[SADXA] 40m Daytime DXPropagation Corridor- Questions - Bill Davis W7EXG-

W7EXG (Bill) W7EXG at q.com
Wed Jan 23 21:15:09 EST 2019 

Hi Larry,

Please see my last post to Dave (W7AQK) on 30m propagation relative to my
40m propagation discussion. 

I pointed out in my presentation that on 40m prior to SS (within about 1-2
hours of SS) 40m DAY propagation from the West US to DAY BY, HS, YB Land
etc.. is most likely Long Path. Seasoned 40m DXers concur. In addition, I
rotated my 3 ele 40m beam LP/SP to verify. 

Your 30m propagation discussion sounds very familiar, except it is on 30m.
I am guessing that 30m and 40m paths may also be similar. You may have
perhaps been working the HS1NGR on LP at 140 deg on your inverted V.  So for
those who have 30m beams, pointing them towards this region of the world may
prove fruitful at an hour or so before SS. 

Jerry, W6XI has suggested that the FT8 mode is taking otherwise CW or SSB
contacts off these modes. He may be right! 

The other day, I checked 15m SSB frequencies and CW frequencies and it was a
dead band. But However, I could hear the FT8 signals? If FT8 did not exist,
would I of head a CW or SSB signal? So I decided to call SSB CQ on the dead
15m band. ZD7FT came back to me!! I think it floored us both!! 

So, I think if you hear the FT8s on a DEAD BAND.. go for it!! FT8 is now
becoming the "beacon" stations alerting us all to an open band -- to
somewhere!!

Thanks for your comments Larry.

73's
Bill-W7EXG

-----Original Message-----
From: Telegrapher [mailto:lawrenceg94 at gmail.com]
Sent: Tuesday, January 22, 2019 10:12 AM
To: W7EXG (Bill)
Subject: Re: [SADXA] 40m Daytime DXPropagation Corridor- Questions - Bill
Davis W7EXG-

I am curious about 30M as well and agree that it is an underutilized band
where DX is concerned.  Yesterday, the 21st. i worked HS1NGR at 5:30 in the
afternoon when i should have been hearing Europe and/or Africans like 9LY1JM
who is of course off the air now.  I run  25W to an inverted V at 15 ft on
30M so no powerhouse or antenna giant at this location.  Besides that i have
the Dragoon mountains about 6-7 miles to the west. The other stations i
worked closely in time were both on the east coast.  No other Pacific area
stations were heard.

larry

W0OGH

On 1/18/2019 11:56 AM, W7EXG (Bill) wrote:
> SADXA Members
>
> Thanks to all who attended the 1-17-19 SADXA presentation on the 40m 
> DX Daytime Corridor. Please feel free to ask questions via the 
> reflector or to me off-line (W7EXG at Q.COM) regarding the presentation.
>
> Here, I will try and address some of the questions or comments made 
> during the presentation.
>
> I believe a question was asked regarding Tucson to S. Atlantic paths 
> at Solar Noon by Jerry W6XI.  Jerry was correct; there is no 40m 
> Daytime DX propagation to the S. Atlantic region. I determined that 
> after about 2100z on Dec. 21st, the path is likely to open up.  This 
> is because at Solar Noon, these S. Atlantic paths must cross the 
> "restricted" boundary (EMUF>7MHz and High D absorption) preventing 
> such propagation. I generated a graphic on this particular path case and
emailed to Jerry.
>
> Jerry also asked about the Solar Noon DX Award Winning Path from W3LPL 
> MD to YC land. Why not more paths?  In thinking about this, W3LPL is a 
> CW skimmer station (or visa versa), and most likely just heard the YC 
> station. I don't know how the DX MAP web site works, but other YC or 
> YBs may have been heard but not reported in the timeframe window 
> specified. I also know from my own experience, that I have heard many 
> LP 40m DX stations that I never saw on the DC Maps to AZ? My only hope 
> is the paths I did report on were valid, as they supported the 40m DX 
> Day propagation corridor concept.  I did all I could to insure both 
> calls were highlighted and valid at the ends of the DX MAPS paths.
>
> The seasoned 40m DXers also confirmed that most of the post SR to pre 
> SS day-day 40m propagation was in fact LP, and not SP. I presented 
> that I had also personally confirmed LP for the DAY propagation to 
> Asia / Indonesia day areas 1.5 hours prior to AZ SS. I made the point 
> that the Solar Noon D-absorption between these two regions had 
> constant lateral path D-absorption, preventing the SP.
>
> It is true that the hop loss listed in presentation was for 
> D-absorption loss ONLY. This was in response to Wes's N7WS Question.  
> The ground Loss is about 5.5 db/hop for 7 MHz @ 23 deg elevation angle 
> and thus comparable to the D-absorption loss - a correct observation 
> by Wes. The sea surface loss is only about 0.16 dB/Hop for same 40m 
> condition. So, for 3 F2 hops over ground to the terminator, a 16.5 db 
> loss must be added. For 3 hops over sea to the terminator, only about 
> a 0.5dB loss is added. The ramifications of
> this: - East cost to EU, or West Coast to Asia area and more has very 
> small sea loss to the respective terminators. However, the 
> D-absorption loss will dominate the loss over sea to the terminators as
discussed.
>
> There may have been other technical questions I cannot recall to 
> address here, so please do not hesitate to ask again if questions were 
> not addressed to your satisfaction.
>
> If the SSN remains 0, (Low SFI), it is possible again to have another 
> opportunity next Dec. Solstice timeframe for some exciting 40m DX 
> propagation during the day, as discussed. But don't blink; it does not 
> last too long.
>
> 73's
> Bill W7EXG
>
> -----Original Message-----
> From: sadxa-bounces at mailman.qth.net 
> [mailto:sadxa-bounces at mailman.qth.net]
> On Behalf Of W7EXG (Bill)
> Sent: Thursday, January 10, 2019 8:48 PM
> To: 'Southern AZ DX Association E-Mail Reflector'
> Subject: [SADXA] SADXA 1-17-19 Presentation - ABSTRACT-- 40m Daytime 
> DXPropagation Corridor- Bill Davis W7EXG-
>
>
> SADXA MEETING PRESENTATION
>
> DATE: 1/17/2019
>
> TITLE: 40m Daytime DX Propagation Corridor
>
> AUTHOR/PRESENTER: Bill Davis - W7EXG
> SADXA Member, Motorola Retiree - EE
> Licensed: 1956 (62 years)
>
> ABSTRACT
>
> A 40m Daytime DX Propagation Corridor will be defined as a 40m DX day 
> region adjacent to the terminator, having a width W defined between 
> the terminator and an EMUF=7MHz boundary.
>
> This results, since the E layer electron density decreases between the
> EMUF=7 MHz boundary and the terminator. This allows the 7 MHz signals 
> to penetrate the E layer and propagate via the F2 layer in this day DX 
> corridor region.
>
> The basics of the E layer are presented, including the critical E 
> frequency [foE](E layer Plasma Frequency), and the M factor associated 
> with the Angular Penetration of the E Layer. EMUF will be defined, and 
> EMUF equation developed for typical 40m 23 deg elevation.
>
> The world wide foE data is presented as a function of Solar Zenith and 
> latitude. Specific EMUF data vs Time is presented from the Austin (30 
> deg
> Lat) and a South American (-22.7 deg) RF Ionogram sounding Sites, 
> taken during the December Solstice.
>
> The seasonal variation of the terminator [and 40m Day DX Corridor] is 
> also shown, including the December Solstice when the Solar Noon 
> northern terminator boundary is only ~1100 mi from the northern US 
> border.  This is the ONLY seasonal time, when almost the entire US is 
> in the 40m DX Corridor during the day, including Solar Noon. This 40m 
> Day DX condition is best, when ionization of the E and D layers is 
> minimal, such as during LOW SOLAR radiation (like NOW!).
>
> D-absorption is also graphically shown as a function of the Solar 
> Zenith and Sun Spot Numbers (SSN), including the D absorption expected 
> within the 40m Day DX Corridor.
>
> Finally, 40m DAY DX propagation corridor examples are presented from 
> Screen Captures of the actual 40m DX paths from DXMAPS site. The 
> included 40m examples are: Day-Day, Day-Night, Day Western States, Day 
> Eastern States, Observable D absorption effects, Near SS Long Path 
> propagation, impossible paths with bogus call signs, and Solar Noon 40m DX
propagation.
>
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