Old Transmitters? Ya gotta understand the mind of Ham radio enthusiasts! They were probably looking for older tube-type gear to obtain and operate!
Some older (and not so old!) operators used AM (one of the old modes of operation (still used today), search out old AM broadcast band transmitters that are being discarded to retune and use in 160 meters (1.8 to 2.0 MHz), the Ham band just above the AM broadcast band. They also retune them for 75 and 80 meters, the band above that at 3.5 to 4.0 MHz.
At reduced power levels (we are allowed 1500 watts PEP), the old tubes will last a lifetime. With the audio processing and good mics, these stations sound GREAT! Please note that Ham radio operators are NOT broadcasters, we are communicators...we just like great gear to use- we are allowed to convert practically anything for Ham radio usage.
Some of these stations exhibit rich, warm audio, even though these operators are only talking. If you have a shortwave receiver, tune around 1.965 MHz, +/- a little, 3.880 to 3.895 MHz, AM mode and give a listen, especially on winter nights, when the atmosphere is clearer from lightening static (and the transmitters keep our "shacks" warm!)
A good website to check out as well, to look at some old AM broadcast band transmitters in use for Ham radio rigs is: http://www.amfone.net/Amforum/index.php
Enjoy! Bud, KC4HGH, Mobile, AL
Incidently, KWHN an AM station here in Fort Smith AR used to broadcast on 1320 and 1620 with the idea 1320 would be turned off. Flooding and technical problems has caused them to abandon the 1620 frequency.