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Problem with a mega watt PSU S-700-12 50 Amps

KD2GOE

W9WDX Amateur Radio Club Member
May 30, 2013
952
220
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Buffalo
I'm getting a tremendous amount of noise on 160m and 40m some on 80 and 20
Any one with 1 of these supplies and fixed this
I combined the negative and the Ground that helped a little bit maybe cut it in half..


i have the 36 amp ver and that one is fine i have more then 1 radio and im pushing the 36 amp psu thats why i got the 50...
 
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If you have positively identified the problem to the Megawatt ..... they have a 1 year guarantee. Send it back

no i cant i Messed up and broke the seal installing it in to the case i explained it to him and now he is not responding to my emails..
So now i'm SOL now 'ill try to see if some some CB guys around here it's fine on 27Mhz maybe i can tried it for a 30 amp no more switching power supplies for me..
this legit happens every time i get something in the radio i get a new part and i need to Mess with it for months wasting my time and money nothing just works..
 
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I'll never buy another Megawatt. All the ones I've had started off decent. After a month or more, hash hash hash. They are marketed toward hams, but how many hams want a turbofan whizzing in the shack. Practically every other review mentions how noisy they are. You'd think they'd request the factory install a quieter fan.

I had to bust the warranty seal on the last one to swap out the turbofan.
 
Ive had zero issues so far with my 700/12's. The fans imo are pretty quiet. I have a pair running and they are far quieter than my amp fans and I run EBM papst fans, no plastic.
Yep, mess with the seal and John will stop communicating though when my s1200/12 popped he was quick to send parts.
Gotta remember no matter where your power supply comes from its still full of under performing chinese parts that are designed to fail.
 
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Ive had zero issues so far with my 700/12's. The fans imo are pretty quiet. I have a pair running and they are far quieter than my amp fans and I run EBM papst fans, no plastic.
Yep, mess with the seal and John will stop communicating though when my s1200/12 popped he was quick to send parts.
Gotta remember no matter where your power supply comes from its still full of under performing chinese parts that are designed to fail.

Are you using full HF with the supply? I notice my noise in the lower bands.
 
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Are you using full HF with the supply? I notice my noise in the lower bands.
Im 11m only but hes only having an issue with one of the megawatt supplys so im leaning towards a failed part in the 700/12. As cheap as they are unless you can diagnose and repair it yourself its probably cheaper to replace. Ive never been a fan of switching supplys but I cant afford the heavy iron so its switchers for me for now and so far the 700/12's are working.
 
I have beat my megawatt supplies hard and they all work just fine.
If you break the seals on warranty items you have shot yourself in the foot. Don't blame manufacturer for problems you caused.
 
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I have beat my megawatt supplies hard and they all work just fine.
If you break the seals on warranty items you have shot yourself in the foot. Don't blame manufacturer for problems you caused.

who is blaming manufacturer?
 
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no i cant i Messed up and broke the seal installing it in to the case i explained it to him and now he is not responding to my emails.

Sounds par for the course.

After being told how fantastic these supplies are from him and others when I expressed interest in purchasing one, when I expressed my dismay on the audible level of the fan he went incommunicado in short order.

At least MFJ has a "no matter what" warranty. :whistle:
 
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Sounds par for the course.

After being told how fantastic these supplies are from him and others when I expressed interest in purchasing one, when I expressed my dismay on the audible level of the fan he went incommunicado in short order.

At least MFJ has a "no matter what" warranty. :whistle:
I have 2 running 12 hours a day for the last 3 months and can barely hear the fans 2 feet away. So far i have no complaints.
Mfj is much larger company than megawatt and can afford to eat losses because of people returning items for frivolous reasons or because they were clueless and blew it up.
Unfortunately bad customers made it so John cant accept excuses for accidentally breaking the seals as that would be everyone's reason.
Switching supplys are for those either too poor or too cheap to spend hundreds dollars for a 50 amp iron supply.
 
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Thanks, it's nice to know I'm a "bad customer" because I bought a product in good faith and when I was seeking a solution the seller goes radio silent. :rolleyes:

I'd point you to the review I posted but I'd likely be called a liar too regarding the audio level of the fan as soon as I plugged it in, so if you're interested you can search for it on your own time.

Fact is that I keep my shack quiet enough that I can comfortably listen to radio conversations at a whisper. This supply's fan would not have allowed me to do that. I never ran it for more than a couple of minutes and I hope the op I sold it to is making good use of it. That they're working for you is fine by me.

My gripe is that once the cash was in his hand, everything then became my problem.

Caveat Emptor.
 
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I have 2 running 12 hours a day for the last 3 months and can barely hear the fans 2 feet away. So far i have no complaints.
Mfj is much larger company than megawatt and can afford to eat losses because of people returning items for frivolous reasons or because they were clueless and blew it up.
Unfortunately bad customers made it so John cant accept excuses for accidentally breaking the seals as that would be everyone's reason.
Switching supplys are for those either too poor or too cheap to spend hundreds dollars for a 50 amp iron supply.
Or prefer a bargain that is light weight.
 
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Your gripe was the fan was louder than you liked. If it bothered me that much i wouldnt be seeking a solution, id be seeking a return for a refund plain and simple. If you requested a return/refund within a reasonable amount of time and were ignored you would have every right to be pissed but if you got into a pissing match while seeking a solution over a fan that wasnt defective or broken i might understand the communication cut off but i dont know the details. Sorry you had a bad experience and glad you sold it.
 
When I bought mine, I was aware that the fan noise would drive me nuts. I had plans to swap it out.

I bought the Megawatt because I was lured by other owners reports of no hash. Well, I had no hash for sometime, but it started puking it out. I had other brands do the same thing, even an Astron. Their engineer even called me to discuss it. It's just a theory, but I'm thinking switchers can be affect by strong common mode currents. IDK, I've been fighting RFI here.

Anyway, I've jumped off the switcher train and will remain linear.
 

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