The Minimalist Superhet Radio project.

[Geordie McBoyne]

Today, the beat up SenTerCel metal HT rectifier has been removed. The old rectifier will be substituted with a 6X5GT valve. Although designed as a full wave rectifier the 6X5GT was often used as a half wave rectifier, think of the KB "toaster" FB10.  A 1 1/8" Q-max cutter was used to make the hole for the octal valve socket. Because of the introduction of the new valve holder many of the under chassis components will be repositioned. One not particularly nice feature of the circuit design is the position in the circuit of the single pole on-off switch, it is only the in neutral side of the mains which is switched, nasty! Switch the set off and the chassis becomes live. However, a replacement double on-off switch was fitted some time in the distant past so the now the mains will be fully switched and later on a mains fuse will incorporated in the mains supply circuit.                               

I'm sure the existing mains transformer will cope with the additional 0.6amp heater current demanded by the 6X5GT. Total heater current including the 6X5 is 1.7amps. The dial lamp is supplied from a separate winding on the transformer. 
The large 6V6G output valve has been substituted by the much more compact 6V6GT. The 6V6 has a modest slope of 4.1mA/V, in the development mule the output valve is an UL84 has the much higher slope of 10.5mA/V.   

Geordie McBoyne.