This page shows the Russian SK1A tube socket. Below at left is the SK1A socket; at right is the socket with a GU74B (4CX800) installed.

This is a 7-pin socket made of high quality dielectric. An Annular 0.01 uF screen grid bypass capacitor is built into the socket which may be reconfigured to remove the effect of the capacitor or provide grounded grid operartion when required. All tube pinout electrode connections and all wiring points for solder are silver-plated.

Below at left is a top view of the socket; at right, bottom view.