Power <a href="https://en.wikipedia.org/wiki/triode" class="extiw" title="en:triode">triode</a> <a href="https://en.wikipedia.org/wiki/vacuum_tube" class="extiw" title="en:vacuum tube">vacuum tube</a> used in radio transmitters.  The cylindrical sheet metal structure is a <a href="https://en.wikipedia.org/wiki/heat_sink" class="extiw" title="en:heat sink">heat sink</a> attached to the tube's <a href="https://en.wikipedia.org/wiki/anode" class="extiw" title="en:anode">anode</a> through which air is blown to cool the tube during operation
Hannes Grobe 21:34, 5 May 2012 (UTC)
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>