artificial center tap grounding

[Ed de Jager]

Hi,i am wondering,since my PT doesn`t have a center tap for the heaters i am using 2 100Ohm resistors to ground.
What is the best way;use the groundbus on the pots or use another location like the PT or is there a better location?

Thanks very much in advance!

Ed

[Normster]

I don't know if it's the best way, but I've seen at least one Dumble photo with the 100R's grounded at a tab on the power tube mount screw.

[Ed de Jager]

Thanks Normster,i never saw that before but it actually seems a convenient way to mount them.
I thought about mounting them on a solder lug at one of the legs of the PT and i guess i have to make up my mind now.

Ed

[groovtubin]

Thanks Normster,i never saw that before but it actually seems a convenient way to mount them.
I thought about mounting them on a solder lug at one of the legs of the PT and i guess i have to make up my mind now.

Ed

[Bob-I]

Since I've been building a SLOClone I've been looking at some of the discussion on the SLOClone forum. Soldano uses straight 3/64" brass rod inserted through the socket pins for heaters on the 9 pin tubes. The power tubes have the wires running parallel in a straight line over the sockets. The connected between the 2 is twisted and the connection to the PT is twisted.

Many of the folks use a modified faks CT there. I've yet to try this so the jury's still out.

[img:874:474]http://i18.tinypic.com/29zy5gj.jpg[/img]

Note the the 2 100R resistors are connected to a 1M and 100K||47uF/100V. The 1M is in turn connected to the second node on the power supply. The 1M/100k is a voltage divider to lift the heater CT above ground by maybe 50V.

Interesting, I'll be trying it soon.

Here's the pics of my SLOClone so far for anyone interested..... click on the thumbnail to get to the webshots page.

[IMG32]http://thumb9.webshots.net/t/59/559/9/12/73/2781912730033762409BqNZTH_th.jpg[/img]

[Bob-I]

Here's some pics of a SLO where you can see the heater wiring closely.

[img:640:480]http://sloclone.yesterdaysrevolt.com/images/126.jpg[/img]

[img:640:480]http://sloclone.yesterdaysrevolt.com/images/125.jpg[/img]

[Funkalicousgroove]

On a Dumble they are located on pin 7 of tube5 and pin 2 of tube 4.

[groovtubin]

Here's some pics of a SLO where you can see the heater wiring closely.

[img:640:480]http://sloclone.yesterdaysrevolt.com/images/126.jpg[/img]

[img:640:480]http://sloclone.yesterdaysrevolt.com/images/125.jpg[/img]

Bob, i`ve seen a REAL early version of a SLO w/CARBON COMP screen grid resistors!!!! wish i still had that photo, it was cuhl!!

[DaveBo32]

Normster,
The artificial CT only needs to be executed once? If I have a CT should I ground it or should I tie it off and use the 2 100ohms to ground? I heard it helps with eliminating hum more effectively. If I use the 2 100ohms to ground, do I only do this once not repeatedly?

Thanks,
Dave

[Bob-I]

Normster,
The artificial CT only needs to be executed once? If I have a CT should I ground it or should I tie it off and use the 2 100ohms to ground? I heard it helps with eliminating hum more effectively. If I use the 2 100ohms to ground, do I only do this once not repeatedly?

Thanks,
Dave

If you have a CT use it and skip the 100 ohm resistors.

[DaveBo32]

Thanks Bob-I. I'm going to use the CT.