Confusion on Roofing Filters

[w0ih]

I'm a bit confused on the specifications of the roofing filters on the KX3.  Will there be a roofing filter that is standard with the KX3, like the K3, or are you required to buy at least one as an option?

Are the roofing filters in the same format as for the K3, or is it a different setup?

Mike

[wayne burdick]

Mike, w0ih wrote:

> I'm a bit confused on the specifications of the roofing filters on  
> the KX3.
> Will there be a roofing filter that is standard...?

The KX3's direct-conversion/quadrature (I/Q) receiver works with or  
without roofing filters. You could certainly start with the basic unit  
and add the roofing filter module later, if necessary, for your  
operating conditions.

In fact, the KX3 is the only transceiver of this type that we know of  
that even offers a balanced roofing filter in the receive I/Q path.  
It's been a challenge, but we the results will be worth it. Adding  
this module makes the KX3's receiver perform more like a superhet,  
with better blocking and IMD dynamic range. But it will retaining the  
advantages of I/Q demodulation, including very flat passband response,  
fewer mixing spurs, no-tune RF filtering, and the ability to use SDR  
(software-defined-radio) applications.

We'll clarify all this when we update the KX3 brochure.

73,
Wayne

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[w0ih]

Wayne,

Thanks for the very prompt reply last week to my query.

So now I have another question concerning roofing filters.  Will the KX3 use the same roofing filter series as the K3?  

I added a 2.1 kHz filter in my K3 and found it very effective (after a bit of learning!).  Since then, I've wanted to upgrade the 5 pole filter that I have in my K3 to an 8 pole.   Can I put the 5 pole that I pull from the K3 into the KX3?

Mike

[KK7P]

No, the KX3 uses a completely different architecture than the K3.

73,

Lyle KK7P

> ...Will the KX3 use the same roofing filter series as the K3?

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[wayne burdick]

Hi Mike,

The KX3 converts RF directly to baseband, so the roofing filters are  
made using high-performance op-amps and very tight-tolerance discrete  
parts, not crystals.

73,
Wayne
N6KR


On Sep 6, 2011, at 2:06 PM, w0ih wrote:

> Wayne,
>
> Thanks for the very prompt reply last week to my query.
>
> So now I have another question concerning roofing filters.  Will the  
> KX3 use
> the same roofing filter series as the K3?
>
> I added a 2.1 kHz filter in my K3 and found it very effective (after  
> a bit
> of learning!).  Since then, I've wanted to upgrade the 5 pole filter  
> that I
> have in my K3 to an 8 pole.   Can I put the 5 pole that I pull from  
> the K3
> into the KX3?
>
> Mike
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Confusion-on-Roofing-Filters-tp6708928p6765692.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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