UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - HT transformers with extra low-I higher-V winding

Radio Wrangler · 23rd Jun 2022, 4:50 pm

If the CRT guesses are on the money, then one of those heater windings is likely extra-well insulated, to be run at cathode potential 1-2kV negative.

In CRT instruments, it's usual to run deflection plates near ground or approaching valve HT for easy direct-coupled drive.

Cathodes rarely rum much more than 2kV negative. CRTs running more total kV usually have a PDA running high positive voltage. So onesy twosy negative cathode volts is common to slow basic CRTs and to fire-breathing stuff from Tek and HP with teens of kV on PDAs.

But if this is mains freq HT, then it'll be all there is. It's unlikely there is an inverter for PDA, because one of those is normally wound for the cathode volts and maybe a bit of overwind into a multiplier for the end voltage.

David

23rd Jun 2022, 4:50 pm	#16
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,874	Re: HT transformers with extra low-I higher-V winding - what were they for ? If the CRT guesses are on the money, then one of those heater windings is likely extra-well insulated, to be run at cathode potential 1-2kV negative. In CRT instruments, it's usual to run deflection plates near ground or approaching valve HT for easy direct-coupled drive. Cathodes rarely rum much more than 2kV negative. CRTs running more total kV usually have a PDA running high positive voltage. So onesy twosy negative cathode volts is common to slow basic CRTs and to fire-breathing stuff from Tek and HP with teens of kV on PDAs. But if this is mains freq HT, then it'll be all there is. It's unlikely there is an inverter for PDA, because one of those is normally wound for the cathode volts and maybe a bit of overwind into a multiplier for the end voltage. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done