> Is either one/both wide enough for 500Hz Olivia modes?
I would question using either 500 Hz option for Olivia since the
group delay will be significant in the shoulder areas and that
can impact the "outer" tones considerably.
> Any thoughts on the merits of one vs the other?
My Elecraft 500 Hz, 5-pole filters averaged 480 Hz at the -6dB
points while the INRAD filters tend to be about 10% (or more)
wider than nominal, particularly as the nominal bandwidth
decreases. On the other hand, the skirts are much sharper (better
shape factor) with the 8 pole filters.
> does the 8-pole Inrad filter not need to be matched?
There is no "matching" for the INRAD filters but their center
frequencies are not well controlled. In a recent sample of
four 400Hz INRAD filters, I measured offsets at -15 Hz, +24 Hz,
+45 Hz and + 55 Hz. The total difference of 60 Hz in 430 Hz
(average) measured bandwidth is a bit concerning. I ended up
with the -15 Hz/+24 Hz pair in one rig (no offset) and the
+45 Hz/+55 Hz pair in the other rig with a slight offset to
center the pair.
73,
... Joe, W4TV
On 1/25/2011 9:27 AM, Ross Primrose wrote:
> Any thoughts on the merits of one vs the other? The 5-pole filter is
> cheaper, but they need to me matched for diversity receive, does the
> 8-pole Inrad filter not need to be matched? Is either one/both wide
> enough for 500Hz Olivia modes?
>
> Thanks...
>
> 73, Ross N4RP
>
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