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Author Topic: PSU Advice?  (Read 2732 times)
MW1CFN
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Posts: 31




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« on: November 07, 2011, 01:34:34 AM »

Hello,

Like many people, I'm trying to put a HF station together on a budget.  I'm UK-based.

I'm thinking about PSUs, and quite why they cost so much.  Expecting I need a PSU to run about 20A maximum for a portable HF rig, I wonder if anyone has any views on what budget PSUs are worth considering?  By 'budget', I don't mean £300, nor £15 units that blow up within a few days!  If anyone has practical experience of using, shall we call them cheaper? units, then I'd be interested to hear from you.

Thanks,
K.
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VE3FMC
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« Reply #1 on: November 07, 2011, 01:18:59 PM »

I have 3 power supplies in my shack. All work well.

The oldest one is an Astron RS35M, which is currently not in use. This PS has been around for many years as it belonged to my later Father. Still works like it was new.

Next is a Jetstream JTPS30M that I bought about a year ago. Used it with two HF rigs, no problems with it. Currently powering a 2 meter mobile. It is a switching PS, rated at 30 Amps.

Last is an Alinco DM330MV switching supply which I use to power my FT-950, an LDG AT-200PRO auto tuner and the lights in my Palstar antenna tuner. No noise, works well.

If you want a small supply for portable use then the Alinco or Jetstream is the way to go. Astron also makes a small switching supply. A friend of mine uses one of those and has no issues with it.

Hope this helps you out.
Rick VE3FMC
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W8JX
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« Reply #2 on: November 07, 2011, 04:51:02 PM »

I have been using a Astron SS30 switching supply as main unit for 4 years now and never going back to the boat anchor RS35 linear unit. Light weight and far more efficient too. I have a 20 year old RS 20 as a backup that I bought new and it has run four different HF rigs in its lifetime too. Many buy bigger power supplies than they really need.
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K2OWK
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« Reply #3 on: November 07, 2011, 08:52:42 PM »

I have been using a Mega-Watt S-400-12 power supp;y for over a year now. It is capable of 30 amps continuous at 13. 6 volts. It is a switching supply and does not produce any noise or hash on the amateur bands. It is a no frills unit. It has no meters and a single pot for voltage adjust. It has a switch for 110 or 220 volt AC operation for countries that require different power options. The price is about $65.00US. If you want additional information and reviews look at the EHam review forum. It is listed under power supplies Mega-Watt.

Hope this helps,

73s

K2OWK
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NA4IT
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« Reply #4 on: November 10, 2011, 10:18:33 AM »

I use a 30 amp RV type supply charger from Cascade Audio, feeding a 150AH battery. No switching devices needed, only fuse protection. 13.6 VDC, and automatic power change when the AC dies. You can see it at www.qsl.net/na4it.
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MW1CFN
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« Reply #5 on: November 14, 2011, 12:30:02 AM »

Thanks for the useful replies!  Glad to say things progressing, so next stop - antennae  Roll Eyes

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AA4PB
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« Reply #6 on: November 14, 2011, 06:09:37 AM »

Here's the questions you need to investigate before purchasing a supply:

1) Does the input voltage range match your available AC power?

2) Is the peak output current rating of the supply at least as great as the peak current consumed by the transceiver? More is better. Don't forget to add in the current for any accessories that you may want to run from the same supply.

3) Is the supply linear or switching? Each has its advantages. Switching supplies are smaller and lighter for the same output rating but they can generate RFI (RF Interferrence to your receiver) if not well shielded and filtered. The closer your antenna is to the supply, the more of a concern this will be. Switching supplies usually contain a fan which can create acoustic noise in the shack. Linear supplies are larger and heavier but are not likely to generate any RFI. My personal preference is for a linear supply if I don't have a need to transport it.

4) Make sure that the supply has "over-voltage protection". If it doesn't and one of pass transistors shorts then a linear supply is likely to apply 24VDC or more to your transceiver - not good!
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W8JX
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« Reply #7 on: November 14, 2011, 07:46:37 AM »

Here's the questions you need to investigate before purchasing a supply:

1) Does the input voltage range match your available AC power?

Not a concern with a switching supply as many will operate from 90 to 250 volts and 50 to 60+ hz with no change in output.

2) Is the peak output current rating of the supply at least as great as the peak current consumed by the transceiver? More is better. Don't forget to add in the current for any accessories that you may want to run from the same supply.

This is over rated. I used a RS-20 for nearly 20 years heavily with 4 different rigs and it never had a problem properly feeding them. A 20 amp supply does not hit a brick wall at 20 amps. The 20 amp rating is for 50% duty cycle which is SSB is never reached unless digital for long transmissions at full power. Also none of the radios I checked actually drew full rated amperage. Usually the draw less. Manufacture rating is conservative because it is better to rate a rig at say 22 amps and have it draw 18 or 19 than rate it at 19 and have it draw more. 

3) Is the supply linear or switching? Each has its advantages. Switching supplies are smaller and lighter for the same output rating but they can generate RFI (RF Interferrence to your receiver) if not well shielded and filtered. The closer your antenna is to the supply, the more of a concern this will be. Switching supplies usually contain a fan which can create acoustic noise in the shack. Linear supplies are larger and heavier but are not likely to generate any RFI. My personal preference is for a linear supply if I don't have a need to transport it.

I have never had a problem with this and my house is full of switching supplies in computers, TV's power adapters for laptops and so no. The fan in my Astron SS30 does not run often and is not very loud and besides I never place supply on desk anyway as I place them under desk on floor but elevated some for proper ventilation. Linear supply cost more to operate and are far more in efficient (power in vs power out)

4) Make sure that the supply has "over-voltage protection". If it doesn't and one of pass transistors shorts then a linear supply is likely to apply 24VDC or more to your transceiver - not good!

You need to hope "crow bar" works on a linear supply or it can fry rig if it fails. With a switching supply output goes to zero if unit fails.
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AA4PB
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« Reply #8 on: November 14, 2011, 11:39:36 AM »

I think you need to read my post again more carefully.

Here's the questions you need to investigate before purchasing a supply:

1) Does the input voltage range match your available AC power?

Not a concern with a switching supply as many will operate from 90 to 250 volts and 50 to 60+ hz with no change in output.

What I said is that you need to check the specs. You can't just "assume" that any switching supply you have will work on 250V.

2) Is the peak output current rating of the supply at least as great as the peak current consumed by the transceiver? More is better. Don't forget to add in the current for any accessories that you may want to run from the same supply.

This is over rated. I used a RS-20 for nearly 20 years heavily with 4 different rigs and it never had a problem properly feeding them. A 20 amp supply does not hit a brick wall at 20 amps. The 20 amp rating is for 50% duty cycle which is SSB is never reached unless digital for long transmissions at full power. Also none of the radios I checked actually drew full rated amperage. Usually the draw less. Manufacture rating is conservative because it is better to rate a rig at say 22 amps and have it draw 18 or 19 than rate it at 19 and have it draw more. 

It certainly might. If you draw in excess of 20A peaks from a supply rated for 20A peak you may find it folding back on the peaks and dropping the output voltage. I don't know why anyone would purposly go out and purchase a supply that wasn't rated by the mfg to handle the peak current you are going to draw.

3) Is the supply linear or switching? Each has its advantages. Switching supplies are smaller and lighter for the same output rating but they can generate RFI (RF Interferrence to your receiver) if not well shielded and filtered. The closer your antenna is to the supply, the more of a concern this will be. Switching supplies usually contain a fan which can create acoustic noise in the shack. Linear supplies are larger and heavier but are not likely to generate any RFI. My personal preference is for a linear supply if I don't have a need to transport it.

I have never had a problem with this and my house is full of switching supplies in computers, TV's power adapters for laptops and so no. The fan in my Astron SS30 does not run often and is not very loud and besides I never place supply on desk anyway as I place them under desk on floor but elevated some for proper ventilation. Linear supply cost more to operate and are far more in efficient (power in vs power out)

Read the posts on e-ham. Some people have had RFI problems with switching supplies. Some complain about the fan noise. I've never seen anyone complain that the electric bill was too high with a linear supply  Grin

4) Make sure that the supply has "over-voltage protection". If it doesn't and one of pass transistors shorts then a linear supply is likely to apply 24VDC or more to your transceiver - not good!

You need to hope "crow bar" works on a linear supply or it can fry rig if it fails. With a switching supply output goes to zero if unit fails.

So the switching supply has over-voltage protection. Some of the cheap linear supplies don't.
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