[ARC5] FCC General exam

Tue Nov 26 13:51:02 EST 2013

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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