Scope CRT current
I'm having another look at my Sun engine analyser. It has a scope for displaying various ignition wave-forms. The mains transformer supplying all the voltages has long since died and scrapped.I have one that will provide the -1.2kV and the heater allowing the heater to float. The other potentials , focus and astig are catered for with another transformer. The final anode runs at 2kV This has been a problem! I now possibly have a solution. I have rescued from work a PSU that was originally used to supply an ion pump. It has an EHT PSU as a single block device, 12v in and 4kV out. The data sheet shows the o/p to be directly proportional to the input voltage so to get the 2kV needed I supply it with 6v. All good. The EHT block is rated at 0.75mA at 4kV. nowhere can I find any indication of what a small tube will need as eht current. can anyone suggest a ball park figure for tube current?
The tube is a RCA 4490 and the EHT block is an EMCO E40
Malcolm
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