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EML 80
Mesh Version

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Did you know? Emission Labs was the first company to re-introduce the 80 again, in the year 2010.


Guarantee

The first owner can register the tube at the Emission Labs website, to participate in the 5 years guarantee program.

Description

The 80 was originally intended for radios or small amplifiers. This diode is a somewhat smaller version than the 5U4G, intended for lower DC output current, and lower voltage. The maximum value for the capacitor is 20uF, which is lower than with 5U4G, however since the 80 is intended for maximum 135mA, the value of 20uA is sufficient. Output ripple is also lower because of higher plate impedance of this tube. It must be said if you are working at the lower current such as below 135mA, the 80 is a very good choice.

For ultra low ripple,  it is recommended to use the Lundahl LL1673 dual coil choke in low CMR configuration. In this configuration, there is virtually no field radiation from the choke. (See  link to circuit diagram, at the bottom of this page). 

Features
  • Hard metal filaments (Note1), series connected.
  • Each tube  is numbered, inside the bulb  with a metal Tag
  • Hand blown, Globe shaped glass
  • Two extra large getters.
  • These tubes are shipped in a high quality dual box or single box for rectifiers.
  • Tube printing with real gold (metal),  red color is burned into the glass. 
  • Gold plated pins,  black ceramic UX4 socket.  (White bottom).  Ideal for the YAMAMOTO tube sockets.
Typical application notes below here, applies for 80 and the 274 tube as well.


Type 80
Large Image
Plate Detail
Socket

 

.
Filament Ratings
Filament Voltage
5 Volt (AC or DC)
Tolerance on filament voltage
5%
Filament Current 
2 Ampere 
.

Maximum ratings

IMPORTANT: Please read the notes at the bottom of this data sheet

AC input voltage
350Volts
DC output current
125mA
Copper Resistance of transformer minimum value. Add normal resistor if copper resistance is too low. (so if you have 120 Ohms, you need to add 80 ohms or more)
200 Ohms
First capacitor,  connected to plates
20uF  max
.
..
80 Mechanical Data

Size including Socket
(but excluding pins)

140 x 58 mm 
5.5 x 2.3 Inch 

Tube weight:
130 Gram
Shipped weight for a single boxed tube:
400 Gram

Note 1) Good care should be taken when making the design of any DHT rectifier. It must be prevented to have strong current peaks, through the first capacitor, because consequently this flows through the tube anode, and transformer windings as well. The transformer will produce mechanical hum by this, most specially if windings symmetry fails. Also the tube will suffer. For this reason, the first capacitor (C1) should never be larger than stated in this data sheet.   The mechanical transformer hum, and also tube current peaks are greatly reduced by smaller capacitor values, and use higher choke values instead. Although higher capacitor values are at lower cost, using lower capacitors and higher chokes values instead, is always more satisfactory in the end. The result will be: Lower transformer hum, less electrical field radiation into the pre-amp, and more lifetime from the rectifier tube. This is why we recommend using largest chokes. From Lundahl, high value chokes are achievable at the same price as HiFi capacitors, like from a Mundorf or Black gate. So we have to go back to the roots, and use high quality, large value chokes, like in the old days of radio design. For best ripple suppression, increase the choke to any value you need, or even use a C-L-C-L-C circuit, as also advised in the historical RCA data sheet.
Note 2) Higher capacitor values up to 20uF can be used, if you work at lower voltage and lower current than maximum. This will be the case for instance with smaller amplifiers, such as using the 45 tube.
Note 3) As a rule of thumb, high voltage power supplies are best build with large size chokes, specially at high output current, whereas low voltage power supplies can be build more easily with large capacitors.
Note 4) Windings symmetry is needed with HV transformers to prevent hum. A HV winding with center tap, requires FOUR separated HV windings inside the transformer, which are arranged for the end user as TWO windings which are in series. It is remarkable to see, this is widely unknown today by many transformer manufacturers. Also this is more expensive. So often, they build tube rectifier windings only from two internal windings, and not FOUR windings as needed for tube rectifiers. However we have a tube data sheet here, no transformer construction manual, so we can not explain this in more detail.


SOME DESIGN NOTES FOR POWER SUPPLIES.

Design note-1

Design note-2


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