[AMPS] In-rush Protection
Roy Koeppe
royanjoy@ncn.net
Wed, 20 Jan 1999 13:59:59 -0600
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The in-rush protection scheme I use is the simplest, cheapest, easiest =
and (best?) of all. It requires NO modification whatever to the amp. And =
it also provides in-rush protection to the HV diodes and cap bank as a =
free bonus. It starts everything gently at half voltage, and can be used =
at shut down time to cool hot tubes. The only requirement is that your =
amp must use zero-bias, triode tubes such as 3-500Z, 572B, etc.
=20
OK, you need ONE component: a DPDT hefty toggle switch or equivalent. =
Run the moving, common contacts to a female power plug cord receptacle. =
Your amp plugs into this "adapter cord." Another cord runs from one =
fixed set of contacts to your 120 VAC wall outlet. One last cord runs =
from the other fixed contacts to your 240 VAC outlet.=20
=20
Get the picture? You always turn on the power switch on your amp while =
the toggle is set in the 120 position. Then, after the tube(s) warm up =
to half brightness, (and your B+ reads half normal) you simply switch =
the toggle up to the 240 position. Power down is accomplished in reverse =
order--you can cool down a few minutes, if you like before shutting off =
the main switch on your amp. Simplicity is ingenuity, a wise man once =
told me. There's very little interest here for Mr. Murphy.
=20
73, Roy K6XK/0 Iowa Outback
=20
=20
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<DIV><FONT face=3DArial size=3D2><B>-----</B><BR><BR></DIV></FONT>
<DIV><FONT color=3D#000000 size=3D2>The in-rush protection scheme I use =
is the=20
simplest, cheapest, easiest and (best?) of all. It requires NO =
modification=20
whatever to the amp. And it also provides in-rush protection to the HV =
diodes=20
and cap bank as a free bonus. It starts everything gently at half =
voltage, and=20
can be used at shut down time to cool hot tubes. The only requirement is =
that=20
your amp must use zero-bias, triode tubes such as 3-500Z, 572B,=20
etc.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>OK, you need ONE component: a DPDT hefty toggle =
switch or=20
equivalent. Run the moving, common contacts to a female power plug cord=20
receptacle. Your amp plugs into this "adapter cord." Another =
cord runs=20
from one fixed set of contacts to your 120 VAC wall outlet. One last =
cord runs=20
from the other fixed contacts to your 240 VAC outlet. </FONT></DIV>
<DIV><FONT size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>Get the picture? You always turn on the power switch =
on your=20
amp while the toggle is set in the 120 position. Then, after the tube(s) =
warm up=20
to half brightness, (and your B+ reads half normal) you simply switch =
the toggle=20
up to the 240 position. Power down is accomplished in reverse order--you =
can=20
cool down a few minutes, if you like before shutting off the main switch =
on your=20
amp. Simplicity is ingenuity, a wise man once told me. There's =
very little=20
interest here for Mr. Murphy.</FONT></DIV>
<DIV><FONT size=3D2></FONT> </DIV>
<DIV><FONT size=3D2>73, =
Roy =20
K6XK/0 Iowa Outback</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
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