Just as TV sweep tubes were never intended for RF service, this is also not.
http://www.toshiba.com/taec/componen...c//70/9267.pdf
But, it works.
Look at the voltage ratings! excellent!
This transistor will present around 140 ohms impedance, as opposed to around 5000 for a 6JS6C tube, so some very minor adjustments of the circuits are needed.
A pair of 6JS6C tubes runs around 3000 ohms, a pair of 2SC5588 are around 100 ohms.
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look's gud up to 32Mhz!!