Good quality banana plugs in 2.5mm??

[rx8pilot]

Anyone have a suggestion for sources of this oddball size in good quality?

I have only found random Alibaba and the samples are marginal at best. The size is not a negotiable spec since I am interfacing with existing gear that has been manufactured since the 80's in that size.

The metal needs to be good quality with a high cycle life. The gold plating should be durable and appropriate thickness. After receiving a dozen options from Alibaba - the sizes are all over the map, the plating is rotten, the resistance is high.

In general, I only buy these in lots of 1,000 so doing a full custom design is not really practical unless my volume was far higher. The best I have found is from a distributor in UK that gets them from an undisclosed Chinese vendor. The quality is passable, but not great and they add considerable cost. The big issue is that they are not reliable. They took months to deliver the last batch I purchased and I am hoping to have some vendor alternates.

[tooki]

Is the 2.5mm the diameter of the plug’s rigid shaft, or of the total diameter of the spring-loaded contacts?

If it’s the latter, what’s the diameter of the rigid shaft? If it’s 2mm, then there’s lots of options from the European banana manufacturers, like Stäubli, SKS, and Schützinger. The latter also has 2.4mm banana plugs.

Indeed, if you look for 2.4mm instead of 2.5mm, you find more results than with 2.5mm, making me think that 2.4mm was once a standard size. (2.4mm happens to be the closest diameter to 10AWG, though this may not be relevant here.)

By any chance, are the sockets in question the 2.6mm ones used for model railroads and the like? If so, the  2.0mm banana plugs fit them surprisingly well. (The 2.6mm model railroad banana plugs are the kind without the sprung basket thing, they’re just a 2.6mm shaft slit to allow compression. So the socket is a simple tube, and the added almost 1mm of diameter on a 2mm banana plug provides for good contact.)

[Neomys Sapiens]

Or, to add to the confusion, do you want to use them in the so-called 'tip jacks'(MIL-C-28901/MIL-DTL-39024) whose NOMINAL diameter is generally given as .080" (2.03mm) with an unsprung plug and a sprung jack?
(Same size as the tips on many common test leads, but some tend to be rather 2.2mm).
Then be careful, because plugs with spring elements and jacks with spring element do not intermate well, often leading to destruction when de-plugging. Here, the unsprung 2mm plugs from SKS (Hirschmann) and their corresponding jacks work quite well.