Heating U19 rectifiers

[pre65]

How would one heat U19 rectifiers ?

They are 4V @ 3.3A.

Could one 4V CT transformer heat a pair ? If so how would one connect it ?

Sorry if it's a "thicko" question.

[Paul Barker]

Yes, aslong as you are using them on a ctandard centre tapped HT setup, then the cathode potential of each valve is the same, so they can share a filament supply.

As per this diagram, which shows a dual valve, your two valves would be connected in the same way with the two filaments heated in paralell on the same 4v winding. If it is centre tapped all the better, take the B+ from the centre tap. If not centre tapped it wouldn't be the end of the world, take the B+ from the centre of a resistor devider network or from one end as shown in the picture..

Just be sure you parallel the two valve filament connections.



Clearly the filament transformer stands at the full HT potential plus ripple voltage.

[pre65]

Thanks Paul, I sorta thought that might be the way,

[pre65]

As it happens, I now have an individual filament transformer for each U19.

As they are centre tapped, each pair of transformers can be joined at the centre tap to output the HT.

I've still not decided whether to use U19, or 6D22s, but the 30 sec delay of the damper diodes is very useful.

[slowmotion]

The U19s are way cooler. The damper diodes are much more sensible.

[pre65]

The U19s are way cooler. The damper diodes are much more sensible.

If the mains transformer had a 6.3v tap I might have used two U19 and a damper diode for the 30 sec delay.

I've got 8 NOS U19 so it would be nice to use some.

[slowmotion]

Sure , but you only need a small 6,3V trafo ....