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Product Comparison: Amazon 30 amp switching supply vs. MFJ-4275MV
- Thread starter Moleculo
- Start date
I first for a meanwell 23amp unit it gave me hash like notomarow it made people almost impossible to hear..
Then i got the megwatt 12-400 unit it is clean and i love it. Comparing it to a 30amp linear supply I have I cannot tell the difference..
I would like to put two of these units in parallel do I have to put diodes on the negative and positive or just on the positive?
Then i got the megwatt 12-400 unit it is clean and i love it. Comparing it to a 30amp linear supply I have I cannot tell the difference..
I would like to put two of these units in parallel do I have to put diodes on the negative and positive or just on the positive?
I would like to thank tba02 for reminding me of this power supply. I've been tearing the shop apart and can only find a power cord that is 3 wire and 16guage. I'll only use about 2 ft. Am I safe??
I can't believe will all the crap I have accumulated that I don't have a better power cord to sacrifice.
I can't believe will all the crap I have accumulated that I don't have a better power cord to sacrifice.
Another question, attempting to examine the images on Amazon I'm left baffled at the input and output terminals and exactly where they are on the unit. I just see a bunch of terminals in a row... When I use my 3 wire cord will I be hooking up all 3 wires?? I have a black negative, a white positive, and a green ground.
That row or terminals is the input and the output. there should be some documentation with the unit showing which is which. It is likely able to be wired for either 120 or 240 volts input and will have wire terminals for each as well as for the 12 volt output. Your three wire AC power cord would be for 120 volts input and the BLACK wire is AC hot, the WHITE wire is AC cold, and the GREEN wire is for chassis ground.
Here are a few pics. The input voltage selector is at the right side with the terminals facing toward you
Here's a close up of the selector.
The terminals are designated by symbols stamped on the case on two of my 30 amp psu's and printed on the case in my older unit. The the two from the right are the terminals for the AC input and the next is the ground. The next three are negative DC output. The next 3 after that is the positive DC output. BTW, the trimmer is outside the case on the left side of the terminals. I adjusted mine to put out approximately 13.8 volts. The trimmer is beside that green LED pilot light.
Here's what I did with one of mine that I'll use on my B3016 amp. I just cut a piece of aluminum casing and riveted it to the case. I attached two binding posts(one red and one black) and I connected a wire from the positive terminal to the red binding post and another wire from the negative terminals to the black binding post.
Here's a close up of the selector.
The terminals are designated by symbols stamped on the case on two of my 30 amp psu's and printed on the case in my older unit. The the two from the right are the terminals for the AC input and the next is the ground. The next three are negative DC output. The next 3 after that is the positive DC output. BTW, the trimmer is outside the case on the left side of the terminals. I adjusted mine to put out approximately 13.8 volts. The trimmer is beside that green LED pilot light.
Here's what I did with one of mine that I'll use on my B3016 amp. I just cut a piece of aluminum casing and riveted it to the case. I attached two binding posts(one red and one black) and I connected a wire from the positive terminal to the red binding post and another wire from the negative terminals to the black binding post.
I've gotten a lot of help here, I can do no less. Glad to be of assistance.
From the looks of it I would say the first three terminals from the left are all the same, positive voltage out. The next three are negative voltage out. The next terminal labeled with the schematic symbol for ground is for the GREEN wire from the AC power cord. The terminal labeled N is for Neutral and gets the WHITE wire from the AC power cord and the last terminal labeled L is for Line and gets the hot wire in the AC power cord which is the BLACK wire. Nice to see the 120/240 switch. A lot of units need to be wired differently and have no such switch.
An update that folks might be interested in: I've found some hash from the inexpensive supply on the upper part of 75 meters. It's still not nearly as annoying as the MFJ supply, but it is there and it is audible. Here is a screen print from NaP3 showing it:
I think I'm going to order one of these MegaWatt supplies from Amazon that the Chinese units are copied from and compare the difference:
Amazon product ASIN B00JZBE97U
P.S. If you ever wondered what a Plasma TV looks like on a scope: take a look at the screenshot at 4.020 Mhz
I think I'm going to order one of these MegaWatt supplies from Amazon that the Chinese units are copied from and compare the difference:
Amazon product ASIN B00JZBE97U
P.S. If you ever wondered what a Plasma TV looks like on a scope: take a look at the screenshot at 4.020 Mhz
I recently purchased one of the Chinese units off of ebay. There is zero hash working perfectly with my cobra 29.