816a HG Rectifier Voltage Drop

[Gungnir]

This may seem like a dumb question, but would two 816a rectifiers in full wave configuration drop 15 or 30 volts?

 

[Alan4411]

I think I understand the question.

If the 816 spec is 15 volts drop per tube, then the the full wave configuration using 2 tubes will still be 15 volts.

Each half of the cycle has a loss of 15 volts, so when combined at the 'cathodes' the single cycle loss is still only 15 volts.

A full wave bridge configuration (4 rectifiers) would / will have a loss of 30 volts as there are 2 rectifier losses per cycle.

 

[Alllensoncanon]

For an directly heated MV rectifier, I wouldn't know nor wanted to hook them up in a full wave bridge configuration. Sounds dangerous . For silicon diode, there is one forward voltage drop (FWD) for each +- rail, = 2X FWD.

 

[Alan4411]

Agreed, it was included by way of an example...
I thought the 'real life' implementation was rather ummm, impractical.

 

[Gungnir]

I think I understand the question.

If the 816 spec is 15 volts drop per tube, then the the full wave configuration using 2 tubes will still be 15 volts.

Each half of the cycle has a loss of 15 volts, so when combined at the 'cathodes' the single cycle loss is still only 15 volts.


A full wave bridge configuration (4 rectifiers) would / will have a loss of 30 volts as there are 2 rectifier losses per cycle.

Ah, I see, thanks for the help!

 

[Kay Pirinha]

For an directly heated MV rectifier, I wouldn't know nor wanted to hook them up in a full wave bridge configuration. Sounds dangerous . For silicon diode, there is one forward voltage drop (FWD) for each +- rail, = 2X FWD.

...which basically is possible and actually has been done yet multiple times. You need three separate heater windings for the four rectifier tubes. And it isn't dangerous at all, unless you're going to break the glass envelopes .


Best regards!

 

[Eli Duttman]

And it isn't dangerous at all, unless you're going to break the glass envelopes

Sooner or later, an envelope will break. When that happens, a very nasty toxic mess has to be dealt with. If you're going to "play" with Hg vapor rectifiers, keep a canister of powdered sulfur on hand. You sprinkle the sulfur on any Hg that gets loose. Mercuric sulfide (HgS) quickly forms and that's relatively safe. HgS is extremely insoluble in water. Even boiling nitric acid will not attack HgS. It takes burning/roasting or aqua regia (HCl + HN0₃) to decompose HgS.

 

[hpeter]

This may seem like a dumb question, but would two 816a rectifiers in full wave configuration drop 15 or 30 volts?

ofcourse 2*15

i prefer fast si hv diodes in - side.

 

[12E1]

No - that is a full-wave bridge rectifier which uses four diodes. A full wave rectiver using two valves only has one valve conducting at any one time. This was already pointed out above. But see here as well if not clear...

Full wave rectifier vs full wave bridge rectifier - Electrical Engineering Stack Exchange