RADIO BOYS SERIES
By Wayne Whipple, S.F. Aaron, Frank Honeywell, and J.W. Duffield.
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This Donohue series was published in 1922-1923, and consists of at least seven volumes. The only one I've actually read is Whipple's Radio Boys Cronies. From the other books I've skimmed through at bookstores, I believe that books by each author carry on the same characters, but that there aren't any continuing characters between various authors' books in the series. I don't know what the series order might be, and I don't know if there may be others in the series.
Radio Boys Cronies was disappointingly boring. The book is essentially a biography of an idealized Thomas Edison (not surprising, since Whipple mostly wrote biographies) interspersed with the story of Bill Brown, a "valiant cripple boy" (he limps) and his muscular sidekick Gus Grier -- the conceit is that the heroes are listening to a series of shows about Edison on the radio. The lesser characters are all familiar: there is the friendly millionaire who takes an interest in Our Young Heroes, the millionaire's beautiful daughter, the malicious young man who attempts to thwart all of Our Heroes' plans, and the comical fat sidekick who is incapable of sitting, standing, walking, or climbing without falling down. It really was a very boring book, and left me with no burning desire to hunt up any of the others in the series -- although, based solely on the titles, they do sound like they'd be a bit more exciting :-)
Frank Honeywell titles:
1 - RADIO BOYS IN THE SECRET SERVICE, OR, CAST AWAY ON AN ICEBERG -- 1922. Donahue.
2 - RADIO BOYS IN THE THOUSAND ISLANDS, OR, THE CANADIAN YANKEE WIRELESS TRAIL -- 1922. Donohue.
J.W. Duffield titles:
3 - THE RADIO BOYS IN FLYING SERVICE: OR, HELD FOR RANSOM BY MEXICAN BANDITS -- 1922. Donohue.
4 - THE RADIO BOYS UNDER THE SEA: OR, THE HUNT FOR SUNKEN TREASURE -- by J.W. Duffield. 1923. M.A. Donahue (Mrs. Stone's money-order":  p., bound in at end of text.)
Wayne Whipple titles:
5 - RADIO BOYS CRONIES, OR BILL BROWN'S RADIO -- 1922. Donahue.
6 - RADIO BOYS LOYALTY, OR BILL BROWN LISTENS IN -- additional author, S.F. Whipple. 1922. Donohue.
Radio Boy's Cronies