I happened to find these University Sound amps while looking for an LWT (Line Wattage Tester). I didn't realize until now that university Sound was a division of LTV Ling Altec.
Just mentioning them because they are USA-made and reasonable priced. These would be good for cathode/grid modulation of tube RF amps. My friend used cathode modulation on a 250TH with a similar sized Altec amp.
https://www.ebay.com/sch/i.html?_nkw=university+sound+amplifierThe 70's vintage USA made ones have the stylish 70s cabinets with the 'chevron' sides and usually blue. They are mostly 35 to 100 Watt sizes and have 70V and 25V outputs in addition to a speaker (usually the 4 and 8 Ohm) output.
There are later units made in the USA also. If so it will say on the back.
If it doesn't say made in USA, then it's not.
