For old times sake: a grid dipper / RF generator with tubes.
Prototype
The prototype was build with a variable capacitor from a old MW radio.
Maximum frequency is 48MHz.
A ferrite antenna from an old radio (see prototype picture) covers
560 to 1640 KHz.
Final
The final griddipper uses the smaller EC92 iso the ECC85 of the prototype.
Other differences in component values were dictated by the contents of
the junkbox.
The 1 ohm resistors are used to get a 6.3 V heater voltage.
Archive containing the Xcircuit files (encapsulated postscript).