Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang
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I've not tried it, but there is a reason for R56 being there. The
resistor and capacitor C70C are there to provide DECOUPLING between the
audio and product detector and the b+/2, NOT just for ripple reduction.
Since only those two stages are connected to this ISOLATED supply, the
current is low, requiring less capacitance for ripple reduction.
In my experience, a 2-B with GOOD electrolytics and an 8BN8 has a very
low residual audio hum. IF you believe the ripple is too high, a better
fix would be to increase the value of C70B and/or R55. IF there is
ripple on B+/3, and C70C has a reasonable ESR, then increasing the
capacitance at C70C is the appropriate fix.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs
www.k4oah.com
Darrell Bellerive wrote:
Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang
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Has anyone done the BB Technical Services Hum modification on their 2-B?
The mod replaces R56 with a jumper and adds extra capacitance to C70. This
adds 25 volts to B+3 but does reduce the ripple.
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