smoke
n.— «I think Tree means to tune the gamma match with the variable capacitor for best transmitter output, or “maximum smoke,” as it is sometimes called.» —“The K7RA Solar Update” by Tad Cook ARRL Dec. 1, 2008. (source: Double-Tongued Dictionary)
Further reading
The words tough, through, and dough all end in O-U-G-H. So why don’t they rhyme? A lively new book addresses the many quirks of English by explaining the history of words and phrases. And: have you ever been in a situation where a group makes...
Aubrey in Waco, Texas, says her mother used to warn the kids against contracting honkus of the bonkus, a fanciful name for a contagious disease. This colloquial term probably comes from the words bonk and konk, meaning “to hit” or...
Every good transmitter operator knows that you’re supposed to “dip the smoke and peak the flame”! A dip in the current when tuning the final amplifier stage indicates that the circuit is in resonance, and thus at maximum efficiency. Then the output coupling is increased just to the point of maximum power output; if it’s set too high, it’ll detune the circuit and cause loss of power, or worse yet, unwanted signals such as harmonics or parasitics, which sap the signal strength even further.
Also may relate to the old hot-rod auto maxim: “Set for skim and tuned for minimum smoke!”