Super Atlantic tropo!

I’d been keeping an eye on the F5LEN and Hepburn Atlantic tropo forecasts prior to the 20th of May because they looked promising for good propagation towards the south:

Hepburn North Atlantic forecast 06z May 20, 2015

Hepburn North Atlantic forecast 06z May 20, 2015

F5LEN Atlantic forecast 00z 21st May, 2015

F5LEN Atlantic forecast 00z 21st May, 2015

Lots of bright colours over much of the North Atlantic! There looked to be some possibility of a repeat of Dave, PJ4VHF’s incredible reception of the Cape Verde beacon, over a distance of some 4700km (and perhaps further?), as well as a north-south path touching on Ireland.

Up until lunchtime on the 20th there was nothing other than a slight enhancement on my AIS receiver (a useful propagation tool at 162MHz, online at MarineTraffic) showing ships slightly further south of Cork than usual – certainly nothing exceptional. I wasn’t even hearing the stalwart ED1ZAG beacon in IN53 but the forecast maps were marginal for that direction.

At approximately 14:35z, a weak cw-keyed signal appeared just very slightly above 144.436MHz, rapidly becoming strong enough to identify as D4C in HK76mvThe Monteverde Contest Team’s beacon is at a distance of some 4165km from EI3KD, with a tolerance of five kilometers or so, which probably makes it the furthest tropo distance yet heard from within IARU Region 1.

I immediately spotted the beacon and commented in the ON4KST chat to alert others, and shortly afterwards Tom, EI4DQ in IO51wu also logged D4C. In fact, at that time it seemed he was copying the beacon slightly better from his location a few kilometers to the south and closer to the coast, showing just how marginal these paths can be!

The beacon displayed very slow and deep fading over a period of tens of minutes but did get very strong at times, such as this recording I made at 18:38z on the 20th:

Interestingly, at the start of the opening there were no other indicators on 144MHz, i.e. absolutely nothing from Madeira, the Canary Islands, or the Spanish mainland. ED8ZAA did finally appear at around 18:30z climbing to a pretty decent strength, and contacts followed with EA8AVI (IL28fc, 2716km) and EA8TX (IL18qi, 2711km).

In the meantime, Xara D44TD had gone to his home location in HK86no to attempt a contact but, unfortunately, there was no tropo link to him despite many hours of trying. Xara is located on a different island in the Cape Verde group, more than 200km east of D4C and, being near sea level, is some 750m lower: Either, or both, of these factors would easily explain the different propagation. Also, I never once heard the CS3BTM beacon during this opening, which is almost exactly on the path to D44TD – at the time I thought that beacon was QRT but I’ve since seen it spotted on the dx cluster, so it just goes to show how selective the path was. Anyway, huge thanks to Xara for trying so hard.

The D4C beacon finally faded at approximately 04:30z on the 21st May, so it had been received here, non-stop, for just about 14 hours. This, for me, was a truly memorable experience which is only likely to be topped by a two-way contact with D4… one day!

5 thoughts on “Super Atlantic tropo!

  1. Pingback: VHF: maps of the 2m beacon reception | D4C Monteverde Contest Team

  2. Pingback: Super Atlantic tropo EI3KD listened D4C/B on 144.436 MHz | HB9DUR

  3. Dave Pedersen


    Greetings from Bonaire. I would like to email offline with you about Transatlantic experiments this spring. Please drop me an email.


    Dave PJ4VHF

  4. Wayne Overbeck, N6NB

    Mark, greetings from California. I was very interested in your posting about hearing the D4C beacon on two meters for 14 hours. I’m thinking seriously about taking the 10-band suitcase station that I’ve been using to work California from Hawaii on an expedition to points east, either somewhere in the Caribbean or Cape Verde. Flying to Cape Verde from here is a long flight, but it’s certainly possible. I have ordered DB6NT transverters for the Region I microwave bands (2320 and 3400 MHz) so I can attempt to work stations in Europe if I go to Cape Verde. My W6-KH6 contacts were on 2304 and 3456 MHz. There’s more information about working the Pacific duct on my website, If I make a trip to either Cape Verde or the Caribbean, should it be in May and June? In the Caribbean, I’m thinking of Puerto Rico because it has mountains as much as 4,300 feet above sea level. The U.S. Navy’s research on elevated ducts (Project Tradewinds in the late 1950s and 1960s) suggested that the duct are high on the western end, so a station on a mountain in the Caribbean might be in a good place for this. It’s certainly true that stations at 4,000 to 8,000 feet elevation in Hawaii have far better signals on the mainland than those near sea level. I notice that you heard the D4C beacon at 2,300 feet when you could not hear a station near sea level in the Cape Verde Islands. I’d love to hear from you by email. 73 de N6NB

    1. Mark Turner Post author

      Hi Wayne, that would be some undertaking but I wish you the best of luck if you give it a go! I’m sure there would be plenty of support, in terms of stations qrv, from Europe. It’s difficult to suggest the best time of year; Hearing D4 from Ireland is really quite rare (less rare from the south-western UK) and I’ve heard it only three or four times in five years, in all seasons. Certainly either May or June is a good choice, as the Azores High is shifting a little further north and sending more ridges this way. Delaying until June would also increase the possibility of Sporadic Es on the lower VHF bands, i.e. 6m, 4m and 2m and some combined propagation mode qsos? The Caribbean-Europe path is a complete unknown, but tropo paths may become more likely as climate change starts to increase the western extent of the Azores High. There are an awful lot of slim-chance happenings that have to line up, but that doesn’t make it impossible! Please keep us updated with your plans, 73, Mark


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