I want to put my 'rubber duck' antenna on a base mount (mag is fine) that has
a bnc connector on it. A web search isn't showing me much.

Do they exist, or is it time to get creative ?

They do exist. I picked up a Larsen mag-mount base with a BNC
connector on it, at a local electronics store's parking lot sale last
year. I don't know what band it was originally intended for
(commercial FM band data-radio application, I suspect), but it handles
2-meter operation just fine with an HT rubber duck.

Getting creative (e.g. with a BNC bulkhead connector and a small metal
case) would also be fine.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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