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Reviews For: MFJ-4125

Category: Power Supplies

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Review Summary For : MFJ-4125
Reviews: 75MSRP: 100.
Description:
MFJ-4125 13.8 volts 25 amp switching power supply
Product is in production
More Info: http://www.mfjenterprises.com/products.php?prodid=MFJ-4125
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
15754.2
K5WW Rating: 2004-03-07
R.I.P.... Time Owned: more than 12 months.
Well boys and girls, mine just died after almost three years of service.

For the past two years it was powering my HF rig, never exceeded the nominal current rating, but today it decided to quit. In the middle of a contest, not funny! And I was only working stations here and there, so it can't have overheated.

Why, I don't know. I cleaned it right after New Year's day, so it was virtually dust-free when I opened it up. The internal fan sucks in a lot of dust - something we in dry south Texas have plenty of - so I cleaned it every 6 months or so.

I replaced the internal fuse, but every new one keeps blowing. The internal fan - running on 12 Volts - still spins momentarily until the fuse blows, so it's not entirely dead. At 40 bucks an hour for repairs plus shipping I'm not going to have it fixed though!

Instead, I'll just get another one. They are cheap, and despite the Voltage setting mistake at MFJ (see my earlier review) it has served me very good. It has survived many stressful RTTY contests at maximum load.

The fan noise that some report doesn't bother me at all; it only becomes apparent when I turn off everything at the end of the day.

As far as RF hash is concerned I must say that this one is (or "was") pretty quiet: I did a test on a battery one day when we ran out of power (something else we have more than enough of in south TX...) and really didn't hear any difference on the low bands.

All in all it's an "OK" power supply. It just died too soon, and I thought I'd share that.

K5WW

W4KRL Rating: 2004-02-08
Great supply Time Owned: 6 to 12 months.
I normally run on a trickle charged battery. I don't hear any increase in noise or hash when switched over to this supply. Fan is very quiet. This is a great supply for travel and portable operation. Makes a nice companion with the MFJ-902 travel-sized tuner.

Would like to see Anderson PowerPole connectors built in but is easy to make an adapter.
NO9E Rating: 2004-01-26
Lightwaeight, cheap, some hash Time Owned: 3 to 6 months.
I purchased 4125 for travel because of its size. Hash is below noise with outside antennas but heard somewhat on HF with portable antennas. Definitely 4125 is not ideal because of hash but I have not found out anything better giving the dimensions and weight. Samlex was much noisier.

One problem with my PS is that the enclosure is AC hot when used with 220V. Perhaps there is a problem with faulty blocking AC capacitor because this capacitor is hot.
Ignacy
W8OKN Rating: 2004-01-26
Excellent Time Owned: more than 12 months.
Mine has been excellent. I am very impressed.
K0KK Rating: 2004-01-07
Great if size and weight are important Time Owned: 0 to 3 months.
My only complaint is a small amount of emitted RF that appears as an occasional roving whispering carrier in my receiver as it passes by. It’s just above the noise, and probably won’t cause me to miss anything in copying CW or SSB. It’s just a bit annoying. I sent my first unit back to MFJ because of this flaw, and they replaced it with another one that had the same problem. The emission was on 20 meters for the first one, and it’s on 40 for the replacement. I had a Kenwood unit for about a year and never noticed this problem with it, but it’s possible I just didn’t catch it. The fan and output terminals are sturdier on the Kenwood, although it’s also bigger and heavier. The craftsmanship on my MFJ unit is good. However, comparing switching supplies to linear regulated supplies, I’d recommend a linear supply if space and weight aren't considerations for you. The switching supply is complex and therefore more likely to fail. It’s also probably about impossible for most of us hams to fix. Add in the RFI potential, and I think it makes sense to get a switching supply only if you use it portable or have limited room.
AL7B Rating: 2003-08-16
Nice Supply Time Owned: 0 to 3 months.
This is a nice little power supply. I was not able to find any hash anywhere while using it next to my TS-50S. The output voltage is very solid.

Yes, the fan does run all the time but very quiet.

There has been some discussion about the actual size of this supply. Mine is 5.5"Wx6"Dx3"H. The depth measurement includes the binding posts.

The rear has speaker type clips for 5amp output and 5 way binding post on the front for the high current application.
WA7NDD Rating: 2003-05-08
Good but Noisy Time Owned: N.A.
This power supply has worked two ARRL Rtty contests on a 706MIIG and now my FT-920. It has run fine for every thing I do, but I have more and more noticed how really noisy the fan is in my quiet room. Other than that it is a real bang for the buck power supply. I plan on getting an analog supply to replace it. Noise is why I gave it a 4.
73, WA7NDD
N4BRJ Rating: 2003-05-07
Works as advertised Time Owned: 3 to 6 months.
I use this great LITTLE powersupply to feed my FT-100D. No problems whatsoever. Runs nice and cool.
N5MJ Rating: 2003-01-11
light but performs Time Owned: more than 12 months.
This supply is used on a test bench as well as hamfests (general radio supply), field day (powered an IC735), and once took the place of my Astron RS35 powering a UHF repeater.

It's light weight makes it a great traveller. I've experienced no glitches, much less detectable hash than Alinco or Pyramid switchers, max current output at regulated voltage matches rating... And at $99, you can't go wrong.

Try drawing rated current or more, and it gets warm, otherwise cool operation is the norm.

Bottom line: if you need a light-weight 25A supply, this is the ticket. Save your back!
K4ZAU Rating: 2002-12-02
Good things come in small packages Time Owned: 0 to 3 months.
This supply is extremely small and lightweight. I've used it with my HF rig and I get excellent signal reports, so it doesn't seem to put out a lot of hash. I agree with some others who believe the fan should switch on and off as needed; however, it isn't that loud and did not bother me when it was three or four feet away from my ear. Another good product from MFJ.