Inrad vs icom.
Dels är det ju på pappret skillnad på värden, dämpningen är 9 db på inrad och 6 db på icom.
Shape factor på inrad 1.8, icom 1.9, jag upplevde att inrad filtret hade mer brantare flanker vilket kändes mer "exaktare".
Dämpningen gjorde också att signalen hördes tydligare, skillnaden var minimal men det kan göra skillnad på ett supersvagt dx.
Hur var och en upplever detta blir en personlig uppfattning fast då många "senior amatörer" har lite sämre hörsel kan det upplevas som "skit samma", inrad filtren är billigare än icom och då tycker jag att man får "mer" prestanda för pengen, dock en egen uppfattning.
Bifogar lite mer info från arrl.
What's the difference between IF filters from Inrad vs. Icom?
Inrad filters tend to have a superior shape factor to
Icom's (smaller numbers are better) as well as deeper
stopbands. They also tend to be cheaper.
When dealing with adjacent channel interference, the
filter shape (depth and slope of the attenuation curve)
is generally the prime factor. Inrad filters tend to
outperform the Icom filters for this application.
For example. The stock Icom filter in the 455Khz IF
has a -6db bandwidth of 2.4Khz and a -60db bandwidth of
about 5Khz. That gives it a shape factor of about 2.1
The comparable filter from Inrad has a shape factor of
1.6, a -6db bandwidth of 2.4Khz and a -60db bandwidth
of 3.8Khz.
This all means that the Inrad filter has a steeper
attenuation curve, resulting in better extraneous signal
rejection and improved selectivity.
The Inrad filters tend to have greater ultimate
attenuation than the Icom counterparts. Thus, Inrad
filters tend to do a better job of adjacent signal
rejection than Icom's filters.
However, while the 455Khz Inrad filters are drop-in
replacements for the Icom counterparts, the 9Mhz filters
are not. They need a short piece of coax and a connector
to wired up to the filter first. The adapting connector
plugs into the filter slot, thus alleviating any mods
to the radio itself. Reported assembly times range
from 1-4 hours per filter, depending upon the skill
and care of the installer.
Finally, some claim that there is an insertion loss
to the Inrad filters vs. the Icom filters. However,
it's been demonstrated that dropping the noise level
also drops the S-meter reading, possibly accounting for
the reports. Bench tests do not show any insertion loss.
Your ears may vary.
eHam.net has several user reviews on Inrad crystal
filters at:
International Radio (Inrad) Crystal Filters Product Reviews