In article ,
"Geoffrey S. Mendelson" wrote:

On another list, populated by people with good guessing skills, poor memories
and so on, the question of where did the RG numbers come from?

The most popular answer told with the most auhtority is that RG stands
for "Radio Guide", as a device, the predecessor to wave guides.

I was under the impression, and may have read from a better source that it
does indeed stand for Radio Guide, but that was a tile of a book.

Is that the case, are we all wrong?

Geoff-

One problem I've found when researching old information on the internet,
is that history appears to have started with the internet's invention.
There is a lot of old printed data that may never be typed into
machine-readable form unless someone needs it.

This is the first time I've heard this explanation of RG. It was my
understanding that RG was a relatively arbitrary military designation.
You will find other designations related to Co-ax connectors such as UG.
I'd look for older military documents that listed various other
designations, such as ARC-5, BC-459, et cetera, where each letter has a
meaning related to the equipment's use.

I doubt that "guide" was used prior to microwaves. Co-ax has two
conductors. A waveguide has a single "conductor": its inside wall. In
other words, it appears to guide the energy rather than conduct it.

Fred
K4DII