[ARC5] FCC General exam

[Geoff]

With low noise receiving antennas then the noise is quite low. In the 
153-279 KHz BC band I have logged many stations over the years including 
some very seldom heard in the US. Day to day propgation can cause 30-40 dB 
difference in signal but the intended audiences receive it via ground wave 
at powers up to 2 MW.

Carl


----- Original Message ----- 
From: D C _Mac_ Macdonald
To: Bruce Long ; KM1H Carl H. ; ARC-5 Mail List
Sent: Tuesday, November 26, 2013 2:02 PM
Subject: RE: [ARC5] FCC General exam


Theoretically a maybe, but practically speaking, how much signal will be 
heard amidst all the atmospheric noise at 100 kHz?  Well, I admit I don't 
have a RX to listen there.

* * * * * * * * * * *
* 73 - Mac, K2GKK/5 *
* (Since 30 Nov 53) *
* k2gkk hotmail com *
* Oklahoma City, OK *
* USAF & FAA (Ret.) *
* * * * * * * * * * *


> Date: Tue, 26 Nov 2013 10:51:02 -0800
> From: coolbrucelong at yahoo.com
> To: geoffrey at jeremy.mv.com; k2gkk at hotmail.com; arc5 at mailman.qth.net
> Subject: Re: [ARC5] FCC General exam
>
> a long long time ago when I was a novice there was an uproar about a FCC 
> propagation question.  The question was "What frequency is most reliable 
> for long range communications?  Most hams would of course answer 14 MHz 
> which is arguably the correct answer for the amateur service  but the 
> "Correct" answer was 100 kHz because of ground wave propagation which is 
> global in extent and largely unaffected by the state of the ionosphere.
>
>
> On Monday, November 25, 2013 8:47 PM, Geoff <geoffrey at jeremy.mv.com> 
> wrote:
>
> Yep, I still say sunset at least at one end of the path is the real answer
> that most mainstream academics totally miss and gives the very long 
> distance
> grayline propagation which extends from MF to at least 10M.
>
> Low band DXers work anywhere on the planet at their sunset or sunrise (I
> have close to 300 DXCC countries on 160 and a lot more on 80 and 40.
> And it is rather amazing to have a dead 10M at a low spot of the sunspots
> and have a short opening into the deep South Pacific at sunset where even
> 10W can be loud.
>
> Carl
>
>
>
> ----- Original Message ----- 
> From: D C _Mac_ Macdonald
> To: Fuqua, Bill L ; KM1H Carl H. ; ARC-5 Mail List
> Sent: Sunday, November 24, 2013 10:09 PM
> Subject: RE: [ARC5] FCC General exam
>
>
> I seem to remember having been taught in USAF electronics school (a LONG
> time ago) that 160, 80, and 40 work so well at night because the D-layer 
> is
> activated by sunlight and absorbs those lower frequencies during the day.
> This absorption goes away after sunset, allowing that energy to actually
> REACH the F-layer to be refracted.
> My SWAG would be that of Carl's; right around sunset.

>
> * * * * * * * * * * *
> * 73 - Mac, K2GKK/5 *
> * (Since 30 Nov 53) *
> * k2gkk hotmail com *
> * Oklahoma City, OK *
> * USAF & FAA (Ret.) *
> * * * * * * * * * * *
>
>
>
>
>
> > From: wlfuqu00 at uky.edu
> > To: geoffrey at jeremy.mv.com; arc5 at mailman.qth.net
> > Date: Mon, 25 Nov 2013 02:26:16 +0000
> > Subject: Re: [ARC5] FCC General exam
> >
> > No, the F layer at night is the residual ionized atoms left after no Sun
> > light is
> > shining on it. That is why you get such good DX on 160 80 and 40 meters
> > at night. Because the density of the atmosphere is low at higher 
> > altitudes
> > the
> > atoms and ions are further away reducing the chance of recombination. 
> > The
> > electrons are what actually do the refraction. The interact with each
> > other
> > like balls with springs between them trying to push them apart. They are
> > resonant.
> > This is called the plasma resonant frequency. These act sort of like the
> > parasitic
> > reflector on a bean antenna. Very loose analogy but the simplest I can
> > come up
> > with just now.
> > An atomic physicist and I sat down at lunch one day and talked about the
> > plasma
> > resonance formula and he said it was hard to derive because it is done 
> > in
> > 3 dimensions
> > I suggested trying to derive in in one-dimension and with a couple of
> > napkins and felt
> > point pen we came up with the same formula. This was a calculation of
> > plasma resonance
> > vs electron density.
> >
> > 73
> > Bill wa4lav
> >
> >
> > ________________________________________
> > From: Geoff [geoffrey at jeremy.mv.com]
> > Sent: Sunday, November 24, 2013 8:34 PM
> > To: Fuqua, Bill L; ARC 5
> > Subject: Re: [ARC5] FCC General exam
> >
> > And the E layer is highest just after sunset according to what I just
> > read.
> > Without sunspot activity there is no F layer after dark.
> >
> > Carl
> >
> >
> > ----- Original Message -----
> > From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
> > To: "Geoff" <geoffrey at jeremy.mv.com>; "ARC 5" <arc5 at mailman.qth.net>
> > Sent: Sunday, November 24, 2013 6:25 PM
> > Subject: RE: [ARC5] FCC General exam
> >
> >
> > Well, the F1 and F2 layers are at a lower altitude in the day and merge
> > into
> > the F layer at a much higher altitude at night.
> > So the answer should be B.
> > The propagation depends greatly on frequency.
> > Find some reference to the ionosphere via google or book.
> > 73
> > Bill wa4lav
> >
> > ________________________________________
> > From: Geoff [geoffrey at jeremy.mv.com]
> > Sent: Sunday, November 24, 2013 6:07 PM
> > To: Fuqua, Bill L; ARC 5
> > Subject: Re: [ARC5] FCC General exam
> >
> > ----- Original Message -----
> > From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
> > To: "ARC 5" <arc5 at mailman.qth.net>
> > Sent: Sunday, November 24, 2013 5:10 PM
> > Subject: [ARC5] FCC General exam
> >
> >
> > > Here is a question that I believe they have wrong on the General Exam.
> > > What is the answer with out looking it up.
> > >
> > > G3C02 Where on the Earth do ionospheric layers reach their maximum
> > > height?
> > > A. Where the Sun is overhead
> > > B. Where the Sun is on the opposite side of the Earth
> > > C. Where the Sun is rising
> > > D. Where the Sun has just set
> >
> >
> > I would choose D. Where the Sun has just set
> > If discussing the E layer anyway.
> >
> > Carl




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