K3: Receiving 4th Harmonic of AM Station

[Jay-86]

The local AM station on 940 is wiping out my K3 on 1880 and 3760 to the
tune of 20-30db over.  Have the same problem with just the sub
receiver.  Plugged in my K2 and FT-900 and don't have the problem.  Any
ideas other the bench the K3 :-)


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[Ken Kopp-3]

Harmonics from BC stations are not uncommon.
Those of us who haunt 160M are familiar with them.

In your case, the question is how strong they actually
are, and does the station meet it's FCC specified
specs?  Often, the "engineer" ... if the station actually
has one in residence ... probably is unaware of any
harmonic(s) ... and in reality, doesn't care.

Today, many / most stations have an engineer on
call for when they need one, and he / she's often
hundreds of miles away.

I have a 1KW on 570 kHz three miles away and it's
not a problem.  

Tell us more...

73! Ken Kopp - K0PP
       [hidden email]


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[Jim Brown-10]

On Fri, 23 Jul 2010 10:37:46 -0700, Jay wrote:

>The local AM station on 940 is wiping out my K3 on 1880 and 3760 to the
>tune of 20-30db over.

I'd bet that you have preamp on and the attenuator off, so you're probably
overloading the K3. Turn on the attenuator and turn off the preamp. That
should fix it.

73, Jim K9YC


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[Jack Smith-6]

Sounds like an application for a high pass filter. That strong a signal,
and that it is not being detected by other receivers, certainly sounds
as if it is being generated in the K3 due to overload.

There are 100 watt transmit power level AM broadcast band high pass
filters available that can easily be installed.

Jack


On 7/23/2010 1:37 PM, Jay wrote:

> The local AM station on 940 is wiping out my K3 on 1880 and 3760 to the
> tune of 20-30db over.  Have the same problem with just the sub
> receiver.  Plugged in my K2 and FT-900 and don't have the problem.  Any
> ideas other the bench the K3 :-)
>
>
> ______________________________________________________________
> 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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