On Feb 4, 3:55 am, Andrew VK3BFA wrote:
On Feb 4, 10:13 pm, Leon wrote:

On 28 Jan, 11:27, "Richard" wrote:

I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU feeding
24V @ about 300mA.

Are switch-mode powers supplies alright or are they too noisy to be used for
receivers? TIA.

I use a 12V switcher with my FT-817D, it's very quiet.

Leon

You were lucky - you got a quiet one. And its the luck of the draw,
unfortunately.

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle. And if it works on 2m and above, fine - you
will just be adding to the already horrendous RF pollution from
thousands of the bloody things already on HF - the suburbs are getting
unbearable, S9 plus noise, every night, on 80m.....160 aint to crash
hot either...

I refuse to have to work on a power supply to get it quiet enough to
be used with a radio. I am interested in the radio, not fixing
shortcomings in design of things that , by their very nature, are
unsuitable to be used near radios. That sucks. Linear technology is
far easier and quieter...

Andrew VK3BFA.

There's another advantage of a switching supply that is very important
to some of us: efficiency. The receiver I've been working on runs
from 5VDC, but I have to supply power at 1.0V, 1.2V 1.8V, 2.5V and
3.3V, and each one of those uses a switcher. A linear regulator to 1V
from 5V will result in a supply that's 20% efficient. The switcher
I'm using for that supply is about 87% efficient under its operating
conditions. If I tried to run all my supplies with linear regulators,
I'd have to supply over twice the power; it would come close to
violating the power rating of the 5V supply, and power dissipation in
the receiver would result in excessive heat rise.

But even with all those switchers, the only spurs greater than about
-145dBm (antenna-input-referred) and greater than 1.5MHz are from
digital circuits, not the power supplies. -145dBm is, I believe, 20dB
_below_ S1 by usual definition of the S-meter units. Even the power
supply fundamentals are only at about S1. And the supplies are not
themselves shielded. (The receiver RF circuitry is, of course, as is
the whole receiver module.)

I would be much more circumspect about using a switching supply in a
homebrew receiver that was going to be used where power dissipation
wasn't an issue, but then I'd do a lot of things differently than I
have for such a receiver. It wouldn't keep me from using switchers;
I'd just look at the whole design in a different way. On the other
hand, finding ones that would be adequately quiet for a 144MHz
receiver should not be difficult at all.

Cheers,
Tom

On Feb 5, 3:52 am, K7ITM wrote:
On Feb 4, 3:55 am, Andrew VK3BFA wrote:



On Feb 4, 10:13 pm, Leon wrote:

On 28 Jan, 11:27, "Richard" wrote:

I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU feeding
24V @ about 300mA.

Are switch-mode powers supplies alright or are they too noisy to be used for
receivers? TIA.

I use a 12V switcher with my FT-817D, it's very quiet.

Leon

You were lucky - you got a quiet one. And its the luck of the draw,
unfortunately.

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle. And if it works on 2m and above, fine - you
will just be adding to the already horrendous RF pollution from
thousands of the bloody things already on HF - the suburbs are getting
unbearable, S9 plus noise, every night, on 80m.....160 aint to crash
hot either...

I refuse to have to work on a power supply to get it quiet enough to
be used with a radio. I am interested in the radio, not fixing
shortcomings in design of things that , by their very nature, are
unsuitable to be used near radios. That sucks. Linear technology is
far easier and quieter...

Andrew VK3BFA.

There's another advantage of a switching supply that is very important
to some of us: efficiency. The receiver I've been working on runs
from 5VDC, but I have to supply power at 1.0V, 1.2V 1.8V, 2.5V and
3.3V, and each one of those uses a switcher. A linear regulator to 1V
from 5V will result in a supply that's 20% efficient. The switcher
I'm using for that supply is about 87% efficient under its operating
conditions. If I tried to run all my supplies with linear regulators,
I'd have to supply over twice the power; it would come close to
violating the power rating of the 5V supply, and power dissipation in
the receiver would result in excessive heat rise.

But even with all those switchers, the only spurs greater than about
-145dBm (antenna-input-referred) and greater than 1.5MHz are from
digital circuits, not the power supplies. -145dBm is, I believe, 20dB
_below_ S1 by usual definition of the S-meter units. Even the power
supply fundamentals are only at about S1. And the supplies are not
themselves shielded. (The receiver RF circuitry is, of course, as is
the whole receiver module.)

I would be much more circumspect about using a switching supply in a
homebrew receiver that was going to be used where power dissipation
wasn't an issue, but then I'd do a lot of things differently than I
have for such a receiver. It wouldn't keep me from using switchers;
I'd just look at the whole design in a different way. On the other
hand, finding ones that would be adequately quiet for a 144MHz
receiver should not be difficult at all.

Cheers,
Tom

Hi Tom,
all points noted, and readily conceded - if the things didn't have
SOME advantages besides low cost, well....
You've got yours down to S1 - mm, well,......so thats the noise floor
you are limited to. And thats probably on a small range of
frequencies, gawd knows where else it is radiating...(and adding to
phase noise in your receiver...)

And, lets be honest, if it isn't causing ME QRM, on the frequency I
want to operate, then its OK......fine for VHF/UHF unless a spur is on
your IF frequency...

The only application I can see for them is, as you say, where low
power consumption/efficiency is paramount - but if you can plug your
switch mode power supply into a source of AC power, then whats the
problem with lugging a quiet linear supply as well as the generator
required to run it?

To me, they are a flawed technology, and in a better place would not
be allowed to be used because of their inherent design flaws...

Andrew VK3BFA.

(PS - I do a good "back in the good old days" rant if you like.....)

Andrew VK3BFA wrote:
On Feb 5, 3:52 am, K7ITM wrote:
On Feb 4, 3:55 am, Andrew VK3BFA wrote:



On Feb 4, 10:13 pm, Leon wrote:

On 28 Jan, 11:27, "Richard" wrote:

I have an ex AM PMR radio that I wish to use on 144Mhz. I need a
PSU feeding
24V @ about 300mA.

Are switch-mode powers supplies alright or are they too noisy to
be used for
receivers? TIA.

I use a 12V switcher with my FT-817D, it's very quiet.

Leon

You were lucky - you got a quiet one. And its the luck of the draw,
unfortunately.

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle. And if it works on 2m and above, fine - you
will just be adding to the already horrendous RF pollution from
thousands of the bloody things already on HF - the suburbs are getting
unbearable, S9 plus noise, every night, on 80m.....160 aint to crash
hot either...

I refuse to have to work on a power supply to get it quiet enough to
be used with a radio. I am interested in the radio, not fixing
shortcomings in design of things that , by their very nature, are
unsuitable to be used near radios. That sucks. Linear technology is
far easier and quieter...

Andrew VK3BFA.

There's another advantage of a switching supply that is very important
to some of us: efficiency. The receiver I've been working on runs
from 5VDC, but I have to supply power at 1.0V, 1.2V 1.8V, 2.5V and
3.3V, and each one of those uses a switcher. A linear regulator to 1V
from 5V will result in a supply that's 20% efficient. The switcher
I'm using for that supply is about 87% efficient under its operating
conditions. If I tried to run all my supplies with linear regulators,
I'd have to supply over twice the power; it would come close to
violating the power rating of the 5V supply, and power dissipation in
the receiver would result in excessive heat rise.

But even with all those switchers, the only spurs greater than about
-145dBm (antenna-input-referred) and greater than 1.5MHz are from
digital circuits, not the power supplies. -145dBm is, I believe, 20dB
_below_ S1 by usual definition of the S-meter units. Even the power
supply fundamentals are only at about S1. And the supplies are not
themselves shielded. (The receiver RF circuitry is, of course, as is
the whole receiver module.)

I would be much more circumspect about using a switching supply in a
homebrew receiver that was going to be used where power dissipation
wasn't an issue, but then I'd do a lot of things differently than I
have for such a receiver. It wouldn't keep me from using switchers;
I'd just look at the whole design in a different way. On the other
hand, finding ones that would be adequately quiet for a 144MHz
receiver should not be difficult at all.

Cheers,
Tom

Hi Tom,
all points noted, and readily conceded - if the things didn't have
SOME advantages besides low cost, well....
You've got yours down to S1 - mm, well,......so thats the noise floor
you are limited to. And thats probably on a small range of
frequencies, gawd knows where else it is radiating...(and adding to
phase noise in your receiver...)

And, lets be honest, if it isn't causing ME QRM, on the frequency I
want to operate, then its OK......fine for VHF/UHF unless a spur is on
your IF frequency...

The only application I can see for them is, as you say, where low
power consumption/efficiency is paramount - but if you can plug your
switch mode power supply into a source of AC power, then whats the
problem with lugging a quiet linear supply as well as the generator
required to run it?

To me, they are a flawed technology, and in a better place would not
be allowed to be used because of their inherent design flaws...

Andrew VK3BFA.

(PS - I do a good "back in the good old days" rant if you like.....)

We use a couple of homebrew regulated DC-DC boost converters during Field
Day, one to run the HF xcvr (13.8VDC @ 25A peak) and one to run the laptop
PC for logging (16VDC @ 4.5A), from a 12V wet cell battery "pack"*. Prior
to use, they were "sniffed" (at no load and also full load) with an HP
spectrum analyzer. The analyzer showed only a few very weak spurs in the HF
spectrum that we couldn't hear at all, even on 80m. Of course, they were
properly designed with this use in mind... good decoupling and shielding.
Switching rate is 500KHz; efficiency is in the neighborhood of 90%.

* Battery "pack":
http://img22.imagevenue.com/img.php?...122_1054lo.jpg

Bryan WA7PRC

On Feb 5, 4:46 pm, Andrew VK3BFA wrote:
On Feb 5, 3:52 am, K7ITM wrote:



On Feb 4, 3:55 am, Andrew VK3BFA wrote:

On Feb 4, 10:13 pm, Leon wrote:

On 28 Jan, 11:27, "Richard" wrote:

I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU feeding
24V @ about 300mA.

Are switch-mode powers supplies alright or are they too noisy to be used for
receivers? TIA.

I use a 12V switcher with my FT-817D, it's very quiet.

Leon

You were lucky - you got a quiet one. And its the luck of the draw,
unfortunately.

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle. And if it works on 2m and above, fine - you
will just be adding to the already horrendous RF pollution from
thousands of the bloody things already on HF - the suburbs are getting
unbearable, S9 plus noise, every night, on 80m.....160 aint to crash
hot either...

I refuse to have to work on a power supply to get it quiet enough to
be used with a radio. I am interested in the radio, not fixing
shortcomings in design of things that , by their very nature, are
unsuitable to be used near radios. That sucks. Linear technology is
far easier and quieter...

Andrew VK3BFA.

There's another advantage of a switching supply that is very important
to some of us: efficiency. The receiver I've been working on runs
from 5VDC, but I have to supply power at 1.0V, 1.2V 1.8V, 2.5V and
3.3V, and each one of those uses a switcher. A linear regulator to 1V
from 5V will result in a supply that's 20% efficient. The switcher
I'm using for that supply is about 87% efficient under its operating
conditions. If I tried to run all my supplies with linear regulators,
I'd have to supply over twice the power; it would come close to
violating the power rating of the 5V supply, and power dissipation in
the receiver would result in excessive heat rise.

But even with all those switchers, the only spurs greater than about
-145dBm (antenna-input-referred) and greater than 1.5MHz are from
digital circuits, not the power supplies. -145dBm is, I believe, 20dB
_below_ S1 by usual definition of the S-meter units. Even the power
supply fundamentals are only at about S1. And the supplies are not
themselves shielded. (The receiver RF circuitry is, of course, as is
the whole receiver module.)

I would be much more circumspect about using a switching supply in a
homebrew receiver that was going to be used where power dissipation
wasn't an issue, but then I'd do a lot of things differently than I
have for such a receiver. It wouldn't keep me from using switchers;
I'd just look at the whole design in a different way. On the other
hand, finding ones that would be adequately quiet for a 144MHz
receiver should not be difficult at all.

Cheers,
Tom

Hi Tom,
all points noted, and readily conceded - if the things didn't have
SOME advantages besides low cost, well....
You've got yours down to S1 - mm, well,......so thats the noise floor
you are limited to. And thats probably on a small range of
frequencies, gawd knows where else it is radiating...(and adding to
phase noise in your receiver...)

And, lets be honest, if it isn't causing ME QRM, on the frequency I
want to operate, then its OK......fine for VHF/UHF unless a spur is on
your IF frequency...

The only application I can see for them is, as you say, where low
power consumption/efficiency is paramount - but if you can plug your
switch mode power supply into a source of AC power, then whats the
problem with lugging a quiet linear supply as well as the generator
required to run it?

To me, they are a flawed technology, and in a better place would not
be allowed to be used because of their inherent design flaws...

Andrew VK3BFA.

(PS - I do a good "back in the good old days" rant if you like.....)

Oh, well, the receiver is 100kHz (nom.; actually is -3dB at about
18kHz) to about 38MHz. It also alternately does 70MHz IF at 36MHz
bandwidth, at about the same sensitivity. Noise figure on HF is
around 9dB at max sensitivity; since switchers are not stable sources,
their output becomes broadband noise by the time you get to bandwidths
low enough to see -145dBm (e.g., 100Hz), and there's essentially no
indication of increased noise floor at the harmonics (past maybe the
third) of any of the supplies, even with lots of averaging. The
master clock is a low phase noise VCTCXO, and it IS run from a linear
supply, with scrubbing added. That oscillator really does set the
system phase noise. There are no other oscillators to worry about in
the signal chain.

You're welcome to rant about the "good old days," but I probably won't
hear it. I'm too busy enjoying the "even better new days" to bother
looking back.

Cheers,
Tom

On Feb 6, 5:50 pm, K7ITM wrote:
On Feb 5, 4:46 pm, Andrew VK3BFA wrote:



On Feb 5, 3:52 am, K7ITM wrote:

On Feb 4, 3:55 am, Andrew VK3BFA wrote:

On Feb 4, 10:13 pm, Leon wrote:

On 28 Jan, 11:27, "Richard" wrote:

I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU feeding
24V @ about 300mA.

Are switch-mode powers supplies alright or are they too noisy to be used for
receivers? TIA.

I use a 12V switcher with my FT-817D, it's very quiet.

Leon

You were lucky - you got a quiet one. And its the luck of the draw,
unfortunately.

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle. And if it works on 2m and above, fine - you
will just be adding to the already horrendous RF pollution from
thousands of the bloody things already on HF - the suburbs are getting
unbearable, S9 plus noise, every night, on 80m.....160 aint to crash
hot either...

I refuse to have to work on a power supply to get it quiet enough to
be used with a radio. I am interested in the radio, not fixing
shortcomings in design of things that , by their very nature, are
unsuitable to be used near radios. That sucks. Linear technology is
far easier and quieter...

Andrew VK3BFA.

There's another advantage of a switching supply that is very important
to some of us: efficiency. The receiver I've been working on runs
from 5VDC, but I have to supply power at 1.0V, 1.2V 1.8V, 2.5V and
3.3V, and each one of those uses a switcher. A linear regulator to 1V
from 5V will result in a supply that's 20% efficient. The switcher
I'm using for that supply is about 87% efficient under its operating
conditions. If I tried to run all my supplies with linear regulators,
I'd have to supply over twice the power; it would come close to
violating the power rating of the 5V supply, and power dissipation in
the receiver would result in excessive heat rise.

But even with all those switchers, the only spurs greater than about
-145dBm (antenna-input-referred) and greater than 1.5MHz are from
digital circuits, not the power supplies. -145dBm is, I believe, 20dB
_below_ S1 by usual definition of the S-meter units. Even the power
supply fundamentals are only at about S1. And the supplies are not
themselves shielded. (The receiver RF circuitry is, of course, as is
the whole receiver module.)

I would be much more circumspect about using a switching supply in a
homebrew receiver that was going to be used where power dissipation
wasn't an issue, but then I'd do a lot of things differently than I
have for such a receiver. It wouldn't keep me from using switchers;
I'd just look at the whole design in a different way. On the other
hand, finding ones that would be adequately quiet for a 144MHz
receiver should not be difficult at all.

Cheers,
Tom

Hi Tom,
all points noted, and readily conceded - if the things didn't have
SOME advantages besides low cost, well....
You've got yours down to S1 - mm, well,......so thats the noise floor
you are limited to. And thats probably on a small range of
frequencies, gawd knows where else it is radiating...(and adding to
phase noise in your receiver...)

And, lets be honest, if it isn't causing ME QRM, on the frequency I
want to operate, then its OK......fine for VHF/UHF unless a spur is on
your IF frequency...

The only application I can see for them is, as you say, where low
power consumption/efficiency is paramount - but if you can plug your
switch mode power supply into a source of AC power, then whats the
problem with lugging a quiet linear supply as well as the generator
required to run it?

To me, they are a flawed technology, and in a better place would not
be allowed to be used because of their inherent design flaws...

Andrew VK3BFA.

(PS - I do a good "back in the good old days" rant if you like.....)

Oh, well, the receiver is 100kHz (nom.; actually is -3dB at about
18kHz) to about 38MHz. It also alternately does 70MHz IF at 36MHz
bandwidth, at about the same sensitivity. Noise figure on HF is
around 9dB at max sensitivity; since switchers are not stable sources,
their output becomes broadband noise by the time you get to bandwidths
low enough to see -145dBm (e.g., 100Hz), and there's essentially no
indication of increased noise floor at the harmonics (past maybe the
third) of any of the supplies, even with lots of averaging. The
master clock is a low phase noise VCTCXO, and it IS run from a linear
supply, with scrubbing added. That oscillator really does set the
system phase noise. There are no other oscillators to worry about in
the signal chain.

You're welcome to rant about the "good old days," but I probably won't
hear it. I'm too busy enjoying the "even better new days" to bother
looking back.

Cheers,
Tom

Hey - I agree - I like the modern DDS chips as well, fantastic things.
(Note - AD specify separate ANALOG supply for them...Mmm?)


I try again - my point is, why bother to stuff around getting a "new"
technology to work when an "old" technology is cheap, easy,simple, and
it works with no extra fiddling.

And if you need a spectrum analyser to check your power supply for
suitability, - that is a bit ludicrous, isn't it? Mad Scientist in
attic room / Tony Hancock sketch sort of thing. Why make things so
difficult? KISS.

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

Andrew VK3BFA.

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

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

On Feb 4, 10:13 pm, Leon wrote:
On 28 Jan, 11:27, "Richard" wrote:

I have an ex AM PMR radio that I wish to use on 144Mhz. I need a PSU feeding
24V @ about 300mA.
Are switch-mode powers supplies alright or are they too noisy to be used for
receivers? TIA.
I use a 12V switcher with my FT-817D, it's very quiet.

Leon

You were lucky - you got a quiet one. And its the luck of the draw,
unfortunately.

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle. And if it works on 2m and above, fine - you
will just be adding to the already horrendous RF pollution from
thousands of the bloody things already on HF - the suburbs are getting
unbearable, S9 plus noise, every night, on 80m.....160 aint to crash
hot either...

I refuse to have to work on a power supply to get it quiet enough to
be used with a radio. I am interested in the radio, not fixing
shortcomings in design of things that , by their very nature, are
unsuitable to be used near radios. That sucks. Linear technology is
far easier and quieter...
========================================
When using a switcher (in a metal sealed enclosure and with noise
supressors ,as recommended by some in this thread), put a sealed lead
acid battery in parallel.
If still noisy you then can switch-off switcher when rx-ing .

Frank GM0CSZ / KN6WH

How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle.

Other advantages include much better power efficiency and much lower weight.

It's not particularly difficult to make a switcher with very good (meaning
very little) noise output, but relatively few applications call for it, and
given how incredibly competitive the power supply arena is, it's not
surprising that a lot of companies drop a few components to reduce their costs
at the expense of noise.

On Feb 21, 4:58 am, "Joel Koltner"
wrote:
How come we have all been conned into these switchmode things? - by
their very nature, without a lot of effort, they are noise generators.
Their cheap to make, thats their only advantage - everything else is
part of the spin cycle.

Other advantages include much better power efficiency and much lower weight.

It's not particularly difficult to make a switcher with very good (meaning
very little) noise output, but relatively few applications call for it, and
given how incredibly competitive the power supply arena is, it's not
surprising that a lot of companies drop a few components to reduce their costs
at the expense of noise.

re power and weight - I was having a rant, so deliberately left out
the inconvenient facts.....(Yes, I thats unusual, isnt it - I must
reprimand myself)

And yes, will readily concede the " they can be well designed bit"...

But they are not. The percentage? - dont know. All I can do is hear
them, on air. Went away at Xmas, remote caravan park, MILES away,
looking forward to HF radio . Nope, surrounded by modern caravans with
12v systems, run from noisy SMPS power supplies/battery chargers....it
was better, 80m QRM was S3 instead of S9+

Gosh, modern electronics IS wonderful, isnt it....

My point stands.

Andrew VK3BFA.