Being driven to a frenzy to own a "Regulated" power supply for my DX-398, I
bought the Radio Shack 273-1667 Multi-Voltage Wall Wart. It is regulated, has
an 800 ma output, and as the Multi-Voltage reference suggests, it is capable
of 3, 4.5, 6, 7.5, 9, and 12 Volts.
I bought this to replace the 273-1758 Unregulated supply at 6VDC and 300 ma.
I thought the Regulated supply would be better for the radio, since the
voltage would be held constant. When I travel, I always take the DX-398, and
this year was no exception. While using it, I noticed that when the display
light (LED) was on, it produced an unusually harsh static sound through the
speaker, usually evident only on certain frequencies, and not always limited
to the signal being weak on those frequencies. Easy enough fix, I left the
display light off.
Strange I thought, evidently a design problem with the DX-398. Eventually,
while still on vacation, I noticed that when the radio was running from the
batteries, with (of course) the AC adapter unplugged from the radio, the same
frequencies were clear of the harsh static when the display light was on or
off. As there was a transformer within 30 feet of the window of the cabin, I
attributed it to some kind of interference from that, and forgot the entire
Since we have been home a couple of weeks now, I noticed that the harsh static
was evident even here in the same way as described above. Remove the AC
adapter from the radio, and viola, the static ceased. I thought that this was
odd, as I have had the radio for a couple of year now, and only recently
noticed this problem. What of the old adapter I thought, that worthless
Unregulated supply that I bought with the radio. I substituted the Unregulated
supply for the Regulated supply. No more static, regardless of the display
being on or off.
Needless to say, I now use the Unregulated supply. Don't get me wrong, I know
that Regulated supplies are more desirable, it's just that in this case, with
the items listed by their Radio Shack numbers above, the Multi-Voltage
Regulated supply that Radio Shack offers may be more problematic in this
situation than the Unregulated supply listed for this radio.
Does anyone know of a good source of single voltage regulated AC/DC adapters?
For those that don't understand my attempt at humor in the opening of this
post, I offer the following.
Never say never.
Nothing is absolute.