6474km TEP contact on 144 MHz from Argentina to a ship off the coast of Florida - 9th Dec 2024

Over the last few years, I've reported on many Trans-Equatorial Propagation (TEP) contacts from South America to the Caribbean on the 144 MHz band... links on my 144 MHz page.

For this mode of propagation at 144 MHz, signals must generally cross the Geomagnetic Equator at right angles. This usually means that stations in the south of Brazil work places like Guadeloupe, St Martin & Puerto Rico. Stations near Buenos Aires in Argentina work stations in Curacao & the Dominican Republic.

There has been a distinct lack of 144 MHz TEP openings further west in South America mainly due to a lack of stations at one or both ends of the paths.

So it was a really big surprise to hear that Carlos, LU7MC in the west of Argentina managed to complete a contact with Yuri, UT1FG/MM on a ship to the north of Cuba!

The contact was made using the Q65B mode on the 9th of December 2024 at 01:34 UTC. This is just after 20:00 local time for both stations which is about the peak time for evening type TEP.

The distance was in the region of 6474 kms which is exceptionally long for a 144 MHz TEP contact for South America.

The map above shows just how close UT1FG/MM  was to the Florida. His ship was just 80kms south of the road going to Key West and about 170kms south of Miami.

It's hard to know for certain but I suspect that the TEP signal from LU7MC almost certainly reached Florida. It was most likely that there was nobody active there and looking.

Mode of Propagation... As indicated already, the mode of propagation was TEP - Trans-Equatorial Propagation. There may have been an extension at the northern end of the circuit with some marine tropo / ducting north of Cuba.

Mode of contact... The Q65B mode was used for this 144 MHz contact. The screen shot from LU7MC is shown below...

As you can see below, the signal level was about 0dB to -8dB which is probably too weak for SSB but should be strong enough to be heard by ear and a CW contact would be possible.

The screen shot from UT1FG/MM is shown below...

The signal levels were about the same at -4dB to -8dB.

Equipment... Carlos, LU7MC is located in the city of Mendoza in grid locator square FF57OB. He was running 100-watts into an array of 4 x 10-element Yagi antennas.

Yuri, UT1FG works on a commercial ship and was Maritime Mobile between Cuba and Florida in grid locator EL94PC. He was running 200-watts into a single 7-element Yagi antenna.

In conclusion... This really was an important contact on the 144 MHz band because it shows that there is a very good possibility of a TEP path from the west of Argentina to Florida. Could it extend even further north to some of the other southern US states by tropo? Could the stations in Chile get in on the action?

The really big question is if anyone in the United States is paying attention and is going to try and make a contact?

Link...
a) For more information on long distance 2m contacts, see my 144 MHz page.

5,800 km TEP opening on 144 MHz between the Dominican Republic and the west of Argentina - 29th Jan 2023

Very long distance contacts in the region of 5000-6000 kms on 144 MHz from the Caribbean to the south of Brazil, Uruguay and the area near Buenos Aires in Argentina are reasonably common via TEP (Trans-Equatorial Propagation). 

The geometry is just right for these contacts ...a) Population centres at each end of the path with active amateur radio stations ...and b) At right angles to the Geomagnetic Equator.

This map from the 2nd of February 2022 shows a typical opening...

All the paths tend to be parallel to each other as they cross the Geomagnetic Equator at 90 degrees. However even in the example above, you can see a few paths that are not exactly parallel.

LU7MC... Carlos, LU7MC is in the west of Argentina and active on 144 MHz for many years. His location is shown on the map at the top of the post in the far west of Argentina. For Carlos, the other end of his usual TEP path falls in areas further west in the Caribbean around Jamaica and Cuba, areas where there is very little 144 MHz activity.

Carlos writes..."I always wondered the same thing, why no TEP? Many years ago my interest in VHF DX awoke and I began to investigate. I believe that one of the main obstacles is the small number of operators who, are unaware of TEP and miss out on the opportunity to experiment with the different types of propagation at 144 MHz and higher.

After a long time of trying (13 years) it finally happened!! A TEP contact from the west of South America on 144 MHz :  LU7MC - HI3I Q65B 5827Km, Very atypical conditions where the strict Trans Equatorial propagation theory seems not to apply. It was always thought that it would occur with stations further west in the Caribbean."

As Carlos writes, it does seem to have been an unusual TEP opening where the path was not quite a right angles to the Geomagnetic Equator. 

It also shows that location is everything for TEP... someone near Buenos Aires can almost make daily 144 MHz contacts on TEP with the Caribbean at certain times of year and someone in the west of Argentina has to wait 13 years!

Carlos sent on a few images. This one shows the predicted map of the critical frequency of the ionosphere around the time of the TEP opening. Notice the less intense zone over the Geomagnetic Equator in South America and the more intense region either side which sets up the perfect conditions for a TEP opening.

This screenshot from Carlos shows that the contact was made on 144.180 MHz using the Q65B weak signal mode. Signals are in the region of -12 to -14dB which is just about detectable to the human ear. A CW contact would be very difficult at this signal level.

Note that the time is in UTC. Evening time TEP usually peaks around 8pm local time.

This final image shows the solar conditions on the left with the Solar Flux at 138 and the K index at 1.7. The right hand side of the image shows the confirmation of the contact via LOTW (Logbook of the World).

Chile (CE) ??? ...Now that there has been a successful TEP contact on 144 MHz from the west of Argentina, what about Chile? Is TEP possible from Santiago? Are there any stations in the west of the Caribbean interested in 144 MHz?

220 MHz and 432 MHz??? ...I would be interested to hear of any TEP openings at 220 MHz or 432 MHz. Will the distortion make digital weak signals modes unusable at the higher frequencies?

Thanks for Carlos, LU7MC for the above information and congratulations on your FB TEP QSO.

Link...
1) For more TEP contacts, check out my 144 MHz page HERE