[Elecraft] K3s 400 Hz filter differences...

[Clay Autery]

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
(318) 518-1389