Takes much greater precision and quality of components and workmanship to manufacture an amplifier to work 50 MHz and above.
The higher you go in frequency the higher the tolerance of the build...
Even the length of the hook-up wire between components becomes a major factor.
All the Best
Gary
Henry Radio still produces fine solid state UHF and VHF amplifier$, are made in the great US of A and out lasted Tokyo Hy-Power, haha.
http://www.henryradio.com/amplifiers.html