I don't think it's an accurate translation of this sentence. The vannak here definitely means "are there," as in, "do there exist."
Remember, van and vannak are omitted in predicate-nominative type sentences where you're saying "X is Y" or, in questions, "Is X Y?" If you wanted to ask, "Are they [those things there] radios?" you would go with something like, Azok ott rádiók?
No, I don't think that's accurate.
Vannak rádiók? = "Are there radios?" as in, "Do radios exist?" Vannak ott rádiók = "Are there radios there?" as in, "Are there radios not just in general, but at that specific place?"
Simply, "Are there radios?" does not express the location involved in the question.