Buck Transformer ? NOT HATT RELATED

[MikeP]

I'm restoring some tube audio equipment that was designed to run at 117- 124VAC. our voltage varies from 125-130 which puts things like heater voltage too high. I have a couple of variacs which can do the job, of course, but I use them for projects and don't want to leave them "permanently attached to the amp/preamp in question.

Basically, what I need is a Xformer to drop the voltage 5-6 volts but all the searching I have done comes up with Xformers that drop line voltage down to 24/36/48V. I'm sure I must be searching incorrectly but I know there are folks here that are familiar with such stuff so some guidance/suggestions would be welcome.

I seem to be getting more and more into tube gear of various types for some reason and my two variacs are always "busy" with something else and have to be unplugged and shifted to alternate duty.

Or should I just by a few more Variacs?

 

[Boatsb]

I'm restoring some tube audio equipment that was designed to run at 117- 124VAC. our voltage varies from 125-130 which puts things like heater voltage too high. I have a couple of variacs which can do the job, of course, but I use them for projects and don't want to leave them "permanently attached to the amp/preamp in question.

Basically, what I need is a Xformer to drop the voltage 5-6 volts but all the searching I have done comes up with Xformers that drop line voltage down to 24/36/48V. I'm sure I must be searching incorrectly but I know there are folks here that are familiar with such stuff so some guidance/suggestions would be welcome.

I seem to be getting more and more into tube gear of various types for some reason and my two variacs are always "busy" with something else and have to be unplugged and shifted to alternate duty.

Or should I just by a few more Variacs?

Use a 18 ga 100 foot extension cord. Put a load on it and see what you get as drop.

Measuring voltage on a circuit with no load can give you the wrong impression.

Also where are you getting 125 to 130 volts?

 

[MikeP]

Use a 18 ga 100 foot extension cord. Put a load on it and see what you get as drop.

Measuring voltage on a circuit with no load can give you the wrong impression.

Also where are you getting 125 to 130 volts?

Our normal wall outlet VAC here (Mexico) is 129-130) That is measured at the outlet - no load. 130 is the "standard" wall voltage in Mexico. It's hard on vintage equipment - at least US equipment - that was designed for nominal 117VAC. For example, with 130VAC input, the voltage at the tube heaters in my Ampex 351's tape recorder preamps is higher than the max voltage spec for the tubes. So the one of the Variacs is permanently connected to that unit with the voltage to the preamps regulated at 120.

I'll be moving some of this equipment to San Antonio TX in just a few days and will be doing some VAC check there - probably won't be an issue back in the US. In NY it was around 123 typically though it varied at the house based on seasonal air conditioner use.