Need quiet 6V wall wart for Icom R10 receiver/scanner
 

Switching wall warts I have tried introduce a loud "hash" that
completely hides weak signals; transformer wall warts I have tried
introduce an annoying buzz -- most likely 60 cycles.

Can anyone recommend a 400 ma wall wart with cleaner output?

Failing that, How about a simple, physically small circuit to clean up
a typical wall wart's noisy output?

Ken KC2JDY


Ken
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"Ken" wrote in message
...
Switching wall warts I have tried introduce a loud "hash" that
completely hides weak signals; transformer wall warts I have tried
introduce an annoying buzz -- most likely 60 cycles.

Can anyone recommend a 400 ma wall wart with cleaner output?

Failing that, How about a simple, physically small circuit to clean up
a typical wall wart's noisy output?

Ken KC2JDY


Ken
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These are pretty well filtered.

http://www.radioshack.com/product.as...Fid=273%2D1667

Ken,

How about just wiring up a plug to your present13.8 Volt
DC power supply, assuming you have one. Alternatively, you could fix
the wall wart, which may be one that puts out AC. If so, you could
rectify it with some diodes, filter it with about a 1000 microfarad at
16 volt electrolytic capacitor, and use a LM7812 3 pin regulator, which
would hold the output voltage to 12VDC. A LM7812 in a TO-220 case is
good for over 1 amp current draw, and so would be fine for your Icom.

This has the benefit of being cheap, easy, and being a learning
experience. Give me a shout if you need a schematic or a physical
diagram of what I am talking about. The whole thing would take 15
minutes and maybe five bucks for parts, tax included.

OOPS...didnt see the part about it needing to be a 6 volt adapter. In
that case you change from a LM7812 chip to an LM317, which is a
variable regulator. Might add 1 buck to the cost, cuz you need a
potentiometer to set the output voltage from the LM317.

You can run a 2 conductor wire off a 13.8 v. power supply and use the
'317 to lower the output to 6 volts on a line just to your Icom.

This aint rocket science, easier to do than changing a tire, and way
more interesting.

On 9 Dec 2004 10:22:56 -0800, "Psychiatrist to keyclowns"
wrote:
OOPS...didnt see the part about it needing to be a 6 volt adapter. In
that case you change from a LM7812 chip to an LM317, which is a
variable regulator. Might add 1 buck to the cost, cuz you need a
potentiometer to set the output voltage from the LM317.
You can run a 2 conductor wire off a 13.8 v. power supply and use the
'317 to lower the output to 6 volts on a line just to your Icom.

Thanks for your response.

I have plenty of big, smooth power supplies in my shack. I want to
use a wall wart for travel.

The wall warts are putting out the right DC voltage, but they are
noisy. Are there some simple, small components that will filter out
the 60-cycle buzz of the transformer warts ot the staticky hash of the
switcher warts? Ferrite toroids seem to have no effect.

I don't mind soldering something up.

Ken
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Ken,
Since you need it for travel, I would suggest build the assembly in a
small box that goes inline between the wart and the radio. Just
interrupt the cable and extend it a bit. You could build the whole
thing in a box the size of PEZ dispenser and have room left over.

An additional idea...If you measure DC coming out of the wallwart
instead of AC, it likely just needs filtering. Skip the rectifier and
go with just the capacitor and the regulator. Maybe you could start
with a higher voltage wall wart, too. The 317 regulator can handle up
to 37 volts input. If you do that the variable voltage property of the
LM317 chip would be great to use for other items requiring a wall wart,
but one of different voltage. Maybe a 14 volt or 15 volt wart would be
a start. If it puts out AC, include the rectifier diodes. If not, skip
'em.