Hi Michael,
My test is pretty simple -- a Kenwood TH-F6A talkie tuned a bit above 2
MHz used as a probe. Testing with a receiver working into your antenna
is NOT always a good test, because there are so many other noise sources
that combine to obscure one of them alone. The average home probably
has a couple of dozen switchers by 2018 -- they come in the door with
virtually everything we buy that plugs into the wall! Some are wall
warts, some are built into the equipment itself.
Yes, there are good switchers and bad ones. All of those that have come
with my Thinkpads have been quiet. Some used switchers I found built for
use with Motorola gear are quiet. So is a 20A supply built for use by
hams. And so is the switcher in Elecraft's new KPA1500 power amp. Nearly
all that came with other stuff are not.
73, Jim K9YC
On 11/29/2018 11:36 AM, Michael Coslo wrote:
It seems to be a popular thing to condemn every switcher as noisy. Whenever I
purchase something that comes with a wall wart, I check it out with my radio on
all bands. Most pass.
What is more, if we willy nilly replace the dreaded switchers with the linear,
we could actually cause problems where one did not exist.
Being built to be cheap, the linears I have seen have a transformer, a full
wave rectifier, and a filter cap. My experience with Linear wall warts echos
this http://www.dxing.info/equipment/wall_warts_bryant.dx
If an Op wants to have no switchers, and if they want clean power. make a power
distribution system with a well regulated, properly filtered power supply, and
not allow a wall wart to be seen in their house.
But really, check out that switcher before trashing it. You aren’t gaining a
lot by going to a cheap linear wart, and might introduce problems.
- Michael Coslo -
Frequency Coordinator, Beaver Stadium
814-404-3991
mjc5@psu.edu
mjcn3li@gmail.com
On Nov 28, 2018, at 11:14 PM, Roger (K8RI) <k8ri@rogerhalstead.com> wrote:
One thing to keep in mind and this list seems to ignore. Not all switching
supplies generate noise although many, if not most do.
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