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[TenTec] Re: inrad filters

To: <tentec@contesting.com>
Subject: [TenTec] Re: inrad filters
From: w5yr@att.net (George, W5YR)
Date: Tue Apr 15 13:48:40 2003
Thanks, Tim, but you know that I would never say anything about that radio
here!   <:}

No, the center frequency is a term which usually denotes the frequency about
which the passband is of the filter is symmetrical or nearly so. It
literally is the center frequency of the passband.

I am unfamiliar with the INRAD filter line although I hear a lot of good
things about them. I would guess that there are some radios which have their
insertion oscillators set such that a center frequency of 9000.6 KHz works
better in some sense than one of 9000.7, and vice versa.

Usually this is not much of a consideration with narrow CW filters, since
you can vary the insertion frequency to provide for CW pitch control. Again,
on the IF DSP radios, the IF DSP filters for CW are generated to be centered
on the CW pitch frequency you have selected, and the receiver tuning is
always offset from the received signal to produce exactly that beatnote.

The Handbook used to have some neat diagrams of filter responses showing how
the carrier insertion oscillator frequency was placed relative to the
passband, etc.

73/72, George
Amateur Radio W5YR -  the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"

----- Original Message -----
From: <tlogan7@cox.net>
To: <tentec@contesting.com>; <tentec@contesting.com>; "Mike J Maloney"
Cc: <tentec@contesting.com>
Sent: Tuesday, April 15, 2003 12:29 PM
Subject: Re: Re: [TenTec] Re: inrad filters

> George -
> Thank you. Is the insertion frequency the same thing as the center
frequency? In my original question I mentioned that there were TWO Inrad
400Hz filters - one with a 9000.6 center freq - and the other with 9000.7. I
completely understood your note, but I do not know if the center freq is the
same as insertion freq. PS - you sly dog - had to slip in a mention of one
of the benefits lost when I sold the PRO II hi hi! As always, thanks
George - much appreciated!
> Regards, Tim

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