Ron Hardin wrote:

starman wrote:
to think it will, so that's why I do it. There is one down side to the
external DC supply though. When the internal supply is used, the clock
is sync'd to the AC 60-HZ frequency which makes it more accurate than
with the DC supply.

Are you sure it's sync'd? My impression was that it worked off DC in either
case.

The clock circuit uses DC for the active componants but there is a
connection through a capacitor to the AC line to a pin on the clock chip
to sync' it.

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Several people have noted that they use the same external supply from
Radio Shack that I tried, and without a noise problem. This makes me
wonder if the problem is with something *other* than the power supply
itself. Is it possible that the copper wires running from the binding
posts of the power supply to the spring clip terminals on the rear
panel of the R8B are the real problem? In other words, could they be
acting as antennas and picking up the noise I hear? If so, then the
problem would persist no matter which external power supply I used.

Steve

Have you walked your property with a portable radio looking for the
noise source?


On 22 Feb 2005 08:51:30 -0800, wrote:

Several people have noted that they use the same external supply from
Radio Shack that I tried, and without a noise problem. This makes me
wonder if the problem is with something *other* than the power supply
itself. Is it possible that the copper wires running from the binding
posts of the power supply to the spring clip terminals on the rear
panel of the R8B are the real problem? In other words, could they be
acting as antennas and picking up the noise I hear? If so, then the
problem would persist no matter which external power supply I used.

Steve

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

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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