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MegaWatt vs. Chinese Imitation 30 amp switching power supply comparison

Try calling John up and tell him what you're seeing. Maybe you got a bad one. Or maybe your experience can help product improvements.
He said it was a ground loop. I haven't even powered anything with the supply, just powering up the supply itself. I guess I will try isolating the plug ground and see what it does.
 
I bought one of the other brands just to see how they worked. I hooked it up and put a load on it. It was primitive load but it works. I used car head light bulbs mounted inside of a metal down spout and have a centrifugal blower moving air through it. I monitor the current and flip switches until I get the current load I want. The "Other Brand" had more birds than a pigeon feeding station in New York City. I modified the test load so I could Pulse load the supply 10% or 50%. The 50% load caused unstable voltages with a two volt variance. I took the megawatt unit and subjected to the exact test and the maximum variance I saw was only about 250 Milli-volt change. No birdies either.
I was some what puzzled by the test result and opened them both up. The cheapo unit lacks a substantial amount of power filtering compared to Megawatt unit.
It takes more than a few Capacitors to give a good regulated output. Compensation networks in the switching circuits have to be tuned in for proper regulation. To much compensation and it will ring and oscillate, too little and the voltage will sag and slowly recover. I'll look and see if I can find all of my test results.
 
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I bought one of the other brands just to see how they worked. I hooked it up and put a load on it. It was primitive load but it works. I used car head light bulbs mounted inside of a metal down spout and have a centrifugal blower moving air through it. I monitor the current and flip switches until I get the current load I want. The "Other Brand" had more birds than a pigeon feeding station in New York City. I modified the test load so I could Pulse load the supply 10% or 50%. The 50% load caused unstable voltages with a two volt variance. I took the megawatt unit and subjected to the exact test and the maximum variance I saw was only about 250 Milli-volt change. No birdies either.
I was some what puzzled by the test result and opened them both up. The cheapo unit lacks a substantial amount of power filtering compared to Megawatt unit.
It takes more than a few Capacitors to give a good regulated output. Compensation networks in the switching circuits have to be tuned in for proper regulation. To much compensation and it will ring and oscillate, to little and the voltage will sag and too slowly recover. I'll look and see if I can find all of my test results.

Dynamic load testing is what matters in communications duty ESPECIALLY where any form of amplitude modulations is used including SSB. IMD can go all to hell if the power supply voltage is wandering all over the place with varying loads on voice peaks. Most people do not understand this or even care but responsible operators do.
 
So, I kinda hate to ask, but did John aka Mr. MegaWatt sadly die or something? He hasn't been seen on this website for over 33 weeks at time of this post!!

"Megawatt was last seen: 33w 1d ago"

I'm just wondering about the loud fan noise and if it ever got resolved? :(
 
Hello, yes the S-700-12 is 1/2 the volume it used to be and soon the S-350-12 and S-400-12 will be almost silent. Above ground????? They are buying 100s of power supplies a week. Somebody is shipping them:)
Thank you,
John

Wanted to make sure he was above ground. He is. Those new specs look great.
 
Oh yes, he's above ground. Each time I've ordered a PS from him I receive an email with ship date, delivery confirmation number, and a "thank you".

Upon receipt of PS I send him an email acknowledging receipt of the PS. Within a day or two I receive and email back from him..

Anytime I'm talking on my AT-6666 set up as a base radio I'm using two of the S-400-12 PS's...one to run the radio and one to run a two-transistor amp.

Bottom left corner of picture. (y)

414374941.jpg
 
Oh yes, he's above ground. Each time I've ordered a PS from him I receive an email with ship date, delivery confirmation number, and a "thank you".

Upon receipt of PS I send him an email acknowledging receipt of the PS. Within a day or two I receive and email back from him..

Anytime I'm talking on my AT-6666 set up as a base radio I'm using two of the S-400-12 PS's...one to run the radio and one to run a two-transistor amp.

Bottom left corner of picture. (y)

414374941.jpg

Great looking setup!!
 
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Thinking of moving my 10-12 amp (DF1724) big old power supply to the shed in NC to go with the rig I'm going to leave there and ordering another S400-12 (tip left in pic) to replace it (I have one in use for my HF rig and my 4 pill). Smaller is better when working with tight shelves that I have currently. DF1724 on bottom right next to the Alinco HF. Also be nice to lose the front power wires that are sitting there.


A0482788-CE85-4532-B962-858366DF14F2.jpeg
 
Thinking of moving my 10-12 amp (DF1724) big old power supply to the shed in NC to go with the rig I'm going to leave there and ordering another S400-12 (tip left in pic) to replace it (I have one in use for my HF rig and my 4 pill). Smaller is better when working with tight shelves that I have currently. DF1724 on bottom right next to the Alinco HF. Also be nice to lose the front power wires that are sitting there.


View attachment 34423

BTW, lookin like a nice setup! (y)
 

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