received for my SubRX  is an Elecraft (by
> Vibroplex?) that is a 6-pole filter with no Farady cage AND it has a
> -0.71 kHz offset.
>
> I called support when I saw the obvious differences, and they said,
>  
> <snip>





--
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[Clay Autery-2]

Yep... here it is right here, wayyyy back on v5.33:

/** DIVERSITY WORKS WITH MISMATCHED MAIN/SUB RX FILTERS: Diversity mode
in the K3S (or a K3 with the KSYN3A installed) now works with any
combination of main/sub RX crystal filters. They can have different
bandwidths or offsets, and it's not necessary to have an equal number of
filters in each receiver. Note: Matched filters are optimal for
diversity, but non-matched filters will still perform well.*//*
*/

"Matched filters are optimal...."

End of discussion as to IF I will get matched filters....  Now to decide
between the "in-house" 6-pole I just bought, or an INRAD #701 that
matches the one I bought with my MAIN Receiver...

73,

______________________
Clay Autery, KY5G
[phone]

On 01/14/20 11:16, Nr4c wrote:

> I think you’ll find in the release notes that main/sub filters no longer need to be matched.
>
> However, I think I’d be happier with two alike, either 2 8-poles or 2 6-poles.
>
> Sent from my iPhone
> ...nr4c. bill
>
>
>> On Jan 14, 2020, at 7:18 AM, Clay Autery <[hidden email]> wrote:
>>
>> The 400Hz filter on my Main RX is an Elecraft (by INRAD) 8-pole filter in a Faraday cage and no offset.
>> The 400Hz filter I just received for my SubRX  is an Elecraft (by Vibroplex?) that is a 6-pole filter with no Farady cage AND it has a -0.71 kHz offset.
>>
>> I called support when I saw the obvious differences, and they said, "Don't worry about it.  Enter the SubRX offset exactly as on the crystal (no averaging with the [supposed] 0.00 offset on the 8-pole filter), and let the new Synthesizers do the heavy lifting." or words to that effect.
>>
>> I hear what was said, and I don't want to come off like I don't trust what I was told....  But something simply is not sitting right with me on this.... a 6-pole "matched" with an 8-pole?  No offset averaging?  What about the difference in the skirts between a 6-pole and an 8-pole.... Aren't the cutoffs and cutoff rates different?  I realize that things change, and that perhaps the instructions for averaging the offsets is not applicable here... (though I don't yet understand why)
>>
>> Can someone clear this up for me so even I can understand it.
>>
>> Seems to me that I either need to get a matching INRAD-made 8-pole, or buy another of these new parts and try to get it matched.
>>
>> Want to move on this, because IF I am going to have a hope in getting a "matching" 6-pole (new stock) 400 Hz filter, I need to try and do so from within the same batch that the one I just bought came from.
>> The prospect of finding an "by INRAD" 8-pole available on the market seems much less likely...
>>
>> Obviously, I am operating on a number of assumptions here... which is why I am asking...
>>
>>
>> 73
>>
>> ______________________
>> Clay Autery, KY5G
>> [phone]

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