D13-27 GH/T Oscilloscope CRT;
<p>This is a 13 cm flat faced, relative  short oscilloscope tube (35 cm max), with post deflection acceleration by means of a helical electrode.
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Manufactured by Tungsram, Hungary, 1970s.
<a href="//commons.wikimedia.org/wiki/User:Mister_rf" title="User:Mister rf">Mister rf</a>
<span class="int-own-work" lang="en">Own work</span>