Unusual tube sockets

[Richardgr]

I recently bought a job lot of old valves, and amongst some tube sockets were some unusual ones. Interested if anyone has any experience using them!

The ones in the first photo are ceramic. How would they be fitted? Were they designed for a particular purpose? I am going to try then under a top plate, but having done the same with UX4 ceramic sockets, the hole size has to accomodate all possible base sizes, and also it is hard to fix the socket permanently.

The second photo, the black ones, will fit a Loctal tube, but I wonder at the logic behind the side force on the pins, so they must be for another type of tube?

[JonSnell]

You are correct in your assumption;
The ceramic sockets fit beneath the chassis.
The black ones are just how they are. Side contacts or tubed contacts, it is a manufacturing option and probably side contacting is cheaper to produce and easier to assemble.
Difficult to see properly as we only have 2d.

[G6Tanuki]

When fixing the ceramic sockets, make sure you remove any 'burrs' or other surface imperfections from around the big central hole and the smaller holes for the fixing screws, as the ceramic can crack if there is something that stops it seating perfectly-flat on the panel.

Also consider using fibre washers between the metal washers under the fixing screws to provide a degree of 'compliance' in the mounting. Don't overtighten the fixing nuts - if you are worried about them coming loose [they should be not much more than finger-tight] put a blob of nail-varnish on the threads - this will lock them in place but not so firmly that they cannot be removed in future.

[turretslug]

Those Loktal sockets look to be wasteful of Bakelite and intended to have lots of inter-contact capacitance whilst giving poor contact reliability.... I might be being harsh there, but maybe that's why they're unusual.