Hi Mark:
The 3-400 and 3-500 are pretty much interchangable and were both sold with
the early Drake L4 and L4B amps. The 3-400 is a great tube and actually
drives easier than the 3-500. However, they are much more difficult to get
used.
Both types of tube put out about the same amount of power - since it is
usually other factors that control power output rather than plate
dissipation. In my Swan amp, I actually get more power output with the
3-400 because it drives easier and my KWM-2A has only 65 watts output
(adjusted for minimum imd).
Some amplifiers designed for the 3-400 cannot accept the extra height of the
3-500. I had a Tempo amp that would only accept the 3-400.
There is a bit of difference in bias voltage, so if the resting current is
too high, you will need to install some bias diodes.
Be sure to remove high voltage if you are on the telephone, when you change
tubes, as electrocution is rather frightening to the person at the other end
of the telephone line.
73, Colin K7FM
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|