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Linear vs Switching Power Supply

xantegh

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I know there are tons of articles on which power supply you need to pick for your ham radio equipments, but honestly the more I read the more I get confused by so many opinions. I originally bought my Switching mode power supply for my Yeasu radio based on reviews and recommendation, additionally my uniden scanners (BCT15X) comes with Switching wall wart power supply. YET some articles highlight the high frequency noise that might be produced from these PS and recommend linear instead.

I have the following TekPower Switching Mode PS 30A (Amazon.com: TekPower Analog Display TP30SWI 30 Amp DC 13.8V Switching Power Supply with Noise Offset: Home Audio & Theater) with good ham radio operators reviews.

I intend to eliminate the wall wart and connect my scanners to a DC power supply. do I have to buy a linear PS or the above should be OK to power 4 scanners, multi-coupler and a Yeasu FTM100D?
 

belvdr

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Run it and if you have no noise, then you're good. I used a JetStream 28 amp switching PS for years without issue.

The less power conversion you do from AC to DC, the less chances you have for noise ( i.e. reduce all the wall warts you can).
 

kb5udf

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Louisiana
For scanners VHF hi and above, switchers are usually fine. Modern switchers can be much better
than they used to be, but if you have a linear, save that for your shortwave/HF rig, where any little bit of noise
may matter more. For most scanner usage, I doubt you'd ever notice.
 

iMONITOR

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I know there are tons of articles on which power supply you need to pick for your ham radio equipments, but honestly the more I read the more I get confused by so many opinions. I originally bought my Switching mode power supply for my Yeasu radio based on reviews and recommendation, additionally my uniden scanners (BCT15X) comes with Switching wall wart power supply. YET some articles highlight the high frequency noise that might be produced from these PS and recommend linear instead.
Make sure your power supply has "Crowbar" protection.

Power-supply overvoltage protection, Part 1: Crowbars
 

WB9YBM

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May 6, 2019
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Niles, IL
I know there are tons of articles on which power supply you need to pick for your ham radio equipments, but honestly the more I read the more I get confused by so many opinions. I originally bought my Switching mode power supply for my Yeasu radio based on reviews and recommendation, additionally my uniden scanners (BCT15X) comes with Switching wall wart power supply. YET some articles highlight the high frequency noise that might be produced from these PS and recommend linear instead.

I have the following TekPower Switching Mode PS 30A (Amazon.com: TekPower Analog Display TP30SWI 30 Amp DC 13.8V Switching Power Supply with Noise Offset: Home Audio & Theater) with good ham radio operators reviews.

I intend to eliminate the wall wart and connect my scanners to a DC power supply. do I have to buy a linear PS or the above should be OK to power 4 scanners, multi-coupler and a Yeasu FTM100D?
I've used both types of supplies so I can say from experience (and without boring everyone with excessive details) that I can vouch that I've had better results with linear supplies. Specifically I have several manufactured by Astron (all different ratings) and have had the best luck with those.
 

AC9BX

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Lockport, IL
Switch mode power supplies and related devices are everywhere, furnace blower controllers, washing machines, coffee makers, cell phone chargers, TV sets, and on and on. Designed well with thorough filtering a switch mode power supply is applicable to any device. However, without thorough filtering they make a great deal of RF hash. Although it's possible with a linear supply they almost never make any RF noise.
Example, Yaesu makes(made) a switch mode supply that fits inside their FT897D HF/SW radio. Without sufficient filtering this would be a disaster. If you examine the schematic you'll find it's very thoroughly filtered. In other cases you can look at the board for a supply and see missing components. The joke is, which may indeed be completely true, in development they keep removing components until it fails. Then they put that one back in and start manufacturing with minimum components to save money. The noise issues are getting worse.
A switch mode supply with sharp square waves inside (common) will make RF noise well into VHF and even up in to UHF.
Switch mode supplies are generally much more efficient, much smaller, much lighter, cooler, much cheaper. Linear supplies are the opposite.
Switch mode supplies are far more susceptible to damage from surges and spikes and brown-outs unless well designed against such things. Linear supplies are the opposite.
Switch mode supplies are more prone to malfunction in extreme heat and cold. Linear supplies don't much care.
Additional complexity of a well designed switch mode supply begins to negate the benefits of size & cost. All the same could be said about class D audio amplifiers versus linear.
 
Last edited:

Chronic

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A linear supply will produce more heat in the room , if that is a issue for you . The are not noisy on the radio equipment , but sometimes they are noise to the ear. A slight buzzing sound from the transformer .
 

iMONITOR

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A linear supply will produce more heat in the room , if that is a issue for you . The are not noisy on the radio equipment , but sometimes they are noise to the ear. A slight buzzing sound from the transformer .
My Astron doesn't buzz and the heat sink on the back is no warmer than my cat. :) But it is not loaded anywhere near 12A, more like 2A. I'm powering four Uniden scanners and a 4-port active multicoupler.
 

Scan125

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Apr 30, 2014
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Just some ramblings from a retired electrical and electronics engineer :)

I've designed both linear, SMPS and hybrid PSU and Capacitor Charging Units covering that ranges from typical low voltage/high voltage, low current/high current units. Top end would be 10kV @ 60kW / 300kV @ 1kW.

Every application (especially in the custom cases I'm talking off) requires a fundamental understanding of the "spectrum" of not just what you may be trying to cover in terms of voltage(s) and current(s) but also what design/methodology with be too dirty/noisy, too heat producing, too large, too heavy/bulky etc.

What is also crucial/critical is the target unit's immunity to electrical noise, voltage tolerance, "brown outs" (American term for temporary power input loss) etc.

It is very common now for modern equipment to require multiple voltage supplies internally. In many cases (example) your 12V input will be used to generate +5V, -5V, +12V, +/- other (eg for displays). So whilst we think about linear vs smps for the prime power input the kit will probably be using smps circuits internally. In these cases the manufacturer will have ensured any noise etc. is not an issue for the transceiver/receiver.

Decently designed SMPS can be made to be very clean and lean and compact. One side effect of compact is most will add a fan. Fans are noisy and get noisier over time.

My general view is that you have to compromise on space, efficiency, cost, etc. etc. Even linear PSU are noisy from 50Hz/100Hz and yes the diodes that do rectification can produce soft harmonics above 50/100 Hz.

For those looking for a pure DC solution then you need to power off a decent lead acid/lithium battery (with no charger enabled) and when you go to bed / switch off then turn the charger on to recharge your "PURE" DC power source.
 

mmckenna

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Decently designed SMPS can be made to be very clean and lean and compact. One side effect of compact is most will add a fan. Fans are noisy and get noisier over time.
I maintain about 30 -48vdc power systems and inverter plants for a large distributed PBX system, as well as running the network core routers.

We moved from linear power supplies to switch mode systems back in the late 1990's. Some of these systems are running several hundred amps at 48 volts from hot swappable rectifier modules. The PBX system is really susceptible to noise, especially in the voice frequency ranges.
We haven't had any issues since moving to these systems.

As for reliability, I've got a few systems that have been running 24x7 since 2008, others are newer. No failures big enough to knock our system down, occasionally an individual module will go, but those are easy to swap out.

As a bonus, our energy consumption went down, and instead of having a full rack full of ferro-resonate systems for -just- 48volts, we have a 7 rack unit system that will give us about 400 amps as well as distribution, and a 20 rack unit system that will give us 12KVA at 208 volts for the network gear. Not to mention a lot less heat generated.
 

nanZor

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Some supplies (both switching and analog) don't have input filtering, where noise from supply itself gets pumped back into your AC wiring, which makes a great full-house noise antenna.

So despite the output cabling being filtered or choked off, one can benefit from something Like a Tripp-Lite Isobar which has low-frequency filtering (hf and am band stuff), along with higher vhf band filtering.

I found that the IsoBar rf-filtering actually works.
 

krokus

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What is also crucial/critical is the target unit's immunity to electrical noise, voltage tolerance, "brown outs" (American term for temporary power input loss) etc.
Brown outs are a reduction in voltage, or loss of a phase. (Termed from the brown color that incandescent light bulbs would emit.)
 

Scan125

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Some supplies (both switching and analog) don't have input filtering, where noise from supply itself gets pumped back into your AC wiring, which makes a great full-house noise antenna.

So despite the output cabling being filtered or choked off, one can benefit from something Like a Tripp-Lite Isobar which has low-frequency filtering (hf and am band stuff), along with higher vhf band filtering.

I found that the IsoBar rf-filtering actually works.
All of today's EMC testing country standards agencies test both conducted and radiated RFI noise. To this end it is highly unlikely tested commercial product will pass without SOME form of input, output and radiated filtering/shielding. However these standards are designed to protect the public and local power lines and radio reception from excessive/disruptive interference.

Clearly many radio enthusiasts operate in the "very small signal" regions and any RFI (especially in band) is a real problem and for many additional "in house" filtering is required.

The bigger problem is that whilst you can try to minimise what comes in to you on the power lines and what you pump back out the RFI from next doors plasma TV, street lights, etc. (all perfectly legal) are beyond your control without investment in directional antennas, active noise cancelling devices/methods.
 

prcguy

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So Cal - Richardson, TX - Tewksbury, MA
For conducted RFI in or out of your house on the power lines, you can snuff out a good amount of it by placing a bunch of these ferrites over the 110/220 lines into your house. They snap on and have a 1" ID which fits fine over the wiring to my 200A service. I placed a bunch right where the power company wiring enters a weather head and vertical conduit to my breaker box. 10 of these "beads" in series will give about 1250 ohms of choking resistance at 10MHz and upwards of 3,750 ohms at 100MHz.

This particular vendor is the cheapest I've found, others want $19 to $21 just for one core. Fair-Rite 1.01″ ID Ferrite Snap-It Core - Pro Audio Engineering

All of today's EMC testing country standards agencies test both conducted and radiated RFI noise. To this end it is highly unlikely tested commercial product will pass without SOME form of input, output and radiated filtering/shielding. However these standards are designed to protect the public and local power lines and radio reception from excessive/disruptive interference.

Clearly many radio enthusiasts operate in the "very small signal" regions and any RFI (especially in band) is a real problem and for many additional "in house" filtering is required.

The bigger problem is that whilst you can try to minimise what comes in to you on the power lines and what you pump back out the RFI from next doors plasma TV, street lights, etc. (all perfectly legal) are beyond your control without investment in directional antennas, active noise cancelling devices/methods.
 

iMONITOR

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For conducted RFI in or out of your house on the power lines, you can snuff out a good amount of it by placing a bunch of these ferrites over the 110/220 lines into your house. They snap on and have a 1" ID which fits fine over the wiring to my 200A service. I placed a bunch right where the power company wiring enters a weather head and vertical conduit to my breaker box. 10 of these "beads" in series will give about 1250 ohms of choking resistance at 10MHz and upwards of 3,750 ohms at 100MHz.

This particular vendor is the cheapest I've found, others want $19 to $21 just for one core. Fair-Rite 1.01″ ID Ferrite Snap-It Core - Pro Audio Engineering
Hum...I'd have to dig a deep hole, mine is underground. I have a 200 AMP panel, I wonder if there is enough room inside?
 

a417

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Mar 14, 2004
Messages
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Hum...I'd have to dig a deep hole, mine is underground. I have a 200 AMP panel, I wonder if there is enough room inside?
is there enough room directly before the conduit enters the panel? If it comes in from the top or bottom you might be ok, if it's back-fed....good luck?
 
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