[RFI] 160m-5mhz noise?

Sam Morgan k5oai.sam at gmail.com
Fri Nov 6 04:43:13 PST 2009

Paul Christensen wrote:

> I have come to rely on 
> one indispensable tool to locate these noise sources:  A Palomar LA-1 loop 
> antenna.  The tropical band plug-in loop covers the lower bands through 6 
> MHz with razor-sharp directivity.

> Another tool I use with the LA-1 is an SDR-IQ receiver connected to my 
> netbook PC and Elecraft K3's I.F. port.  The SDR-IQ functions as a spectrum 
> analyzer on the netbook PC -- and its powered by the netbook USB port.  A 
> 14.4VDC gel cel powers the K3.  I just throw it all into a Klein 
> electricians bag and start roaming on foot. >
I have a K2 and a softrock sdr, perhaps I can borrow a laptop.....

> In addition to a rise in noise floor, you'll often see switching peaks every 
> 30 kHz to perhaps 100 kHz, depending on the switching frequency of the 
> source.
that is why I ask the group about this noise, I am familiar with the normal 
'every so many kc' type switching supply noise. But this solid noise floor, 
noise, is something new to me. I wasn't relating it to a switching supply as it 
didn't either sound like what I am use to, nor had the every so many kc 

> No doubt a high-quality loop antenna can be home-brewed.  However, I have so 
> many projects in the fire that I need to know when to just order something 
> and the LA-1 has been an absolute blessing.  However, the LA-1 is no longer 
> made by Palomar.  But the good news is that Palstar makes a near-identical 
> unit.
> http://www.palstar.com/la30.php
> The schematics are identical to the LA-1, but with a few improvements.  I 
> just purchased their version of the tropical loop antenna since it resonates 
> to 7500 kHz.  I have a new switch mode noise source only on 40m that the 
> LA-1 loop cannot tune since it stops resonating at 6000 kHz.  So, I am 
> hopeful the Palstar loop will stay part of my RFI/EMI detection kit.

wow, I might could afford the tropical loop antenna,
but the $300+ unit it works on is certainly out of my price range, oh well.

GB & 73
Sam Morgan

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