Not just an replacement, but an improvement!

Description

This datasheet applies for the 5Z3 and 5U4G, which are electrically identical, only have different sockets. 5U4G uses as Octal Socket socket, of which only four pins are used, 5Z3 has an UX4 socket.

This is a direct replacement for the historical 5U4G or 5Z3, but it can not replace 5U4GA or 5U4GB which are different tubes. See Note 4

Note that the Emission Labs tube is somewhat larger size than the original old tubes. Check below at mechanical data, for details. Like most NOS types, also the EML are Slow-Start tubes, protecting the amplifier. The delay time for first function is 2 seconds, and the delay for full current is 7 seconds

We have a standard solid plate tube and a mesh version. These are electrically identical.

For ultra low ripple, it is recommended to use the Lundahl LL1673 dual coil choke, giving higher CMR than a single coil chokes. (See link to circuit diagram, at the bottom of this page).

• Slow Start ( 2...7 seconds)
• Filaments are series connected.
• Two extra large getters
• Each tube is numbered, inside the bulb with a metal Tag
• Two extra large getters, flashing the complete tube bottom
• These tubes are shipped in a high quality dual box
• Tube printing with real gold (metal), red color is burned into the glass
• 5U4G uses a black octal tube base, with four pins. From Yamamoto, the Octal 8/5p socket is recommended. This is an octal socket, but has five pin holes only. It is specially used for rectifiers.
• 5Z3 uses a ceramic tube base.

• See: CIRCUIT DIAGRAM
• See: Note 2

Note 2) To prevent large charge current peaks, the first capacitor (C1) should NOT be larger than 33uF. If the input capacitor is too large, this will result in heavy AC charge current through this capacitor. This is not good for the rectifier tube, and also not for the capacitor lifetime. The AC capacitor current peaks may cause hum radiation into the preamplifier. With the given C-L-C values in table, the rectifier circuit will work best. For filtering, with oversized components, you will have best results by increasing the choke. Do not oversize capacitor C1, this may increase hum. You can choose the choke large as you want. This will have better results with high voltage rectification.

IMPORTANT: SEE RECOMMENDED CHOKE CHOKE CONNECTION SCHEMES

Note 3) Rectifier tubes may under no circumstance carry larger current peaks as what they are designed for. The current peaks are mainly a function of: power supply DC load, first capacitor and transformer copper resistance. The copper resistance for 5U4G and 5Z3 may not be smaller than 170 Ohms. This is very important to check, and too low copper resistance may damage the rectifier, no matter what brand or construction. Use a small series resistor if the copper resistance of the used transformer is too low. If you scroll further down this datasheet, there is a link to a table with historical information about this, for several rectifier types, not only 5U4G.

Note 4) There is common misunderstanding that 5U4G and 5U4GB is the same. However the 5U4GB is a version, with lower internal resistance and higher peak current is allowed. The GB version is not the same tube as the G Version. Replacing 5U4G with 5U4GB may result in higher rectified voltage, so should never be done. Replacing 5U4GB with 5U4G may result in lower rectified voltage, and may result in damage of the 5U4G rectifier.