[Elecraft] P3 Broad Birdie

[Jim Brown]

We're talking about two different things. There are birdies generated 
within the K3 that show up in the P3 as signals, and that move around as 
you tune.  This is a problem within the K3.

Noise and unstable birdies that drift in  frequency (usually, but not 
always, very slowly) is RF trash produced by all forms of electronic 
equipment, but mostly switching power supplies (including those for 
battery chargers, etc.). This stuff is radiated by the wiring connected 
to the noisy equipment, and is picked up by our antennas, just like any 
other radio signal.

The P3 can be a VERY useful tool for chasing the sources of this trash, 
because it lets us see it more clearly.  Some of these noise sources 
have a carrier frequency, but most of them are frequency modulated by 
random noise so that you don't hear a carrier. This modulation is called 
"dither", and serves to skirt FCC regulations which limit the field 
strength at a single frequency.  So instead of seeing (and hearing) a 
strong carrier, you see (and hear) a broad hump of noise.  The result is 
that the noise level is raised within the width of that hump, typically 
several kHz (or tens of kHz on VHF).

73, Jim Brown K9YC

On 6/12/2011 12:14 PM, John Ragle wrote:
> I see it on both the K3 and the P3 but it does not interfere with
> operation, as I am mostly narrow band, with the P3 span stopped down as
> well. It is ~10 dB tall on the P3. A component of it meanders around the
> PSK regions on 20, 15, and on 6 and much less on 2. It is something in
> the house or the neighborhood, perhaps a plasma TV. It is present all
> the time that I am awake.
>
> =====
>
> On 6/12/2011 2:40 PM, Dave Perry wrote:
>> Yes, I get the wide birdie all the time on the P3, but I also hear it on the
>> K3.  I always figured it was something in the house.
>>
>> Dave, N4QS
>>
>>
>> ----- Original Message -----
>> From: "Phil Theis"<phil at k3tuf.com>
>> To:<elecraft at mailman.qth.net>
>> Sent: Saturday, June 11, 2011 7:45 PM
>> Subject: [Elecraft] P3 Broad Birdie
>>> Does anyone else get the wide birdie that floats around the P3 screen?
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