[SFDXA] FT4TA

[Ed Callaway]

Don,

It actually looks pretty promising.  I don't have a model for the 2-el vertical dipole arrays they will be using on the higher bands, so I punted and just used a single 5/8th-wavelengh vertical transmitting antenna on their end for what I hope is a conservative alternative.  They say they will be using amplifiers, so I used 500 W Tx power, which VOACAP automatically cuts down to 400 W, due to assumed feedline loss.  (It's about 1 dB.)  I also assumed SSB.  On our end I assumed a 3-el. Yagi at 50 feet.

According to VOACAP, under the above assumptions the bands should be open around these times, short path:

10m:  1200-2100z  
12m:  1400-2200z
15m:  1800-2300z
17m:  2030-2330z
20m:  2230-0100z

10 and 12m should be the most reliable, believe it or not.  (The SSN used was 67, which seems reasonable.)  If you're running barefoot, I would start at 10m and work down.  

Note the interesting property that 10m opens before 12m, which opens before 15m, which opens before 17m, which opens before 20m.  I guess if there's a 6m opening, it'll be at dawn.  :-)  For CW, or better-equipped stations, the "lower" bands actually will open somewhat earlier than I show here -- the signals just won't be strong enough for SSB until later in the day.

I checked long path, just out of curiosity; VOACAP predicts a short (~30 minute) long path opening around 1400z for 12 and 10m.  It's always something to check, but I think I would keep my money on the short path for this one.

For the lower bands (http://sunrisesunset.com is your friend -- run by a guy in Vero Beach)...

On Tromelin, midway through the DXpedition (5 November): 

SR = 0144z
SS = 1427z

On the same day in Ft. Lauderdale:

SR = 1132z
SS = 2237z

...So the period of common darkness is 2237 - 0144z.  SR at Tromelin will be around 8:45 PM EST, so by 9 PM or so it'll be over (well, 20 and 30m might still be open for a bit) and we can all get some sleep before we start again on 10m at 7 AM the next day.  Very convenient, actually, for a Top-Ten Most-Wanted Entity -- no 2 AM wake-up calls for this one.  The biggest difficulty might be working through an EU wall; as far as I can see, when the bands are open to us, they will also be open to EU.

Of course, this is like predicting the weather a month in advance; one really predicts the climate, but what weather we'll actually get, nobody knows.

Best of luck!

Ed N4II.

-----Original Message-----
From: SFDXA [mailto:sfdxa-bounces at mailman.qth.net] On Behalf Of Donald Drennon
Sent: Tuesday, October 07, 2014 6:30 PM
To: SFDXA
Subject: [SFDXA] FT4TA

Can someone who is much better at propagation prediction than I run the times and percentages for on say 40-10 M, FT4TA to here? I think the dates are October 30 - November 10

Many thanks,
Don
N4TZH

Sent from my iPad mini
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