Power Supplies, RF quiet, Linear or Switching?

iMONITOR

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I'm in need of a new 13.8VDC power supply. I'm old school and have always been told linear is better than switching due to RF noise generated by switching power supplies. However I'm hearing lately that's no longer true and that some switching supplies are just as quiet as linear. I like that they are much smaller and are not as heavy. I'm needing something to power 3 Uniden desktop scanners, approx. 750mA each, and an ICOM IC-R8600 receiver requiring 2A. I used to have a 12A Astron but it was fairly large and heavy.

What do you pros recommend?

Thanks!
 

mmckenna

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I run a number of repeater sites, and -all- the power systems are switching power supplies. I've got a bunch of small base stations scattered around work, all switching power supplies. My own stuff at home, all switching power supplies.

I have a few Duracomm and they seem to work just fine.
Most of the stuff at work is Samlex.
 

iMONITOR

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I run a number of repeater sites, and -all- the power systems are switching power supplies. I've got a bunch of small base stations scattered around work, all switching power supplies. My own stuff at home, all switching power supplies.

I have a few Duracomm and they seem to work just fine.
Most of the stuff at work is Samlex.
Thanks for responding I value your input and expertise. Do they all have fans and if so are they noisy?
 

MDScanFan

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I have never noticed an issue with switching supplies causing an issue for >30 MHz reception. However, I have noticed an impact <30 MHz where RF hash would show up at different frequency bands - it would vary from one supply to another. Since I do a mix of listening I ended up using linear suppliers for everything to keep things simple. This decision was made ~10 years ago and I have not tried any larger amperage switching supplies since then. I am sure there are decent switching supplies out there that would not impact HF.

For receive only I would think a ~7 amp supplier should be sufficient for several radios.
 

mmckenna

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Pretty sure they hall have fans, and no, not noisy.

I have a Astron at home. It was originally running some radios at work in our old dispatch center. When the dispatch center moved to a new building, I retired it. Other than a few brief power outages and the move to my house, it's been running 24x7 since 2003.
It ran a number of VHF radios used for monitoring adjacent agencies, and was housed in racks that contained dispatch consoles, 800MHz and VHF transceivers.
Won't be a problem with your scanners.
 

WB9YBM

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I'm in need of a new 13.8VDC power supply. I'm old school and have always been told linear is better than switching due to RF noise generated by switching power supplies. However I'm hearing lately that's no longer true and that some switching supplies are just as quiet as linear. I like that they are much smaller and are not as heavy.
True: they were rather noisy way back when, but they have improved since their inception. Smaller is also nice if you've got limited space on your operating set-up. As for their lighter weight, that probably only matters if you're planning to do portable operation of some type or another.

That being said, my supplies have always been linear and when I'm not using a home-made supply I buy Astron exclusively. It's the brand I've had the best luck with over the longest period of time; to quote an old proverb, "if it ain't broke don't fix it."
 

jwt873

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I've been running an Alinco 35 Amp switching supply for 16 years. I use it for my HF and VHF/UHF radios. I've never had a problem with RF hash. But as mentioned, modern supplies have pretty well done away with that. (Even Astron has a switching supply line now).

Out of interest my Alinco supply has a potentiometer I can twist to adjust the internal oscillator frequency just in case an interfering birdie should appear in the receiver. Changing the frequency will cause the birdie to shift up or down in frequency. I've never had to use it.

But I I were looking for a supply for what you require, I'd just go with something like a linear Astron RS-7A or Perhaps an RS-11A. They aren't all that bulky compared to something like the RS-35A
 

prcguy

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Astron is the leader in amateur use power supplies. They sell more than anyone and they have the best in and out of warranty policy there is. I've had several Astron switchers including SS-18, SS-25 and SS-30 series, some running for nearly 30yrs continuous without a hint of trouble. I've blown up a couple of older Astron linear supplies, completely my fault and Astron fixed them for $20 flat rate including adding all current upgrades and replacing meters. I've never had any interference from an Astron switcher and from day one my Icom R8600 has been powered by an Astron SS-30 along with several other radios.
 

AK9R

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I've never had any interference from an Astron switcher and from day one my Icom R8600 has been powered by an Astron SS-30 along with several other radios.
Does that include using the R8600 to monitor HF frequencies?
 

ridgescan

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HRO sold me an Astron RS-4A to go with my R8600. I assume they know what they're doing and it's quiet across the bands far as I can see. I run a Samlex RSP-1207 on the R75 in the living room and it's nice and quiet too.
 

belvdr

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I've had a Jetstream JTPS28 for 14 years and have had no interference from it.
 

N4KVE

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Sometimes the Astron SS30 fan will kick on even though I’m not transmitting. It is sort of noisy, so I put a 100 ohm resistor in the wire to the fan to slow it down. Now I don’t hear it at all, & the PS remains cool, even when I am transmitting.
 

wa8pyr

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I'm in need of a new 13.8VDC power supply. I'm old school and have always been told linear is better than switching due to RF noise generated by switching power supplies. However I'm hearing lately that's no longer true and that some switching supplies are just as quiet as linear. I like that they are much smaller and are not as heavy. I'm needing something to power 3 Uniden desktop scanners, approx. 750mA each, and an ICOM IC-R8600 receiver requiring 2A. I used to have a 12A Astron but it was fairly large and heavy.

What do you pros recommend?
I use a MegaWatt switching supply on my IC7300, R8600 and a couple of Motorola radios at home, works like a charm, and plenty of capacity. Beware of the supplies that look the same but aren't genuine MegaWatt; they're cheap Chinese knockoffs with a filthy dirty output (the MegaWatt is nice and clean).

 

prcguy

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Another power supply I might recommend is the Powerwerx 30A desktop, I have one on an unattended remote control station and one for travel. I've only had them for about two years but they don't seem to have any RFI issues and I like the Anderson Power Pole connectors on the front. These are really small for the current rating and ideal for travel. Powerwerx 30 Amp Desktop DC Power Supply with Powerpole Connectors
 

iMONITOR

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About how much current would a 30A power supply draw on 120VAC when on but idle with no load? Would a switching PS draw less than a linear in that state?
 

AK9R

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Folks, keep in mind that the OP's total current requirement at this time is 3.5 amps. He probably doesn't need a big, expensive power supply.
 

iMONITOR

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Folks, keep in mind that the OP's total current requirement at this time is 3.5 amps. He probably doesn't need a big, expensive power supply.
I've been keeping that in mind but if I size on the small side and it has a fan, I'm thinking the fan might run more often or possibly at a higher speed or run hot. I'm thinking around twice the current I actually need. I should have kept my Astron 12A. :rolleyes:
 

belvdr

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Another power supply I might recommend is the Powerwerx 30A desktop, I have one on an unattended remote control station and one for travel. I've only had them for about two years but they don't seem to have any RFI issues and I like the Anderson Power Pole connectors on the front. These are really small for the current rating and ideal for travel. Powerwerx 30 Amp Desktop DC Power Supply with Powerpole Connectors
I like that one too. They have a radio accessory box for the top:
It's odd they don't put PowerPoles on the back as well to clean things up a bit.
 
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