External LPF

General discussion and support for the Peaberry SDR V1.

External LPF

Postby pu2clr » Fri Dec 14, 2012 8:23 pm

I am using a Magnetic Loop Antenna.
In this case, Is the LPF necessary?
The magnetic loop antenna has a high “Q”. So the band width is very narrow.
Am I right?
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Joined: Sat Nov 24, 2012 2:32 am

Re: External LPF

Postby AE9RB » Fri Dec 14, 2012 9:12 pm

The Peaberry filters are designed to meet spurious emission rules. You can hook up a spectrum analyzer and prove this to yourself and the FCC.

It's true that your magnetic loop will do some filtering of spurious emissions. The problem is how to prove it. I don't know how. Also, can you ensure no spurious emissions while you're tuning the loop? A LPF can.

My recommendation is to always use the proper LPF. Of course, this is amateur radio so you're entitled to experiment with other ideas if you have the expertise.
73 David AE9RB
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Re: External LPF

Postby pu2clr » Sat Dec 15, 2012 6:04 pm

Ok. I understood.
I asked you about it because I built a Automatic Antenna Tuner controlled by Arduino for my Magnetic Loop.
For while I can control it using a Android Device.
My Idea is control my Antenna Tuner also via a modified version of a SDR program. So, instead tuning my Magnetic Loop Antena using a SWR meter,
I intent do that via receiving signal lavel.
In this case, I start transmitting after the system is coupled.

If you wish, you can see my Antenna Tuner working in my Youtube Channel (PU2CLR). Direct link: http://youtu.be/cZjbZRGTyVc

Thanks for your answer. It was very enlightening.

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Joined: Sat Nov 24, 2012 2:32 am

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