"Jeff Wisnia" wrote in message
...


Ralph Mowery wrote:

The modern stuff probably will. I have an old amp that has some
expensive
tubes in it and the main cause of bad tubes is burnt out filiments. They
are critical as not to go over 5 volts. The amplifier is about 45 years
old.

FIVE volts? Did you mean maybe 6.3 volts?

Well, maybe filiments run at 5 volts, but filaments were specified to run
at 6.3 volts, commonly referred to as 6 volts.

See: http://www.ampage.org/td/vtd6v6.html

Jeff


No, I ment FIVE volts like it says. They are 3-500Z tubes used in a Drake
L4b amp. Don't recall the prices without looking them up, but somewhere
around $ 150 to $ 200 per tube.

Over the years filaments have been all the way from about 1.5 volts to 117
volts with many different voltages between. This is just the common
household equipment such as radios and TV sets. Even the old "all American
5" AM radio had a 35 and 50 volt tube in it. Even in the years the 6.3
volt tubes were common, it was not unusual to have a 5 volt tube in the
equipment with its own 5 volt winding on the transformer. Usually it was
the rectifier tube.