I'm a regular visitor of:
the Dutch Old Radio forum
www.nfor.nl (only tube and hybrid sets)
the Dutch transistor forum
www.philipsradios.nl/forum (only transistor and hybrid sets)
the Dutch mfbfreaks.com forum
forum.mfbfreaks.com (hifi, mostly Philips 1970's and 1980's)
other fora I visit include:
www.buizenradioclub.nl
www.radiomuseum.org