TIP: avoiding dried up/blocked ink-jet carts

Transmitter tubes do tend to run hot. Similar to larger mercury rectifier t ubes. In some cases, those had to be shielded (enclosed) due to UV emission s. Back in the day, I ran a 35mm projection set-up that used carbon-arc lig hts. They were driven by mercury rectifier tubes about 10" tall and in meta l enclosures against the UV.

But standard receiving tubes, not so much. And modern microwave oven magnet rons, not at all.

Peter Wieck Melrose Park, PA

As most transmitting tubes are only about 75% or less efficent, they will run hot. A 1000 watt input tube will send out maybe 750 watts best case, usually less, that is 250 watts or more heating the tube not counting the filiment power.

If you do not think a receiving tube is hot, grab a power output tube of an old All American 5 AM receiver, or for that mater, a 6aq5 or similar in other receivers audio output stages with your fingers.