On 10/7/2016 12:23 AM, Paul Hovnanian P.E. wrote:
Just picked this gadget up at the local junque store. Apears to be an r.f.
tuned cavity. It has a acorn tube inside with marking "5 mA" that I can't
identify. Any info or ideas as to what this might be worth? If nothing, at
least it has a nice barrel micrometer on the end that I can put to use.


Tucker has a manual for it for 20 bucks.
http://www.etestmanuals.com/Search.aspx?Mfg=SRI