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The
VRK and VCK allow the replacement of a
tube rectifier with more reliable solid-state diodes
without the usual increase in plate voltage to the tubes
and capacitors. The tube rectifier has a large internal
resistance compared to a solid-state diode, and produces
a lower DC output voltage. The rise in voltage with
solid-state diodes can unduly stress filter capacitors
and other circuit elements. Attempts are sometimes made
to drop the supply voltage using zeners or other methods,
but these approaches do not allow for easy adjustment.
The
VRK allows the output voltage to be set precisely,
as a percentage of the input voltage, using two fixed
resistors. Current limiting is incorporated to protect
the transformer during fault conditions without affecting
the sound under normal operation. This further assists
in extending the life of filter caps and transformer
windings by limiting inrush currents.
The
VCK uses zener diodes to clamp the output voltage
instead of having it be a proportion of the input.
Transformer
voltages up to 400-0-400Vrms are accommodated, and
solid-state rectification is included in the kit.
Elimination of the tube rectifier improves reliability
and can quiet the amp by removing the hum-injection
point previously provided by the tube. Current up
to 650mA is accommodated.
The
layout uses eyelet construction; the materials and
instructions for this are available in the CCK
Circuit Card Kit.
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Ordering
Information