Hi Guys.
I thank you all for your answers. I am now much wiser. :-)
I normally "dabble" with old tonewheel Hammond organs which of course use valves, although these are still manufactured and easily available.
I do have a working GE L643 radio though:
http://www.radiomuseum.org/r/general_el_l643.html .
It belonged to my late Father and I had it professionally serviced and re-capped around 10 years ago. It doesn't get used much as it's only a short wave radio and there ain't many stations still broadcasting on those frequencies.
To mibn2cweus I can only say, " )-: ¡ɯǝlqoɹd ǝɯɐs ǝʌɐɥ I ˙dɐɥɔ plo 'lǝǝɟ noʎ ʍoɥ ʎlʇɔɐxǝ ʍouʞ I "
Stay good!
Cheers.
Mike C.