In the early 1980's, Hammond R.F. linear amplifiers for Amateur (Ham) Radio were produced.http://www.hammondmfg.com/claspg.htm
Naturally tube type, built for continuous duty, powered by Hammond "iron" & housed in Hammond enclosures.
Hammond stopped production over 25 years ago. Even now folks are still asking about them (many are still in active use today).
Two versions of two different models were produced:
The HL-2000 (later became the HL-2000A - link to full data page) using two 3-500Z tubes.
The HL-1000 (later became the HL-1000A) using a single 3-500Z tube - designed to be a more economical version of the more powerful HL-2000A.
Offered with this series of R.F. amplifiers in the 1980's, were high power antenna tuners the AT-1500 & 2KW low pass R.F. filters (HF-1000LP)...
In the 1960's, Hammond sporadically offered the HL-500, HL-700 and HL-750 linear amplifiers too. They used quad 811-A output tubes. Not only using Hammond "iron", RF chokes and enclosures BUT also using their then available, air variable condensers (PDF - 239K).
Very little data on these amplifier models has survived...