1KW Audio Amp - Tacos discussion

[Karl W4KRL]

One of the websites mentioned in a recent reflector article had a link to a
fellow who bought a 1955-vintage 1KW audio amplifier on eBay. There are nice
pictures at
http://historische-elektronik.piranho.de/Hyperlink%20F/EL6471%201kW%20Groszv
erstaerker.htm and a video of the amplifier performing at
http://www.youtube.com/watch?v=C3_-2fUm6y0
<http://www.youtube.com/watch?v=C3_-2fUm6y0&feature=related>
&feature=related

 

But what caught my interest is his experiment with the 3-phase 50Hz mercury
vapor rectifiers.  Since there are 6 rectifier tubes on a 3-phase supply
this must be a 6-pulse rectifier. See
http://www.youtube.com/watch?v=M_rdZsZasVk
<http://www.youtube.com/watch?v=M_rdZsZasVk&feature=related>
&feature=related

 

What I think is happening here is he is sweeping the input of the amplifier
from 100Hz downward with the amp connected to a dummy load. Various
interference patterns appear in the glow of the rectifiers when the audio
frequency is near some sub-multiple of the 50Hz line frequency. It is
particularly noticeable around 25Hz.

 

This website has a nice explanation of 6-pulse (and other) rectifiers.

http://www.allaboutcircuits.com/vol_3/chpt_3/4.html

 

73 Karl W4KRL

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