External LPF

[pu2clr]

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?

[AE9RB]

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.

[pu2clr]

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.

73,
PU2CLR.