In the late 50’s International Crystal sold a VFA-1 tube cascode 6 meter amplifier. I use it on a vertical 6m antenna to monitor the band and to protect the RXA port on my 6600. It also receives better than my Hygain 66DX6 beam.
The beam was in the wrong direction but when I tuned it to the correct heading, the signal was a tad better on the vertical. The IR VFA-1 was given to me from a old friend W9SKD (SK) and was in my junk box for years. Searching the internet, I found a 1950’s article in Electronic Experimenters magazine that inspired me to resurrect it.