Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on August 24, 2014, 04:06:33 am

Title: PT question for Transformers Expert
Post by: kagliostro on August 24, 2014, 04:06:33 am

A friend has build by himself a 620VA PT that is used in an amp who absorbs 460W, the TA after ~20 minutes is at a temperature of 55-60° (Celsius) 131-140° (Fahrenheit)


I consider that as an acceptable functioning temperature, what do you think ?


As to have a fresh during functioning transformer with a load of 460W which will be the right VA of the PT ?


Thanks


K

Title: Re: TA question for Transformers Expert
Post by: sluckey on August 24, 2014, 07:49:28 am

What is a TA?

Title: Re: PT question for Transformers Expert
Post by: kagliostro on August 24, 2014, 07:52:37 am

Sorry Steve

TA = Trasformatore Alimentazione = Power Transformer = PT

TU = Trasformatore Uscita = Output Transformer = OT

Franco

Title: Re: PT question for Transformers Expert
Post by: PRR on August 25, 2014, 09:21:53 pm

> 131-140° (Fahrenheit)

You can hold it for many seconds. It is fine.

Title: Re: PT question for Transformers Expert
Post by: kagliostro on August 26, 2014, 01:47:02 am

Thanks PRR

also I'm thinking it is fine, thanks for the confirm

the 620VA are enough to have a big transformer to transport, so I think it is an acceptable compromise

but I was curious about how big must be the transformer as to be near fresh during functioning

Franco

Title: Re: PT question for Transformers Expert
Post by: kagliostro on August 27, 2014, 03:28:30 am

Quote

A friend has build by himself a 620VA PT ..........

The transformer is a DIY unit

K

Title: Re: PT question for Transformers Expert
Post by: kagliostro on August 27, 2014, 04:01:18 pm

The transformer is an E/I

here you can see it on the left
http://www.diyitalia.eu/forum/download/file.php?id=9933&mode=view (http://www.diyitalia.eu/forum/download/file.php?id=9933&mode=view)

as my friend build more than a PT (and OT) at the moment I'm not sure of which are the exact spec of that PT

as soon as I know it for sure I'll say which are

Quote

EDIT: Here are the spec of the transformer

PT (core 40mmx70mm):

primary 0-220-230V 2A = 0-245-253 spire of 1mm wire
secondary 0-275V / 0-53V / 0-53V / 0-45V 1A = 0-327 / 0-64 / 0-64 spire of 0.73mm and 0-50 spire of 0.8mm wire
secondary 0-50V 200mA = 0-62 spire of 0.40mm wire
secondary 0-12,6V 1.8A = 0-15 spire  - 4 wire in parallel each 0.45mm this was on project but was take off from the real PT
secondario 3.3-0-3.3V 15A = 4+4 spire - 3 wire in parallel each 1.6mm

K