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:
R8B and external power supply
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14
February 23rd 05, 03:08 AM
starman
Posts: n/a
wrote:
No, but I don't think I need to. The noise is *only* there when I use
the external power supply.
I don't really mind using the Drake's internal power supply, but I
suspect an external supply would cut down, at least a bit, on the
occasional snaps and pops that come through the AC line.
Steve
First, the diodes in your power supply may not have any RF bypass
capacitors across them. These are intended to suppress the switching
transients caused by the diodes, which can make a humming or buzzing
noise in the radio, especially when it's tuned to a strong shortwave
station. Check to see if there are small ceramic caps' across each
diode.
There's also a possibility that the power supply wires are picking up
some interference being radiated by the digital display circuitry of the
R8B. Try installing a .01-mfd ceramic cap' rated at least 25-V, across
the DC power terminals. You could do the same with a cap' from each
terminal to the chassis ground. Hope this helps.
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