When he says full wave silicon circuit - im guessing he is talking about a solid state full wave rectifier that would output noisy DC..
Why is he running DC into the input side of a 5U4? The 5U4 is a full wave rectifier....
What am i missing here...
A few basic facts maybe unknown to most:
1. The 'silicon' rectifier 'in-socket' replacements for the tube rectifiers were well known for the noise they generated.
2. 500-0-500 secondary to the silicon was fine but that would be outside the normal operating range for all but a few 5U4GBs.
3. The 5U4GB was the 'high vacuum' variety. There should be less chance of making the tube go bad due to misuse. Addition differences make it oranges & apples to the 5U4.
4. Thermionic emission is normally the result of heating the cathode from the heater filament. Here, the heater filament was also the cathode. An excessive reverse bias to the 5U4GB (with no heater power) would cause thermionic emission to be secondary instead of primary.
5. If you reverse almost everything familiar in a full-wave rectifier and backward-feed another full-wave rectifier you get the following:
a) center tap 500-0-500 secondary
b) each '500' wire connected to the cathode of a 'silicon' rectifier (why mention it was silicon? Even then, it was assumed to be so and not mentioned)
c) the anode of each silicon rectifier connects to an anode of the 5U4GB
d) in one direction - the silicon is overdriving the tube - as the silicon replacements always did - and with a noisy wave. As a rule of thumb; a power supply using silicon rectifiers will develop an HT voltage -under load- that is roughly 1.2 times the RMS voltage delivered by the transformer. No-Load can be much higher.
e) in the other direction the tube is doing the rectifying also placing the silicon in a reverse bias (noise generator anyone?)
That would be valid thoughts while thinking noise generation is the key.
I think this lesson was more than an analogy. I think it is an actual way to see the most basic operating principles of a TPU.
The above is not a bad thing to test but one thing isn't considered. Why are tubes an easier starting point?
My opinion:
Tubes are the easiest way to convert energy in the transverse form to compression waves then back again. How many solid state devices can do that?
Why harp on compression waves again? Because, there is no gain from two waves meeting unless they are both compression waves. Then, is the only time superposition provides real gain. (yes, I know. 'Compression waves' is an oxymoron in the eyes of the classicist. Never the less, they exist in waveguides, the Earth's waveguide and plasma chambers.).
The biggest mistake being repeated is folks try to jump right to SS thinking the conversion state was upgraded by doing it in the SS. Bad mistake. The upgrade was to move the conversion from the tubes to the coils. The controls are just controls.
My opinion - for a late Sunday evening.
Cheers Folks. Have a good week!
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Topic: rectifier into 5U4? (Read 74408 times)
