Like other roofing filters, the narrower the passband, the more loss.
In general the loss is similar to those shown for the FT-1000 8.215 MHz
filters shown on the INRAD web site. Our 5 pole filters in some cases
have a little less loss.
The loss at this point in the radio (the first I.F.) has very little
impact on MDS or other characteristics, because the noise figure is
established in earlier stages.
When you install any roofing filter, you use the menu to tell the
firmware what the filter's bandwidth is, any small offset from 8.215
MHz, and what the relative loss of the filter is. The DSP adjusts the
15-kHz I.F. gain based on the entered loss amount, so all filters have
the same overall gain.
Once a filter is installed, you can specify which modes it is available
in (or all modes).
73,
Wayne
N6KR
On Apr 29, 2007, at 3:57 AM, DOUGLAS ZWIEBEL wrote:
Can you discuss the loss of the "narrow" roofing filters and elaborate
on "how" you compensate for that? How does that compensation impact
rx peformance specs (ie, do some "get worse)?
Thanks,
de Doug KR2Q
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