Other Workshops: Homebrew Sailboats

In the Dominican Republic I sometimes find myself wanting to take sailing lessons on Juanillo Beach.  Maybe next winter. I've also been following the far more sophisticated wooden boat-building effort of Leo Sampson and the Tally Ho.  All of this helps explain why I watched this video.  And a big part of this is simply an interest in "other kinds of homebrew workshops."  

There is some practical advice for us:  The importance of pilot holes.  The fact that Philip head screws sometimes break (who knew?). 

Check it out.  Thanks to Hack-A-Day for alerting us to this.  And thanks to the Cumberland Rover guy. 

The REALLY BIG Dish: China's Sky Eye

The technology used is really interesting, as is the struggle to maintain a radio quiet zone around the telescope.  The limestone geology with lots of useful sinkholes was very helpful in selecting the site (we have similar geology in the Eastern part of the Dominican Republic).  The contrasts with Arecibo are also quite telling. 

Thanks to Rogier PA1ZZ for sending this. 

The Green Hornet -- My Visual and 10 meter Beacon from the Dominican Republic

This all started a LONG time ago when I built a "Lil Slugger" CW transmitter, designed by Doug DeMaw. The schematic appears below -- it appears in both the W1FB Design Notebook, and his QRP Notebook.  

Last year I decided to put it on the air from the Dominican Republic.  Mike WN2A sent me a programmed PIC chip to key the beacon.  I just connected the output of the keyer to the base of the Lil Sluggers keying transistor.  This transistor just switched the transmitter's driver transistor on and off. 

In the course of messing with this device (and trying to get it to work with a 2 meter beacon) I managed to release smoke from Mike's keyer.  Fortunately, Mike had sent the schematic and I was able to tell that it was probably just the PNP transistor at the very end of the keyer circuit.  I have some 2N3906s on hand.  I replaced the suspect part and Bob was my Uncle.  I consider this a "good repair" -- I had to identify the fault, and then replace the part to make the device work.  

Then came the fun part.  The visual part.  I used the keying transistor from the Lil Slugger to drive a super bright green LED from LighthouseLEDs.  I had in my DR junk box the parabolic mirror from an old car spotlight (the kind you'd plug into the cigarette lighter).  That mirror became the mount for the LED.  Before I got the thing going this year, I had to remove some of the window coating that keeps the UV out of the house.  Unfortunately it was also keeping some of my beacon's photons IN.  It had to go.  I used my wife'd hair dryer to take the coating off.  As you can see, the visual beacon is now really bright.  So far, only one neighbor has noticed the green flashing light.  So far, we have heard from no ships at sea.  But we are hopeful.  Pete N6QW warns of possible cruise missiles.  I am prepared to live dangerously.  

This video shows the set up from inside the shack, during the daytime: 

The ten meter beacon has been doing well and is showing up on the Reverse Beacon Netwok (K1RA and NU4F).  I will improve the antenna and this should strengthen the signal even further. 

Solar Powered Drone from South Africa

 I've been flying a DJI 4K Mini drone here in the Dominican Republic, so I am interested in the whole drone thing.  The technology involved is pretty amazing, with many of the drones featuring GPS tracking systems, onboard compasses, and inertial (gyroscopic) stabilizers.  This in addition to high resolution, stabilized cameras, look-down landing cameras, and obstacle avoidance systems.  Oh yea, if you lose sight of the 249 gram drone, you can just hit the HOME button and it will miraculously fly to its start point and land.  Wow.  

This fellow in Capetown takes things quite a bit further. I like his solar-powered drone.  He has a really cool workshop.  There is something for everyone here:  He uses 3-D printing, carbon fibers, and computer assisted design tools.  And he does a lot of good-old soldering.  I really like his portable wind meter.  I will get one for this very windy location in the Dominican Republic. 

SolderSmoke Podcast 263: DR-PR, UM, DCRX, SKN, Design, PSSST, W7ZOI, FT-101, HW32A, VK, HST, AMP, MAILBAG

Pete Juliano N6QW

February 23, 2026

SolderSmoke Podcast #263 is available for download: 

Audio:  http://soldersmoke.com/soldersmoke263.mp3

Video:  https://www.youtube.com/watch?v=Fn164glxQ6s

Opening 

May 26, 2014, coming up on 12 years! That was the 1^st podcast where Pete N6QW was interviewed by Bill in Podcast #161,  which means 102 podcasts ago. 12 Years of Julian-ismo.  Thanks Pete!  

What to build?  Question faced by VWS Makers Group and by Charlie of RedSummit RF.   Regen?  Test Gear?  Simple oscillator?  

But did you DESIGN it yourself?  What does that even really mean? Barrie Gilbert in Jim Williams' book:  https://soldersmoke.blogspot.com/2025/12/homebrew-you-say-but-did-you-design-it.html

Grayson KJ7UM on a podcast -- Make it your own way.  Copper Clad and Glue!  Manhattan style! "BUILD SOMETHING!:  Tube testers not necessary.  OK to call thermatrons "vacuum tubes."  No ruling on calling them "valves" yet. 

Pete:  

-- When hams were hams -- Turning a Heath monobander into a tribander

-- Simple SSB

-- W7ZOI rigs

-- The Yaesu FT-101

SHAMELESS COMMERCE DIVISION:   Mostly DIY RF!   Patreon!   But no more Amazon.  We do not want to help Bezos make more money. Even if this will cost us.   So please,  consider a donation or a Patreon sponsorship instead.  But no more Amazon through SolderSmoke.  

Bill:   

-- Dominican Republic to Puerto Rico on 2 meters -- status report. 

-- Working Australia on 20 meter SSB in the morning. 

-- The SpiderWeb net. 

-- The Hubble Space Telescope -- an old friend

-- One contact on Straight Key Night (Dean reminded me).  I worked NB1U on 20 meters with QCX from KD4EBM. 

Dean: 

-- The University of Michigan ant the Direct Conversion receiver project.  

-- Boxing up the amplifier.  A tale of woe.  Identifying oscillations.  A QSO with the Dominican Republic: https://soldersmoke.blogspot.com/2026/02/a-qso-with-dean-kk4das-northern.html 

 Travails with other homebrew gear... Trying to find a working transceiver.

AI assisted repair of Bitx40 PA in my Mythbuster 

VWS club station update, tendency of Flex and other SDR makers to not release even basic technical information.

MAILBAG: 

Ian VK3MO  Huge antennas, big signal, friendship with WA3O https://soldersmoke.blogspot.com/2025/11/vk3mo-and-wa3o-brotherhood-of-ham-radio.html

Bob KD4EBM  2 meter propagation info

Todd K7TFC  -- Mostly DIY RF

Mike K6STR  Worked Pete on 40, building for CW and SSB on 2 meters

Grayson KJ7UM    German Avionics,  MMM Origin.  Old Steampunk Homebrew rig: https://soldersmoke.blogspot.com/2025/12/a-very-interesting-old-steam-punk.html   

Phil  W1PJE   Forrest Mims III     Mims's sad denial on climate change. 

Ciprian  YO2DXE         Heard the SAQ Alternator  see: https://soldersmoke.blogspot.com/2025/12/alexanderson-alternator-on-172-khz.html

Tom NS6T:  Very useful azimuth map with grey lines: https://ns6t.net/AzShadowMap/experimental.html

Walter KA4KXX -- 20 meter Direct Conversion Receiver.  FB Walter! 

WN2A Mike   Dos Equis man is BACK! https://soldersmoke.blogspot.com/2026/01/hes-back-dos-equis-man-most-interesting.html

KB4HG Rhett:  On USB on the Old Military Radio Net with a PRC-74.  Want one! 

A QSO with Dean KK4DAS (Northern Virginia to Dominican Republic)

Dean KK4DAS was checking out his new homebrew solid state 100 watt amplifier.  We were talking about it on the phone, then we decided to give it a try on the air.  Above is the Dominican end of the QSO.  It was great to talk to Dean on the air.  Below is how the QSO looked and sounded from Dean's QTH in Northern Virginia:

 

 Next we need to bring Pete into the conversation so that we can have an All-SolderSmoke QSO.  

Attempting 2 meter contact, Dominican Republic to Puerto Rico

It is about 100 miles across the Mona Channel.  That is a longshot on 2 meters, but I got the idea when, this past summer, I regularly heard WIDI 99.5 FM in the Dominican Republic from western Puerto Rico.  So over the fall I gathered 2 meter gear, and got a directional antenna and sent all of this gear to the DR.  

Here is the antenna.  Seven elements. I got it through Amazon.  It came kind of incomplete and without any written or on-line instructions.  AI told me to do exactly the WRONG thing with what they assumed was a reflector.  Fortunately I ran into this YouTube video and learned that it was in fact a "ZL Special" antenna, and that it has, in fact, TWO driven elements.  It was through that video that I learned how to assemble this thing.  

My "station" consists of a Heathkit HM-2109.  It is a VHF wattmeter/SWR meter that I bought by mistake.  But I kept it, and it proved very useful in this 2 meter Mona Channel project.  There is a Baofeng UV-5R (boo! hiss!) and a Yaesu FT-470 that KD4EBM gave me.  I have a Communication Concepts 2 meter amplifier -- I must have picked this up at a hamfest.  It promises 35 watts with 5 watts of drive.  The old CCI amp gives the rig good juju. 

This morning I wrote to the hams of western Puerto Rico: 

--------------------------------------------------------

Saludos desde el otro lado del canal de la Mona! 

Soy radio aficionado:  Hi7/N2CQR.   Vivimos en República Dominicana en Cap Cana seis meses cada año.

He notado que puedo escuchar WIDI 99.5 FM aquí.  Parece que hay Tropospheric ducting. 

Como radioaficionado, me gustaría averiguar si podemos hacer contacto en 2 metros usando la misma propagación. 

Tengo: 

Dos transceptores de FM

Un amplificador a 35 vatios. \

Un antenna directional de 7 elementos con un gain de 11.5 db. 

Estoy a una elevación de 7 Pisos.  Puedo ver el canal de Mona. 

Hay alguien en la costa oeste de PR (tal vez cerca de Mayagüez) quien puede hacer un schedule para probarlo? 

O hay un repetidor en la zona que puede usar para averiguar si puedo -- por lo menos -- "kerchunk"  el repetidor?  

Gracias por su ayuda! 

73  Bill  Hi7/N2CQR

-----------------------------------------

Greetings from the other side of the Mona channel!

I am a radio amateur: Hi7/N2CQR.   We live in the Dominican Republic in Cap Cana six months every year.

I've noticed that I can listen to WIDI 99.5 FM here.  There seems to be Tropospheric ducting.

 As a radio amateur, I would like to find out if we can make contact in 2 meters using the same propagation.

 I have:

Two FM transceivers

An amplifier at 35 watts. \

A 7-element directional antenna with a gain of 11.5 db.

I am at an elevation of 7 Stories.  I can see the Mona's channel.

 Is there someone on the west coast of PR (maybe near Mayagüez) who can make a schedule to try it out?

 Or is there a repeater in the area that you can use to find out if I can -- at least -- "kerchunk" the repeater?

 Thank you for your help!

 73  Bill  Hi7/N2CQR

-------------------------------

Stay tuned! 

Watching the Hubble Space Telescope (an old friend) from the Dominican Republic

 

A recent article about the possibility of an early demise of the Hubble Space Telecope caught my eye.  I first saw HST as it came overhead (a lot) during my first stay in the Dominican Republic (1992-1996).  

Here is an entry from my observation log showing one of my first sightings of HST from the DR: 

2 February 1995: (message placed on COMPUSERVE board) I got a really nice look at the HST this morning (2 February) from my perch here in Santo Domingo. I woke up early and checked the computer for any satellites that might be in the neighborhood. (I'm a ham and have been trying to communicate through the new Russian Hamsat RS-15). I noticed that HST would be visible starting at around 0935 UTC (0535 local); I scrambled up onto my roof with binoculars in hand and began to scan the southern sky. There she was, right on time! I first spotted the satellite when it was in Centaurus (with the Southern Cross glimmering off to the right) and followed it through Scorpio, below Venus and Jupiter until it vanished in the east. Great way to start the day! Yet another benefit of southern latitudes! 73 and Clear Skies, Bill (N2CQR/HI8)

I am back in the DR now; I decided to look for it again.   

The Heavens-Above web site gave good info on the orbit.  So did the N2YO site.  There were a couple of morning passes in January that didn't work out because of local cloud cover,  but last night (January 20, 2026) I managed to see it on an evening pass. It was fainter than I remember, peobably because I saw it at 1930 Local, near  zenith, as it was getting ready to fly into the darkness.  But I saw it.  My old friend, HST.  

Here is the pass that I watched last night: 

There is another good pass tonight.  I will give it another try.  Stay tuned. 

Frank Jones W6AJF on Homebrew, Thermatrons, and VHF

We are in the Dominican Republic now. I thought SolderSmoke blog readers would like the introduction to Frank Jones W6AJF's VHF handbook. (Click on the pictures for a better view. ) The book was published in 1961.  Lots of good homebrew, VHF, and thermatron thinking in those pages. I will be using this book and the implied blessings of W6AJF in my upcoming 2 meter assault on the Mona Passage between the DR and Puerto Rico.  (Thanks too to W3RTV, the original owner of the book!) 

Click on the pictures for a better view. 

Click on the pictures for a better view. 

How VU2RM Got Into the Satellites

 

Readers will remember last week's post about the homebrew rivalry between VU2RM and VU2NR. (Note the bio about VU2RM below).  This morning Farhan sent me this article from a 1970s-era Indian ham radio magazine in which VU2RM describes his early efforts to get onto the satellites. I also tried during the mid 1970s, but I didn't have the kind of magic decoder ring provided (via QSL!)  by OH2RK.  My satellite success had to wait some 20 years, until I was in the Dominican Republic.  More on this below the VU2RM article. 

This morning I replied to Farhan's email:  

Very cool Farhan.  I see that Pete may have an Indian rival for "most SSB transceivers built."  

I got into the satellites during my 1992-1996 stay in the Dominican Republic.   At first, we had no way to get the up-to-date Keplerian elements to predict satellite passes.  Then Compuserve opened up. I had to telephone Miami from the DR to get the Keps.  I ran up a huge phone bill. 

I too built an antenna for these contacts.  Mine was the 2 meter portion of a 144/440 MHz project from 73 magazine called "The Ray-Gun".  I built mine out of scrap lumber and refrigerator tubing.  I still have these elements!  I used them in the beam that I built to listen for YOUR satellite!   In the DR, elevated the thing by 45 degrees and pointed it in the general direction of the satellite.  

RS-11 had a very cool robot aboard.  If you called it just right, it would issue you a serial number.  I have the QSL.

Here are some articles about our satellite adventures.  

https://www.gadgeteer.us/ASTRO.HTM

BTW, Luis Ernesto HI8LEZ visited me during summer 2024 in the DR! 

My hombrew 2 meter beam in the Dominican Republic

Two Spanish Words Useful for Homebrewers: Cacharreo and Artilugio

Luis EA5BRE

Both these words came up during a very nice conversation that I had this morning with Luis EA5BRE on 20 meter SSB.  I told Luis that I had first heard "cacharreo" from Cuban hams who had apparently done a lot of it.  I recently heard "artilugio" being used in a podcast from Spain; they were using it to mean a "gizmo" or a "contraption."  All of us do a lot of "cacharreo" and we build a lot of "artilugios." And we have all done some weeping as a result of our artilugios (see below). 

Google AI says: 

The Spanish word cacharreo refers to the act of tinkering or fiddling with something, often in an attempt to fix, modify, or improve it. It is an informal, colloquial term derived from the verb cacharrear.  This activity is typically done in an amateur way, not by a professional. 

Common uses of cacharreo:

Hobbies and DIY: It is used to describe hands-on hobbies like tinkering with electronics, computers, cars, or audio equipment. For example, a video about "hifi systems" was described as a "Ruta del Cacharreo".

• Minor repairs: It can refer to attempting to fix a broken household item. For instance, "Estuve cacharreando con la TV, pero sin éxito" translates to "I've been fiddling with the TV trying to fix it, but to no avail".
• General fiddling: It can also be used in a more general sense to mean "messing with" or handling something without a clear purpose. For example, "¡Deja de cacharrear con el refrigerador!" means "Stop messing with the fridge!". 

The roots of cacharreo

The word is related to cacharro, which can refer to a variety of items, including: 

• A piece of junk or old, useless object
• A broken-down car
• A cheap gadget
• A cooking pot or dish 

---------------------

Artilugio is a Spanish noun referring to a device, gadget, or contraption. The word is often used informally or with a slightly pejorative or humorous connotation, suggesting that the object is unnecessarily complex, strange, or difficult to use. 

The term can also refer to a trick or ruse used to achieve a goal. 

Common translations include:

• Gadget: A small tool or device with a specific function.
• Contraption: A machine or device that looks strange or complicated.
• Gizmo: An informal word for a gadget or device.
• Gimmick: A trick or special feature used to attract attention.
• Contrivance: A mechanical device, or a clever plan or scheme. 

Etymology
The word artilugio is thought to have an ironic origin, combining the Latin words ars ("skill" or "art") and lugere ("to mourn" or "weep"). The combination humorously implies a device that, despite being "artful," is so complex that it might make one "weep" out of frustration. 

Why I can listen to both sides of VK-G Long Path QSOs in the Dominican Republic

Bottom line:  I think when Australians talk to Brits via long path,  in the Dominican Republic I am between the two. Both have their beam antennas aimed (generally) un my directions.  With an omnidirectional antenna (my 1/4 wave vertical) I can hear them both.  While they are on the Long Path to each other, I am Short Path to both of them. 

Here is my log entry (From the Dominican Republic): 

August 20, 2025 

20S around 0830 UTC  VK5UK Rich and G2YT Peter.  Rich was in LP contact with Peter  My  VFO was moving as the air conditioner kicked in.  I think I was hearing both of them SP.  With VK5UK I was off the side of his beam.  Same with Peter G2YT.  

---------------------------- 

Peter G2YT wrote:  

Yes, Rich and I were working Long Path… I was beaming at the top end of South America (about 240 degrees) and Rich was beaming approx 120 degrees.

------------------------------

Rich, VK5UK wrote: 

Hi, thanks for the email... My beam heading was around 150 degrees from VK long path to Europe you would have been receiving me via the shortest path between us, and I suspect you were being received by Peter on the same path? 73 Rich

------------------------------

Here is a good website that describes (using Australia to Europe) the Long Path and Short Path propagation paths:  

https://www.pa9x.com/long-path-or-short-path-propagation/

Here is a link to Google's new AI (on this subject) 

So Where is My Dominican Antipode?

There you have it.  I like the icons!  

Here is the site: 

https://www.antipodesmap.com/#coordinates-converter

Maybe it is Tropospheric Ducting After All -- 99.5 FM WIDI Puerto Rico Received in the Dominican Republic

 

Invest 94L moved arcoss the Mona Passage yesterday, lowering temperatures, bringing lots of rain and relatively high winds to the area.   I happened to check on reception in the DR of WIDI 99.5 FM (near Mayaguez, Puerto Rico), and was surprised to find that the signal had weakened considerably.  This morning, after the storm passed, signal levels were back to their normal full quieting. This would support the idea that tropospheric ducting is playing a big role in bringing this signal into the Dominican Republic.  I had been surprised by the persistence of the signal -- for weeks it had been full quieting here.  I thought that perhaps I was just receiving it directly, line-of-sight, without the benefit of tropo ducting.  But Invest 94L has made me question this idea. 

I asked Google Gemini AI about the persistence of tropospheric ducting on FM broadcast signals in the tropics.  Here is what it said: 

AI Overview

In the tropics, tropospheric ducting is a frequent, persistent, and often strong phenomenon, especially over and around large bodies of water. Unlike mid-latitudes where ducting is a seasonal event, the meteorological conditions in the tropics are favorable year-round.
Why ducting is persistent in the tropicsHigh temperatures and humidity: Tropical climates are characterized by consistently high temperatures and abundant moisture. These conditions are the primary drivers of atmospheric ducting.

Temperature inversions: Stable high-pressure systems common in the tropics can create temperature inversions, where a layer of warm, moist air sits above cooler air. The sharp change in temperature and humidity with altitude creates the "duct" that traps and bends radio waves over long distances.

Dominance of water paths: Large tropical ocean regions are ideal for ducting. A common ducting phenomenon called the "evaporation duct" is ever-present over the sea surface due to a sharp humidity gradient and is particularly effective for trapping frequencies above 3 GHz. While the FM broadcast band (87.5–108 MHz) is at a lower frequency, coastal areas and islands frequently experience ducting over sea paths.

Atmospheric stability: The general stability of high-pressure systems in the tropics allows ducting conditions to persist for many months at a time. This is observed in areas like the Caribbean and the Persian Gulf, where long-distance radio reception is a common occurrence.

Impact on the FM broadcast band (VHF Band II)Favorable frequencies: The FM broadcast band (VHF Band II) is particularly susceptible to tropospheric ducting. While ducting can occur across a range of frequencies, signals above 90 MHz generally propagate more favorably during ducting events than lower frequencies.

Signal interference: The most noticeable effect of this regular ducting is co-channel interference, where distant stations can override local ones. During an event, a listener may pick up two different stations on the same frequency, or experience temporary loss of reception from a nearby transmitter.

Extended reception: For radio hobbyists, this high frequency of ducting means that signals from FM stations hundreds or even thousands of kilometers away can be received clearly.

Diurnal cycle: Ducting events in the tropics often peak during the evening and overnight hours when surface cooling creates a stable nocturnal boundary layer. Conditions may "burn off" after sunrise, but ducting is common throughout the day during periods of stable weather.

In summary, the specific meteorological and geographical conditions found in tropical regions—consistent heat, humidity, and the presence of large bodies of water—make persistent tropospheric ducting on the FM broadcast band not just possible, but highly probable throughout the year.

A Flight from Chile to Panama: Aeronautical Mobile Contact with KX4WC/AM, with VK3MO in the Group

WA3O sent me an e-mail alerting me to the fact that Mike KX4WC/Aeronautical Mobile would be flying up from Santiago, Chile to Panama City this morning. So I fired up the 20 meter rig and hoped for the best.

Not only was I able to talk to Mike, I was also able to work WA3O, VY2WW, and VK3MO in Melbourne. It was a very FB morning. VK3MO was really booming in. I have worked Ian before -- his 5 over 5 over 5 over 5 array on 20 meters really helps. https://www.qrz.com/db/VK3MO

I was not hearing Mike KX4WC very well until the sun came up over our north-south path. You can see this in the picture below. Thanks to all for this very cool contact.

Ian VK3MO's 20 meter array

Peter VK3TPM had done a very nice profile of Ian and his station: 

https://www.mrarc.org.au/member-profile-ian-vk3mo/

Do I really NEED Tropo to hear the Puerto Rican FM Broadcast Station? Or are we just close enough to do this line-of-site?

 

WIDI 99.5 FM from western Puerto Rico continues to put a full quieting signal into the eastern Dominican Republic.   The station is so regularly strong that this made me wonder if I am really using tropospheric ducting to hear it.  If I was using tropo ducting, I think there should be some variation in signal strength over the course of 24 hours right?  But it is always strong.  Why?  

I checked the distance:  97 miles.   With its antenna at 2800 feet, its visual horizon will be 64.8 miles away.  I am about 98 feet above the ocean.  This means my horizon is 12.22 miles away.  There appears to be a gap, right?  I mean 64.8 + 12.22 = 77.02 miles.   So it looks like there is a gap of about 20 miles.  

But wait!  Mike WN2A reminded me that there is a difference between radio line of sight and visual line of sight.   Radio line of sight = 4/3 of visual line of sight. 

AI explains where the 4/3 factor comes from: 

The radio horizon appears longer than the visual horizon by a factor of about 4/3 due to atmospheric refraction, which bends radio waves slightly downward. To simplify calculations, this effect is modeled by treating radio waves as if they travel in a straight line over a larger, "effective" Earth with a radius 4/3 times the actual radius. This increased effective radius allows radio waves to "see" further over the Earth's curvature, extending the line-of-sight range compared to what is seen by the human eye, which is not affected by atmospheric bending to the same degree. 

So that puts WIDI's radio horizon at 86.4 miles.  My radio horizon is 16.16 miles.   86.4 + 16.16 =  102.56 miles No gap.  We should be able to hear WIDI, even without tropospheric ducting.   

Puerto Rico -- Dominican Republic Tropo on 99.5 FM? Yes, probably

 

Our friend Todd K7TFC in Portland found this in the 1950 ARRL Handbook at an, uh, opportune moment.  TRGHS.  This seems to describe what a I am hearing, especially that "airmass boundary" in the lower left of the diagram above.  

I'm not a VHF guy, and I am a bit surprised at the persistence of this propagation path.  It is 4:30 am here and the adult contemporary rock from Puerto Rico (Kokomo by the Beach Boys!) is full quieting here in the Dominican Republic.  And it is of the same strength during daylight hours. I don't remember this from the winter months, but I may have just missed it. 

Here is what AI (Gemini) says about this: 

https://share.google/aimode/M1HvC7Y893eE5gAcn\

One other factor to consider:   The island of Mona is about halfway across the path.  There are few people there, and there is almost certainly not a repeater of any kind.  But there may be a metal tower or two... 

Gianfranco IU1DZZ and Mike WN2A  both support the tropo hypothesis.  Mike mentions the Hepburn Index.  I will have to read up on that.  Hamilton is also looking at this propagation path.  Thanks guys.  

Puerto Rico FM Broadcast Station Heard in the Dominican Republic -- But How? WIDI 99.5 FM

WIDI 99.5 FM. Booming in during daylight here on the eastern tip of the Dominican Republic. Their antenna is about 2100 feet above average surrounding terrain. That would put the horizon at about 56 miles. But the path is about 100 miles. What do you folks think is the likely propagation mode?

https://en.wikipedia.org/wiki/WIDI

One (of several) SolderSmoke Blog Backups: This one in .pdf form

The SolderSmoke Daily News blog now has more than 4,000 posts, and some 10,000 comments.  This is both good news and bad news.  The good news is that there is on this blog site a vast repository of useful information.  The bad news is that I sometimes fear that all this info might be lost if Google someday decides that its blog service should disappear.  It could happen, and that is kind of scary, so I have been looking for backups, for ways to safeguard this information. 

Several members of the SolderSmoke community have been helping me create WordPress sites that backup the blog. More info will be coming soon.  The Internet Archive and the WayBack machine have also been of great help. 

While here in the Dominican Republic, I have been working on a kind-of compilation of blog articles, with a bit of an intro.  I think readers of the blog and listeners of the podcast might find this entertaining. 

So here it is.  Please download it to your computer.  That will increase the survivability of the blog.  I will probably do a few updates to the .pdf file: 

http://soldersmoke.com/SolderSmoke Blog Book Compilation.pdf