[Premium-Rx] Roofing Filter Question

[Guy Atkins]

Hi Todd,

I found a couple of distributors/manufacturers on the web, but neither of
them replied to my inquiries. They probably don't deal with hobbyist-sized
orders.

The 10 kHz, 40.455 MHz filter I'm going to be using was part of a Cubic
receiver IF module. I wish it was an 8 kHz bandwidth, but 10 kHz is
certainly better than 20 for my purposes. Now I hope to find another 8 or 10
kHz filter somewhere.

You might try calling the surplus outlets like Murphys or Toronto Surplus to
see if they have any floating around.

Guy



 -----Original Message-----
From: ToddRoberts2001 at aol.com [mailto:ToddRoberts2001 at aol.com]
Sent: Thursday, March 25, 2004 8:09 AM
To: dx at guyatkins.com
Subject: Re: [Premium-Rx] Roofing Filter Question


  In a message dated 3/24/2004 7:28:26 PM Eastern Standard Time,
dx at guyatkins.com writes:
    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
  Hi Guy, I saw your posting about replacing one of the roofing filters in a
Racal RA6790/GM with a 10KHz wide filter. I was wondering do you have a
source for these filters? I am in the process of converting a 6790 to the
VLF version. As Frank Carcia has mentioned one of the changes Racal made to
the VLF version was using an 8KHz roofing filter in board A3 versus the
original 20KHz wide filters. I believe this was to allow the receiver to
tune down to around 10KHz or so and avoid the local oscillator from bleeding
thru. If those filters are available I would like to try one out myself.
Thanks, yours truly, Todd Roberts WD4NGG.
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