11-10-2013, 12:05 PM
Something else that you might have to consider is the existing mains transformer, it's probably been designed to run at 60Hz as opposed to 50Hz, that's a 20% difference.
It depends how the transformer is designed, some 60Hz transformers will run at 50Hz without getting excessively hot, but some won't and they will get a lot hotter, maybe too hot and might result in the transformers failure.
There's no easy way round it if the transformer runs hotter than normal under normal current draw conditions due to it being run at 50Hz.
The options are to run it via a frequency converter (expensive?)
Reduce the mains input voltage accordingly, obviously the secondary voltages will be reduced, you can compensate to a certain degree by retaining the solid state HT rectifier that's already installed due to it's lower internal resistance but the valve heaters might be under run.
The other option is to replace the mains transformer with a suitable 240v 50Hz job.
I have a few receivers that were designed for 115v 60Hz, some run not too bad temperature wise but a couple run hot (hotter than one would expect) also have had two that went to meltdown when running them at 50Hz.
There is an explanation in the link below, scroll down the page when it's opened and the info is there.
http://www.allaboutcircuits.com/vol_2/chpt_9/8.html
Lawrence.
It depends how the transformer is designed, some 60Hz transformers will run at 50Hz without getting excessively hot, but some won't and they will get a lot hotter, maybe too hot and might result in the transformers failure.
There's no easy way round it if the transformer runs hotter than normal under normal current draw conditions due to it being run at 50Hz.
The options are to run it via a frequency converter (expensive?)
Reduce the mains input voltage accordingly, obviously the secondary voltages will be reduced, you can compensate to a certain degree by retaining the solid state HT rectifier that's already installed due to it's lower internal resistance but the valve heaters might be under run.
The other option is to replace the mains transformer with a suitable 240v 50Hz job.
I have a few receivers that were designed for 115v 60Hz, some run not too bad temperature wise but a couple run hot (hotter than one would expect) also have had two that went to meltdown when running them at 50Hz.
There is an explanation in the link below, scroll down the page when it's opened and the info is there.
http://www.allaboutcircuits.com/vol_2/chpt_9/8.html
Lawrence.
