[Premium-Rx] Roofing Filter Question

[Carcia, Frank A. HS]

Hi,
Racal used two roofing filters to help the dynamic range in close. The
MC1496 second mixer is the weak link in the chain. the tighter skirts and
deeper ultimate rejection improves the close in performance. The 8 kHz
filters were used in the VLF configuration but also help at H.F. as long as
you can live with the 8 KHz bandwidth. I have a pair of them in my RA6830
hot rod.  fc

-----Original Message-----
From: Chuck Hutton [mailto:charlesh3 at msn.com]
Sent: Wednesday, March 24, 2004 10:53 PM
To: premium-rx at ml.skirrow.org
Subject: RE: [Premium-Rx] Roofing Filter Question


Guy:

I would put the narrow filter first. Its selectivity would reduce (somewhat)
the signal level at every stage past it by eliminating some adjacent
signals, and therefore improve the strong signal handling a bit.

I don't know the 6790 - why does it have two roofing filters at the same
frequency?


Chuck

-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Guy Atkins
Sent: Wednesday, March 24, 2004 4:28 PM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] Roofing Filter Question




I'm replacing one of two 20-kHz, 40.455 MHz roofing filters in the first
I.F. of a RA6790GM with a 10 kHz version for hopefully better dynamic range
on mediumwave.

Should the narrower 10 kHz filter be first in the signal path, or instead be
the 2nd roofing filter in the chain for best performance?

Thanks,

Guy Atkins
Puyallup, WA USA



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