The roofing filter is the 1st IF filter, and determines the absolute widest
bandwidth which can be received. There are 4 IFs in the Mark V. The stock
roofing filter in the radio is 15 Khz, a 70 Mhz filter. The 4th IF is
entirely digital, and is the location of the DSP circuitry.
The selectable filters are found in the 2nd and 3rd IF stages, and are
normally crystal or mechanical filters.
The Inrad roofing filter is a crystal filter. The stock filter I believe is
ceramic. The Inrad mod places the two filters in series with a low noise
amplifier to make up for insertion losses.
73 and Happy DXing,
Mike
W2AJI
----- Original Message -----
From: "Keith Dutson" <kdutson@sbcglobal.net>
To: "Yaesu List" <yaesu@contesting.com>
Sent: Friday, July 21, 2006 12:58 PM
Subject: Re: [Yaesu] FW: roofing filters
> It is actually a part of the first mixer.
>
> Keith
>
> -----Original Message-----
> From: Paul Manuel [mailto:k4pdm@yahoo.com]
> Sent: Friday, July 21, 2006 11:36 AM
> To: Keith Dutson
> Subject: Re: [Yaesu] FW: roofing filters
>
>
>
> --- Keith Dutson <kdutson@sbcglobal.net> wrote:
> > I believe the new term was first used when the filter in front of the
> > IF string became selectable. The filters you are speaking of are IN
> > the IF string.
>
> So there is a switchable filter that works at the actual received
frequency,
> before frequency conversion to an IF? Now I am really confused!
> 73,
> Paul K4PDM
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
> _______________________________________________
> Yaesu mailing list
> Yaesu@contesting.com
> http://lists.contesting.com/mailman/listinfo/yaesu
_______________________________________________
Yaesu mailing list
Yaesu@contesting.com
http://lists.contesting.com/mailman/listinfo/yaesu
|