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question on 5Y3 rectifier substitutes

What is wrong with 5Y3 tubes?

What extra specs or capability do you need for a circuit that is already proved to work well?
Or is this a factor of price or availability?

For those who do like the 5Y3, only because it does not have delayed B+ . . .
Then add an additional 6.3V filament winding (a rectifier dedicated winding, not for the other tube filaments), and . . .
Then connect a 0.65 Ohm 5 Watt resistor in series from one end of the 6.3V to the 5Y3 filament, and the other end of the 6.3V to the other end of the 5Y3 filament.
That makes a Slow Start B+.

Have Fun!
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5Z3 3.0 amp filament (+50% more filament load on the power transformer versus 5Y3 2.0A filament).
5Z3 58V drop, but at 225mA (versus 60V at lighter load current of 125mA 5Y3); slighty more B+ volts with 5Z3 than 5Y3.

5Z4 20V drop at 125mA (-66% versus 5Y3), You get 40Volts more B+ with 5Z4 than 5Y3.

Then, take a look at the tube curves versus the input capacitance, the performance is different too, some curves have 4uF, 10uF, etc.
If you are using 50uF or more first capacitors you will need Lots of series resistance to the plates.

All rectifiers are equal, but some rectifiers are more equal than others.
$aving money i$ not alway$ a good idea.

Eurotubes.com ha$ 5Y3S for $23.
Or, Purcha$e the more expen$ive NO$.

No free lunches here.
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5Y3 Substitute?

5Z3 requires a 4-pin socket.

5Y3 requires an Octal socket.

5Z4 requires an Octal socket.
It has an indirectly heated cathode, so it is a slow start tube.

My Post # 2 above makes a 5Y3 into a slow start rectifier circuit.
Just add an Extra Separate 6.3V winding, and a 0.65 Ohm 5 Watt resistor (a 10 Watt resistor will run cooler).
thanks for the input. i should have referenced the reason for my inquiry. a friend of my Son has inherited a collection of tubes through his great grandfather's tv repair business and forwarded an offer to me to take some of the tubes- specifically some of the rectifier tubes- free as a thank you for some help i had given him several years back. as the amp i'm currently working on came with a 5y3 i thought it would be an opportunity to try some alternate tubes if compatible. i am hoping to get with him and perhaps purchase the rest of the collection if i can.