[Elecraft] panadapter "noise" without antenna connected

[Guy Olinger K2AV]

Before the antenna is connected, the input is unterminated. When that is
true the internal noise is anywhere from 20 to 40 dB higher.  If you want
to view the true level of the internal noise, connect the input of the P3
to a 50 ohm termination.

Seeing internal noise on an unterminated high impedance input is not an
equipment malfunction, it's usual.

73, Guy K2AV

On Tue, Oct 14, 2014 at 9:35 AM, <jsdroyster at nc.rr.com> wrote:

> Greetings from KT4JR and K4MWE to you smart folks...
>
> Our panadapter regularly (but not always) shows wide green bands of
> "noise" before the antenna is connected.  When present, the bands are
> visible in the same panadapter screen location regardless of wbich band the
> radio is turned to, but the locations vary day to day (sometimes at the low
> end of the screen, other times in the middle).  The white line on the
> screen rises to peaks above these green areas.
>
> How would we figure out what the source of this is?  It is present when no
> other appliances are being used in our house, so it is not our own AC,
> dishwasher, etc.
>
> THANKS for suggestions!
> 73,
> KT4JR
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k2av.guy at gmail.com
>