selenium HV rectifier

[wa2ise]

I wouldn't have thought that any TV set would have used a selenium rectifier for the high voltage. Selenium rectifiers tend to be leaky and lossy. And tube HV rectifiers are fairly cheap, but do require filament power, which is always gotten off the flyback circuit. Submini HV rectifiers, IIRC the 5642, are small and can do up to about 10KV, not enough for color TV though.

[DaveWM]

its for focus, I know the title is missleading

[dieseljeep]

Originally Posted by wa2ise

I wouldn't have thought that any TV set would have used a selenium rectifier for the high voltage. Selenium rectifiers tend to be leaky and lossy. And tube HV rectifiers are fairly cheap, but do require filament power, which is always gotten off the flyback circuit. Submini HV rectifiers, IIRC the 5642, are small and can do up to about 10KV, not enough for color TV though.

Some of the early Japanese color sets used the 5642 as the focus rectifier. Only one chassis model RCA made used the selenium focus rectifier. That was the CTC15, the model everyone else cloned. All the large sets, before it and after it had focus rectifier tubes. Tells you something, doesn't it.