7 and 9 pin valve extenders
for testing thermionic circuits in hard to reach places.

repair and testing of some ex military radio gear is sometimes very hard because the circuitry under the valve is heavily obscured. These simple to replicate tools permit probing of valve elektrode voltages.

Dont attempt any RF alignment of  high frequency circuits with the valves on extenders. The extra capacitance may render your adjustment void  and on some RF circuits also permit unwanted oscillation.

Construction is self evident from the pictures.  I had some old ceramic material sockets on hand, so thats what got used. The extender pins are tinned copper wire that is about the same diameter as a standard 7/9 pin valve.  Secure the extender pins with perspex or simpler still, a blob of polyester resin.