http://users.otenet.gr/~athsam/video_amplifier_2.htm
Useful to amplify and distribute video signals with low noise and without losses. The CA3100 is a fast opamp designed to amplify video signals with low noise and without losses.
http://www.newcircuits.com/circuit.php?id=vid001
This one uses a diode bridge.
http://www.4qdtec.com/cca.html
http://home5.swipnet.se/~w-50719/hifi/qsxm2/
The circuit can serve as a low-noise preamp for spectrum analyzers and other 50 ohm measurement equipment or as an output-power amplifier for signal generators and oscillators.
http://www.edn.com/archives/1997/102397/22di_03.htm
pictures of a linear amp using 5500 Volts on two QB5/1750 tubes at HF for 3200 watts out.
http://geocities.com/nikolic_lj_dragan/Ham/PhilipsQB5.htm