Posted by
Alan Bloom on
Apr 25, 2011; 2:10am
URL: http://elecraft.85.s1.nabble.com/Info-on-K3-IF-OUT-tp6299452p6301890.html
I'm not familiar with a "Winloe" detector. I assume you are using some
kind of quadrature downconverter, such as LP-PAN, to convert the K3's
8.215 MHz IF to an I/Q baseband signal to feed to the stereo input of a
sound card connected to a personal computer. In that case, the IF
bandwidth should be somewhat less than the sample rate of the sound
card.
With a typical 192 ksps sound card, you should get 180 kHz or so
bandwidth.
If you're only getting 44 kHz RF bandwidth, that sounds like the sample
rate may be only 48 kHz. Your 192 ksps sound card may have accidentally
been set to 48 kHz. I would read your sound card documentation to
figure out how to check for that.
BTW, the P3 works differently. It samples the IF directly at a high
rate (60 MHz) and does the quadrature downconversion digitally. The
advantage is much greater accuracy (for example, no "images" on the
other side of the center frequency) and the ability to work with
different IF frequencies without any change to the hardware.
Alan N1AL
On Sat, 2011-04-23 at 12:10 -0400, John Ragle wrote:
> In part, my reason for asking is the following...
>
> I am feeding the K3 IF Out into a fast ADC at 192 kHz, followed by a
> Winloe detector, etc. for panoramic viewing, but despite the 192 kHz
> sampling frequency I am only getting about 44 kHz TOTAL spectral width.
> Thus, there seems to be a front-end bandwidth of about +/- ~25 kHz. Is
> this true? Or am I doing something wrong?
>
> The P3 comes up with a TOTAL spectral width of ~200 kHz. Where does it
> pick its signal from?
>
> John Ragle -- W1ZI
>
> =====
>
> On 4/23/2011 11:44 AM,
[hidden email] wrote:
> > It is a wideband, low-level signal. The bandwidth is just limited by the
> > front-end filters in the K3. The level is about 7 dB less than the level
> > at the K3 antenna input (preamp and attenuator off). On older K3s that
> > don't have the IF OUT modification the level is less than that, by about
> > 8-10 dB as I recall.
> >
> > Alan N1AL
> >
> >
> >> Aside from the frequency, I can find nothing about the characteristics
> >> of the K3 "IF OUT" feed. Could some kind person provide info about
> >> bandwidth, levels, etc...?
> >>
> >> John Ragle -- W1ZI
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