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Power supplies just keep evolving.

nomadradio

Analog Retentive
Apr 3, 2005
6,938
11,063
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Louisville, KY
www.nomadradio.com
We have been using the various sizes of switchmode "brick" power supplies for some time now. When they'll fit, they provide a superior alternative to fixing the under designed linear-regulated supply and transformer found in a lot of base radios.

Imagine my surprise when my latest restock order arrived. It's the one in the baggie on the right. The size I have become accustomed to is on the left. A glance back at the listing photos reduced the surprise level. Hadn't looked too closely at first.

5D9IZy.jpg


It's smaller in all three dimensions. And the connections are separated. AC-line input on one end, DC output at the other.

VWNNlD.jpg


Inside it's a gutless wonder. Labor-saving measures you can see include plastic-encapsulated rectifier and MOSFET packages. Just like the familiar TO-220, but with the metal tab enclosed in the black body plastic. No need for insulators, just bolt 'em down with a dab of compound underneath. The real complexity is most likely a bunch of surface mount stuff on the underside of the circuit board. Didn't tear it that far down.

Tha1Lv.jpg


Naturally, the first thing to look for is the voltage-adjust trimpot. The customer will want it turned up as high as it goes.

58WilP.jpg


Had to lift the top cover to find it. There's an adjustment hole in the cover, but no trimpot under it.

MyrWul.jpg


Now it's easier to access with a hole punched above the trimmer.

ybfbMr.jpg


Full disclosure: I haven't plugged one in to try, yet. If it's a disappointment, I'll want to pass that along, as well.

73
 

Servers are completely different inside and have no terminal connectors.... At lest all the ones I've seen
 
It says 360 Watt, 12 Volts at 30 Amps. Stamped on the top of the transformer is "12V360W".

No, it's not a Megawatt brand. It's low-price Ebay chinesium. From a USA shipper, though.73

Probably Noisy!? I only use Megawatt S-700-12 series power supplies. They are reliable, Clean, Stackable & work as advertised. USA Customer Service is Excellent.
 
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Need to know if they put out any noise on HF. Via other Post on the Megawatts, discovered eventually that they we spewing horrible racket between like 15-23 mhz real bad when I went back to full HF operation - especially making 15 Meters unusable at my shack. I had run these on 10-11 meter mobiles-as-base and 2 meter mobiles-as-base .... SO they were fine and dandy for a 10~11 Meter operation or anywhere higher like a 2 meter mobile as a base, or on 20 Meters and below for the ham rig ..... despite all their advertising about being "Well Filtered for the Radio Operator in mind". Perhaps they were targeting CB'ers for sales .... which is okay.
 
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The 30 amp supplies I have, (like that pictured on the left) are surprisingly quiet.. I do have a 50 amp unit that looks identical that puts off a tad bit of fan noise, but works well otherwise. I have wondered if changing the fan itself might help.
 
  • Like
Reactions: TRASHYTRAM
Need to know if they put out any noise on HF. Via other Post on the Megawatts, discovered eventually that they we spewing horrible racket between like 15-23 mhz real bad when I went back to full HF operation - especially making 15 Meters unusable at my shack. I had run these on 10-11 meter mobiles-as-base and 2 meter mobiles-as-base .... SO they were fine and dandy for a 10~11 Meter operation or anywhere higher like a 2 meter mobile as a base, or on 20 Meters and below for the ham rig ..... despite all their advertising about being "Well Filtered for the Radio Operator in mind". Perhaps they were targeting CB'ers for sales .... which is okay.

I know there were Megawatt clones or knock offs being sold that were bad at this. This was why buying direct from Megawatt was a must. There was an article on this on some ham web site as I recall.
 
I have a pile of HP 1200w supplies that top out at around 12.7v output. I do prefer to use those. I am good with not hitting 13v etc. They have done well, but with the parts that have to be tacked onto the front to get them to power up reliably, I will wait until I am in the final phase of installation in my shack. They will be on the other side of a wall hung higher than my head. Maybe that will keep them happy!
 

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