Found a SO-239 to 3.5mm mono phone plug adapter.
 

I just found and have ordered a couple of UHF Female to 3.5mm plug adapters. I am going to use one of them to hook a Tecsun PL880 portable receiver that uses a mono 3.5mm jack for the external antenna to one of my dipoles. I know the Sangean use this setup and I think the Sony ICF7600 does as well. I am going to make an adapter so I can hook up to my Zenith Trans-Oceanic, and the RCA Victor Strato-Worlds to my outside antennas. They are only available on eBay at CQ Radio Supply. A great outfit he has have saved a great deal of money. I purchased a quality "C" connector, which is an "N" connector with a bayonet mount like a BNC, and a couple of Twinax connectors, for my R390A. The "C" connector was $18.50, the Amphenol "C" connector at Digikey is $126.55. I also purchased a "C" to BNC adapter for $25.95


http://i.ebayimg.com/24/!C!-CQcQ!Wk~...Wl,Uw~~_35.JPG

I have a Sony ICF-SW7600GR (it is an awesome portable BTW), and it uses an 1/8" (I reject your bogus European measurement units and substitute my own) phone jack socket for the antenna.

I know what you mean I have a couple of radios that use a .125" plug hard to find.

Hehehehe... When I got my 1st R-390A, it was back B4 the internet had really taken off, & finding odds & ends was TOUGH... The Antenna connectors for it were pretty much unknown & unavailable, I had the damthing for I guess, 5 years before I got a PROPER connector for it.. until then, I cheated & doubled, tripled, quadrupled over the wire in my longwire antenna til it SORTA fit the female part, & didn't pop out too often...Ignorance is, as they say, Bliss...