| Created: 24/09/05 | Last update: 22:03 05/03/07
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A European Classic.

Elektor March 2005 was an audio issue and featured two amps, one transistor, the other valves.

The valve amp is basically a Hi-Fi Monoblock, but the valves used are of interest and new one to me.

Telefunken apparently made these for years before selling their plant to China who are now belting them out, so expect to see these come to an amplifier near you sometime soon.

While these have the same pinout as 6L6's and KT88's they differ in several respects. A pair can make 130 watts at 6% THD in Class AB1. They are a genuine beam power tube and like the 6DQ6 are sensitive to screen grid voltage which must be enough and stable. They are higher gain than most output bottles and require a lower grid resistance to ground.

Heater voltage Uf 6.3 6.3 V
Heater current If 1.5 1.9 A
Maximum anode voltage Uamax 800 800 V
Maximum cathode current Ikmax 150 180 mA
Maximum anode power dissipation PVmax 25/27.5 40 W
Maximum screen grid power dissipation PVg2 8 8/12 W
Screen grid current Ig2 11/22 5/25 mA
Maximum screen grid voltage Ug2max 425 450 V
   in class AB operation 425 350 V
Grid bias voltage Ug1 -39 -24 V
AC grid driving voltageUg1AC 23 18 V
Transconductance S 11 13 mA/V
Internal resistance Ri 15 20 kohm
Maximum grid leak resistor Rg1max 700 100 kohm

No plate-to-late loads are given.

If you are interested in applying these valves you will need to do your research because they are a little out of the ordinary.

Ref: Elektor March 2005,

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