DIY valve radio kit - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

PJL · 11th Jun 2011, 10:49 am

Looks quite fun to me. R1 bias is needed to provide any kind of anode current/gain at this anode voltage but as soon as there is a signal the grid voltage comes from rectification anyhow.The gain adjustment by adjusting the HT looks a bit weird but I guess it works.

Perhaps my only criticism is it is exploring the extremes of the valve characterstics and not giving much idea of the valves intended use and performance. However, H&S has left little alternative.

neon indicator · 11th Jun 2011, 4:01 pm

Loads of valves work well enough at 48V.

Current limited +90V, +140V or +180V easily obtained from a 45V IC inverter from 6V via diodes and capacitors.

Also H&S doesn't forbid magazines publishing 250V+ Transformer designs either.

11th Jun 2011, 10:49 am	#21
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: DIY valve radio kit Looks quite fun to me. R1 bias is needed to provide any kind of anode current/gain at this anode voltage but as soon as there is a signal the grid voltage comes from rectification anyhow.The gain adjustment by adjusting the HT looks a bit weird but I guess it works. Perhaps my only criticism is it is exploring the extremes of the valve characterstics and not giving much idea of the valves intended use and performance. However, H&S has left little alternative.

11th Jun 2011, 4:01 pm	#22
neon indicator Retired Dormant Member Join Date: Jun 2010 Location: Co. Limerick, Ireland. Posts: 1,183	Re: DIY valve radio kit Loads of valves work well enough at 48V. Current limited +90V, +140V or +180V easily obtained from a 45V IC inverter from 6V via diodes and capacitors. Also H&S doesn't forbid magazines publishing 250V+ Transformer designs either.