[Elecraft] Question about filters in USB as shown on a P3

[Tom]

Thanks, got it
73s Tom




-------- Original message --------
From: "Joe Subich, W4TV" <lists at subich.com> 
Date: 02/11/2013  16:42  (GMT-05:00) 
To: elecraft at mailman.qth.net 
Subject: Re: [Elecraft] Question about filters in USB as shown on a P3 
 

The P3 display shows the "carrier (dial) frequency" as a vertical line
and the audio (filter) bandwidth as the boarder bar.  In USB/LSB the
filter bandwidth is typically something like 200 Hz to 2900 Hz (for
a 2.7 KHz "width").

If you have selected shift/width instead of Lo/Hi, adjusting "width"
will reduce the bandwidth equally above and below the center frequency
(typically 1500 Hz).  Thus if you select "width" = 2.1 KHz the filter
will be 500 - 2600 Hz and you will see 500 Hz between the vertical
line (carrier/dial) and the actual filter response.

73,

    ... Joe, W4TV


On 11/2/2013 4:28 PM, tomb18 at videotron.ca wrote:
> Hi,
>
> I have a question concerning what you see on the P3 when you tune in a USB signal.
> The green band that represents the bandwidth is not quite at the tuned in frequency (center frequency) but is displaced slight higher in frequency. If you lower the bandwidth say using a 2.1 KHz filter it has shifted quite a bit up.
> Can someone explain what is happening from the radio point of view please?
>
> Thanks, Tom VA2FSQ
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