Wow, cool to see hfunderground has added a part 15 specific section. Anyway , there's some cool knight broadcaster stories at knightkit.com/fanstories.html They were apparently very capable. The range seemed to average from a few blocks to a mile, but some of the more non compliant installs faired much better, as one of the stories explains:
Excerpt:
".....Our antenna ran about.. 900 hundred feet, a simple long wire, strung about 30 feet over the ground. Our tests showed us getting pretty good coverage out to about 10 miles. As kids, we didn't know any better and thought them rules about antenna length didn't pertain to us.
Our shows were the latest "Nifty Fifty records," news from last nights newspaper and assorted comedy skits...."
There's another story the antenna was fabricated using a fishing pole to support the wire on top the house which got out a solid four miles in all directions.
Elsewhere there is a webpage about someone who still uses one of the original knight kits for broadcasting today, but he only does it one day a year.. every year.. I forget the details and now I can't find the link, but it was a license AM station who does it.. Does this story sound familiar to anyone? It's probably the same story which Kingbear refers to.
Also recall someone at the antiqueradio.com forums mentioning they had utilized a knight kit for their drive-in theatre in the 1960s
Another cool story involved an FCC visit at
https://nofars.net/jacksonville_radio_collection/fcc_visits_fun_radioExcerpt:
"..... The polite FCC official made it clear that we could not use another licensed call sign, WFUN, that our antenna length was excessive giving too much coverage area. There was about 20 feet of coax from his two story home going to a 3 foot metal antenna up about 35 feet above ground..."
Lastly, of worthy mention, in the late 1950s at least one of the National parks had been using the knight kit broadcaster in a lead car for the tourist caravans following behind.
There are now Knight Broadcaster replicas for about $200 on ebay, but he doesn't supply the tubes with the sale... What the heck!