• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

What tubes are used?

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A better picture with all the spec’s:

View attachment 766003

Thanks! That definitely helps. So, there are 3 separate filament windings and 2 of them are dual 5/6.3 VAC.

The AC mains in the Phillipines are 60 Hz./"220" V. Some device, preferably a step down autotransformer, will be needed for that Tango PH-80 to be retained. IIRC, TonyTecson winds "iron". Perhaps he can help with a custom step down that gets the PH-80's primary voltage "perfect".

If a switch to SS rectified B+ is made, plenty of filament/heater current will be available. Clamp mount additional filter capacitance in the opening currently occupied by the rectifier socket.
 
What does the 250-210-0-210-250 Vac 80 mA spec tell us? Does this mean 500 Vac * 80 mA = 40 VA, or 250 Vac * 80 mA = 20 VA?
This way of describing the high voltage secondary, with no other information available, assumes the use of the old classic vacuum dual diode rectifier, and a modest value input capacitor. In this case the 80mA rating is for DC output.

Some liberties can be taken with transformers spec'ed for military or "continuous commercial service" or other fancy devices. But an output of 325-ish DC Volts and 80mA is the intended use, and fine to design to.

All good fortune,
Chris
 
Thanks! That definitely helps. So, there are 3 separate filament windings and 2 of them are dual 5/6.3 VAC.

The AC mains in the Phillipines are 60 Hz./"220" V. Some device, preferably a step down autotransformer, will be needed for that Tango PH-80 to be retained. IIRC, TonyTecson winds "iron". Perhaps he can help with a custom step down that gets the PH-80's primary voltage "perfect".

If a switch to SS rectified B+ is made, plenty of filament/heater current will be available. Clamp mount additional filter capacitance in the opening currently occupied by the rectifier socket.

No problem with the Step down trafo since I have a lot. My problem is the 80ma current. it might not suite other output tubes requirement. Yes I have the option of using solid state diode to add some output current.but the thing is, the wire used for that tap able enough to carry additional current?
 
No problem with the Step down trafo since I have a lot. My problem is the 80ma current. it might not suite other output tubes requirement. Yes I have the option of using solid state diode to add some output current.but the thing is, the wire used for that tap able enough to carry additional current?

From what I see in the photos, the filter choke is not a problem. Perhaps the inductance will drop to 9 H., when somewhat more than 80 mA. passes through it.

SS rectify (for low forward drop) the B+ into a smallish 1st filter capacitor. Make the value of the filter 1st cap. just big enough to keep the rail voltage up, which will allow a bit more than 80 mA. of B+ to be drawn. The choke will "isolate" the power trafo, diodes, and 1st filter cap. from the reservoir capacitor. A large valued reservoir cap. will keep residual ripple acceptably low. You can entertain the notion of a CLCRC filtered B+ rail.

The O/P trafo lacks the magnetic headroom needed to support global NFB. Triode wired nV6 finals running 35 mA. of "idle" current should leave you reasonably well placed. I guesstimate a 7 W. power O/P.
 
Does anybody know the specs of the Input Transformer? it Lux 3657P. i've search google and i was able to find images only and the 3656P . If Driven by 37 or 56 triodes on this amp so it might have more than 5 ma of primary current? how about secondary and most especially the turns ratio?

I might burn the IT if feed with excessive current?
 
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Joined 2011
It’s a 1:3 step up IT, likely with an air-gap, so no need to worry about the DC current (within reason of course).

179489FA-7B2F-496C-AD98-8BD70C08AD2D.jpeg
 
Thanks again Jazbo.

Now its clearer for me to do the projects with option as per owner request. He wants to maximize the OPT around 8-10w max with PP triode but the Power trafo will not be sufficient at 0nly 80ma capability. pentode and tetrode will do but on Triode its I think not doable. Any Idea?
 
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