On Feb 6, 8:25 pm, Ian White GM3SEK wrote:
Andrew VK3BFA wrote:

Never said there were no quiet switchers - just that the majority were
not....Google on SMPS noise to prove.....

Sure... but SMPS noise is categorically NOT about "the luck of the draw"
(as you claimed a few days ago).

It's all about skill and care in the design - above all, the input and
output filtering. Done correctly, there are no problems, as proved by
the many base-station HF transceivers that have a mains SMPS built in.

When you buy a separate SMPS, don't trust to luck. Be an intelligent
consumer: read the reviews, specify what you need, ask what has been
done to minimize the noise levels, and be prepared to return the unit or
walk away.

The only real "luck" is about the SMPSes in other things that your
family and neighbours may buy...

--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)http://www.ifwtech.co.uk/g3sek

MM, well.....ok., I will add a rider to the "luck of the draw" - if
you have the knowledge of the things in the first place, it is
axiomatic that you would need to check it out before you buy it - get
test data, spectrum analyser screen shots, copy of CE certification'
load test data, a copy of the service manual for future
reference...probably a few more things as well, I forget.

The rest of us, well.........we basically know bugger all about them,
and we havent been hams long enough for someone to tell us "Brand X"
is useless. SO we go and buy it, and wonder what the hell went wrong.

And I been fixing the things for 20 years now as a lowly service tech
- horrible things, havent seen a quiet one yet..

AND AND...its going to get worse. Plasma TV's radiate to buggery -
they have big, and good, filters on the SMPS power supply, but they
are S9 at 5 miles.......LCD is better - EXCEPT for the plug pack SMPS
type 12v etc power supply hanging off them...had one in for repair,
the only sign it was polluting was that the (non ham) owner complained
it was interfering with his AM radio reception. (That was interesting
in its own right - he had contacted the relevant authority, they had
sent him a "do it yourself" booklet, and he found it...I thought that
was a pretty good effort)

And the "Brand X" (still on sale, still selling in the shops) - one
hapless inexperienced amateur asked me to "modify" - ie quieten it
down. Plastic from and rear panels. Bugger all input filtering - and
virtually none anywhere else. On 160m, spot frequencies, it was S9+. I
got it down to S3, then gave up in disgust.

So, Ian - love your columns, in awe of your knowledge about practical,
real radio. I certainly havent got all that much. But this is the
view from the trenches, as it were - everyday practical pointy end
servicing - so,if I may, I humbly beg to differ. No offense meant, to
anyone, and none taken. (Yep - its true - I don't like them...)

Andrew VK3BFA