A hundred years ago this month, this savvy advertiser realized that scouts would be a huge market for the magic of radio. Wireless merit badge had been introduced in 1918, and radio was a young man’s game. This ad from the Wireless Equipment Co., Inc., of Newark, NJ touted the company’s ABC Unit detector.

The unit was a complete crystal set, but the name referred to the fact that it could be added to other units in a modular fashion. After starting with the crystal detector, a two-step amplifier could be added, or a vacuum tube detector could replace the crystal.

The booklet describing the set was only a dime, but the price of the set would have been out of reach of the impecunious scout. It sold for $24.50 which, according to this inflation calculator, works out to $375 in 2021 dollars.  The ad appeared in the November 1921 issue of Boys’ Life.