Robert11 wrote:

For a receive only application, using coax from the Balun of a simple
outside antenna to the receiver, is a loss of, e.g., 2.5 db
"meaningful" ?
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The answer depends on the noise figure of your receiver. Most modern
receivers have very low internal noise and will work fine under the
conditions you describe. Older receivers, especially tube sets,
generate so much internal noise that it may be stronger than the signal
you are trying to receive and the 2.5 dB loss will render the signal
inaudible.

In other words, it depends. :-)

Bill, W6WRT