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-   -   Converting 6.3V to 6.3VCT Quick questions (http://www.diyaudio.com/forums/tubes-valves/85163-converting-6-3v-6-3vct-quick-questions.html)

Trout 22nd August 2006 08:15 PM

Converting 6.3V to 6.3VCT Quick questions
 
I Grabbed up a couple Hammond Transformers for a project not noticing the lack of a CT on the 6.3V wind.

I saw that its possible to use a pair of resistors to simulate the thing, But I am not certain of the resistor value needed nor did it say the wattage resistor to use. Would this be similar to a fixed hum balance pot?

If this is correct, it should be mounted very close to the transformer? or can i move it a few inches away and mount it on the bayonet style pilot lamp bracket?

Trout

http://home.mchsi.com/~sara.richter/CT_trick.JPG

Gatto Murr 22nd August 2006 09:45 PM

Re: Converting 6.3V to 6.3VCT Quick questions
 
100 ohm, 1 watt each are ok.
Resistance value is not so critical here, perhaps a potentiometer (250-300 ohm) would be better (can be set to minimize hum - the proper position being not necessarily in the middle.

Where to put the two resistors (or the pot): well you have better to experiment. Avoiding ground loops is the target.

More important: use tightly twisted wires to connect the filaments.

regards, Piero

Trout 22nd August 2006 11:12 PM

Re: Re: Converting 6.3V to 6.3VCT Quick questions
 
Quote:

Originally posted by Gatto Murr
100 ohm, 1 watt each are ok.
Resistance value is not so critical here, perhaps a potentiometer (250-300 ohm) would be better (can be set to minimize hum - the proper position being not necessarily in the middle.

Where to put the two resistors (or the pot): well you have better to experiment. Avoiding ground loops is the target.

More important: use tightly twisted wires to connect the filaments.

regards, Piero

Hey,, Thanks for the quick reply, I found another website with the same info after I posted the question, so I guess I am on the right track. Looks like its ok to mount them on the pilot lamp holder, Common practice on old tweed fenders when removing the death cap and upgrading the power cord.

Trout

Enzo 23rd August 2006 12:37 AM

They don't really have to dissipate any power, not much current flows, they are just references. I use 1 watt or even 5 watt just so they will be mechanically sturdy. 8 million Fenders can't be wrong. Mount them to the pilot lamp socket and ground them nearby. In guitar amps it doesn't really matter much where they are connected to the 6v wires.

AJT 23rd August 2006 06:04 AM

Re: Converting 6.3V to 6.3VCT Quick questions
 
Quote:

Originally posted by Trout
I Grabbed up a couple Hammond Transformers for a project not noticing the lack of a CT on the 6.3V wind.

I saw that its possible to use a pair of resistors to simulate the thing, But I am not certain of the resistor value needed nor did it say the wattage resistor to use. Would this be similar to a fixed hum balance pot?

If this is correct, it should be mounted very close to the transformer? or can i move it a few inches away and mount it on the bayonet style pilot lamp bracket?

Trout

http://home.mchsi.com/~sara.richter/CT_trick.JPG

that is ok, i did not stop there, from the juntion of the two resistors i hooked up a 47k 1watt resistor and connected it to ground, also on that junction i hooked up a 150k 2watt resistor and connected the other end to a 300v B+. hum completely disappeared!


:D :D :D


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