Mercury PT filament wiring question

[oldpicker]

Thanks for helping a newbie in advance. Do I need to use the green wires for the filaments and are they 3.15 volts each or 6.3 volts each and do I ground the green/yellow center tap or just not use it. This is for a OTS 50 watt.

http://i168.photobucket.com/albums/u187 ... one002.jpg

thanks
Dennis

[Structo]

3.15v each, center tap to ground.

[oldpicker]

Thanks Structo. I thought I had it right but sure didn't want to short the Pt right from the first power up.

It was posters such as yourself that encouraged me to make the plunge. I have built a few JTM type amps but have always chased the sound of the Dumble amps. Thank you and the many contributors that keep us newbies trying to unravel the tone.

Dennis

[ampdork]

If you use the center tap just be sure you don't use the balance resistors off the filaments.

[oldpicker]

Thanks Ampdork. I thought I read something about that. No balance resistors on my schematic.

Dennis

[Structo]

I always wanted to try the 100 ohm resistors vs the center tap to see if I could hear the difference.
But never did because I am essentially lazy.

Supposedly the resistors make a better center tap because they are a closer match than the center tap is.
You might try measuring the resistance between the center tap to each lead on the heater winding just to see how balanced it is.

[ChrisM]

I always wanted to try the 100 ohm resistors vs the center tap to see if I could hear the difference.
But never did because I am essentially lazy.

Supposedly the resistors make a better center tap because they are a closer match than the center tap is.
You might try measuring the resistance between the center tap to each lead on the heater winding just to see how balanced it is.

Not sure if that would work.

One winding is wound on top of the other (not touching of course). This means it has a large diameter and in turn more wire is used for the windings. More windings means more resistance. So I would say that is not an accurate way to check balance.