[SADXA] VK6LW 40m DAY Propagaton to Tucson

Wed Dec 26 21:28:17 EST 2018

Hi Jim,

VK6LW is very near the current Dec. 24th Latitude of the Sun, or about -23
deg. Also, I think on Dec. 22nd, the SS was about 10:00 UTC, unless I am
missing something?  So I think VK6LW was about 50 Min. from SS at 0910 UTC??
But it really does not matter, because the point is VK6LW was Q5 copy during
his DAY, and occurred well before his SS. The EMUF Data I have collected
from this very Latitude (Madimbo RF sounding site in S Africa) shows
propagation is possible for VK6LW towards the US from about 3 to 4 Hours
prior to VK6LW Ss.

I also have 40m supporting Data from the DX Maps showing propagation from VK
and ZL stations propagating as much as 3 hours or more prior to SS. 

This is all due to the 40m Propagation Corridor which is a DAY region
between the Terminator and a EMUF = 7 MHz Boundary, about 2500 mi from the
Terminator. This 2500 mi wide 40m DAY Corridor encircles the Earth parallel
to the terminator. 

40m Signals f within this corridor have the condition that f > EMUF. Thus
40m signals pass through the E layer and are propagated by the F layer. 

It is common for 40m signals to propagate in and out of the 40m corridor, or
stay totally within the DAY corridor.  In your case, VK9LW began in the day
corridor and ended up on the night region in Tucson. I have several LP
examples where the propagation began in the DAY corridor, entered into the
night region, and ended up back in a day Corridor region on other side of
world. 

My interest in this subject matter began, as I started to notice significant
DX was occurring during the DAY on the Near Top Bands, namely 80m, 60m and
40m. 40m is the most interesting case since it has the widest Daytime DX
corridor parallel to the terminator. 160m is also very interesting, since it
has the narrowest corridor. 

I will be presenting the theory and concepts behind this subject matter,
with real world supporting examples based on 40m DX MAPS and on 1st hand 40m
experiences at the upcoming SADXA meeting in Tucson on Jan. 17th, 2019.  

I had two Ham Radio 40m Myths when I was a kid:
	1) 40m was great during the day, for working stations nearly 100 mi
away. 
	2) 40m was great during the night, for working adjacent states. 
40m DX never entered my vocabulary with 17W from a 6L6 and with a S40B RX.

73's
Bill W7EXG

-----Original Message-----
From: sadxa-bounces at mailman.qth.net [mailto:sadxa-bounces at mailman.qth.net]
On Behalf Of Jim KF7E
Sent: Tuesday, December 25, 2018 11:18 AM
To: sadxa at mailman.qth.net
Subject: Re: [SADXA] Sllight Chance of Lightning Christmas Day Eve/Night -
per NWS Tucson

     I see it!

     As for prop, I noted hearing VK6LW on 40m 09:10 UTC a couple days 
ago, which is 2 hours before his sunset. Very interesting.

     He was beaming EUR on his LP, and did not hear my 400w and inv-L, 
but he was 539.

     MX to all.

KF7E

On 12/25/2018 5:44 PM, Jerry Wothe wrote:
> Thanks Bill:
> Merry Christmas to you.
> An interesting thing is going on these days on 160 that I have not really
noticed in recent years. Maybe I just missed it. In the morning about and
hour or so before our SR there is one station in Oregon and at least one in
IL who have been working Europe Via SP on 160. In some years past I worked
Franz Joseph land on 160 but never heard lower Europe then. It makes sense
to be able to work that path as it is SS in EU at that time. But I have not
heard a peep of any of the stations being worked by N6TR/7.
> Your posts of LP on 40 in the afternoon has been a LP I worked in the
winter here before. I have worked many SE Asia stations on that path in
years past.
> Bottom line is if one watches the Grayline one will hear some interesting
things.
> Happy New Year to you.
> Jerry
>
>> On December 25, 2018 at 10:31 AM "W7EXG (Bill)" <W7EXG at q.com
mailto:W7EXG at q.com > wrote:
>>
>>
>>
>>      NWS Tucson is forecasting Slight Chance of Lightning from 5pm 12/25
-
>>      through 3am 12/26.
>>
>>      I suspect it unlikely anyone will see this alert notice!! :)
>>
>>      Hope all enjoy the Christmas Holiday Season.
>>
>>      73's
>>      Bill W7EXG
>>
>>
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