I asked this one:
How can I know over what distance or at what speed I can communicate?
and it was closed as "too broad". However: this was not closed:
What bands and modes will give me voice at 3,000 miles?
The only difference, I'd argue, is that the latter question specifies some details that are insufficient to answer the question. The answers are the same: you can't know.
When people ask "Is [PROPAGATION SCENARIO] possible?" without specifying relevant parameters such as:
- path loss
- transmitter power
- antenna gain
Then the answers all follow this form:
Your question is unanswerable. Now, let me just say some unfocused things about radio.
These answers are almost arbitrary. Look at some of the statements made in response to that question:
For straight distance it's hard to beat digital or CW
You probably want to be able to use digital modes.
you need a satellite phone
20m is the best band
You could set up an Elecraft K-line station (500 Watts), plus a tower and a beam for maybe $10K
you'll want a huge yagi antenna on a large tower
I would say 20M is the best band to aim for.
you need high power, high gain antennas for several bands, and several years of intensive practice
your best bet is probably 40 m.
These statements are a combination of:
- general advice where the question might as well have been "How do I make contacts easier?"
- you'll want a huge yagi antenna on a large tower
- folklore, opinion, or partial truth without good explanation or references, often contradictory:
- 20m is the best band
- your best bet is probably 40 m.
- 80m and 40m have even more potential for long distance.
They are, in my opinion, pretty useless. Notably, none of the questions have actually discussed HF propagation in any depth. A couple have flirted with the concept of critical frequency, but that's it. None have mentioned any real HF modeling tools, or cited any references. There's not even a single link in all the answers. The closest we get to sources are "G5RV" and the names of a few digital modes.
Therefore, I propose a new off-topic close reason:
Questions on what propagation scenarios are possible must include or ask specifically about relevant parameters such as path loss, detection sensitivity, and transmit power. Without this information, objective answers are not possible. For more information, please see the help center.
The help center can then explain why these questions are impossible to answer, and give pointers to the information that would help one ask a useful question (Friis transmission equation, Shannon's law, ...)
Shortly after I wrote this, "voice at 3,000 miles" got another answer, despite already having an accepted answer, and being over three weeks old. It doesn't really add any new information but one more arbitrary suggestion: "find a local club. Find some used gear."
I think this further underscores why this sort of thing needs to be closed. This isn't the high-quality Q&A unique to the StackExchange format: it's an undirected discussion on HF operation. The question to any of these answers is more like "How do I get started on HF?" I'd hope that everyone will agree such a question is too broad, and I think any question that asks the same thing in different words should likewise be closed.