[R-390] More USB & LSB Filters

[John Kolb]

On Wed, 24 Dec 2003, Dallas Lankford wrote:

> I forgot to mention that I don't know where I got the 526 9365 000 and
> ...65 000 filters.  I also have a pair of 526 9364 061 and ...65 061.
> They seem to be the same filter, except perhaps for a bit wider
> bandwidth.  That doesn't matter if you use a 6 kHz roofing filter like I
> do.  I believe I got the ...061's from Surplus Sales Of Nebraska several
> years ago for $100 each.

It's hard to find accurate information on mechanical filters.
The 1976 Collins Mechanical Filter Catalog lists the 526 9364 000
as a F455Z-1, USB 2.7 kHz @ 3db Y(long) case, and the 526 6365 000
as a F455Z-5, LSB 2.7 kHz @ 3db Y(long) case. A filter list
I picked up somewhere along the way lists the 526-9364-000
and 65-000 as 3.0 @ 6 db and 6.0 @ 60 db and the 64-061 and 65-061
as 3.40 @ 6 and 7.55 @ 60. 2.7 min at 3 db and 3.0 @ 6 db could
both be accurate descriptions ofthe same filter, measured at
different points on the filter nose.

The labels on the 64-000 and 65-000 in Dallas's modification
article list a BW of 3.4 kHz on the label, but the label from
what I can see of it, doesn't look like an offical Collins label.

Note that filter specifications are listed as a minimum BW at the
top of the curve and maximum at the bottom. They can be quite
a bit wider at the top and narrower at the bottom. My favorite
filter, the F455Z23C, is spec'ed as 2. 85 kHz @ 3 db min, 3.1 kHz
nominal, and 4.9 kHz max 4.1 nominal. One example I have run curves
on <http://members.cts.com/king/j/jlkolb/site/curves/F455Z232.PDF>
is 3.50 kHz @ 3 db, 4.84 kHz @ 60. Considerably wider than one
would expect from the published specs.

John
<http://members.cts.com/king/j/jlkolb>