UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

PJL · 18th May 2018, 10:16 pm

I'll strip it down and clean it up before prototyping some coils as there are likely to be issues with poor connections/contacts as it is. Aside from the 'gyroscope', the circuit makes sense although the reaction control of a shunt across the aerial coil is a bit odd.

Prototyping the coils would involve:
Wind the primaries, test the resonant frequency and adjust.
Add the secondary to the Anode coil.
Put some valves in and wind the reaction coil to give just enough to bring it to instability across all frequencies.

If it was the same as the Type 31 the original coil set covered 300-500m so only up to 1MHz. I'll go for this for my first attempt. There were no coils sets for any higher frequencies.

I have a couple of questions:
Should I use litz wire?
What turns ratio should I use for the Anode secondary?

18th May 2018, 10:16 pm	#4
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Marconiphone Type 41 I'll strip it down and clean it up before prototyping some coils as there are likely to be issues with poor connections/contacts as it is. Aside from the 'gyroscope', the circuit makes sense although the reaction control of a shunt across the aerial coil is a bit odd. Prototyping the coils would involve: Wind the primaries, test the resonant frequency and adjust. Add the secondary to the Anode coil. Put some valves in and wind the reaction coil to give just enough to bring it to instability across all frequencies. If it was the same as the Type 31 the original coil set covered 300-500m so only up to 1MHz. I'll go for this for my first attempt. There were no coils sets for any higher frequencies. I have a couple of questions: Should I use litz wire? What turns ratio should I use for the Anode secondary?