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Reviews Categories | Power Supplies | MFJ-4125 Help

Reviews Summary for MFJ-4125
MFJ-4125 Reviews: 72 Average rating: 4.2/5 MSRP: $100.
Description: MFJ-4125 13.8 volts 25 amp switching power supply
Product is in production.
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WA0ZZG Rating: 4/5 Jul 21, 2015 10:18 Send this review to a friend
Quiet RF wise  Time owned: 0 to 3 months
Picked up one at an estate sale, still in the box and plastic, for $70. It is very small and light. My meter shows 13.79V. No RFI problem. Who ever built this for MFJ uses the same design for Yaesu switchers. Plan on bypassing the 120/220 switch and using it for a Hi/Lo fan switch along with a 68 ohm resistor.
K0DOG Rating: 2/5 Apr 29, 2015 11:25 Send this review to a friend
Noisy  Time owned: more than 12 months
In a weak moment (cheap moment) this power supply appealed to my cheap side.
Construction is robust enough.
Noise level is objectionable.
Absolutely would not buy one of these things again
K1EAR Rating: 4/5 Jan 18, 2015 13:15 Send this review to a friend
Hash-free as advertised  Time owned: 0 to 3 months
Had and returned two other switching supplies (Jetstream and Radio Shack), which had awful RF hash, making weak signal use impossible. After a month of heavy use this one seems, as advertised, entirely hash-free. Will probably install resistor some day to quiet the noisy fan, but for now, quite satisfied...
W4KVW Rating: 5/5 Nov 13, 2014 19:30 Send this review to a friend
Does the job well in a small space  Time owned: 3 to 6 months
Must say I was quiet surprised at how well it works for it's size.Got a Great deal on mine used for $25 & it does just what it's suppose to do & takes up such a small space I forget it's even there.The fan runs all of the time but is very quiet unlike many other supplies out there.For my main gear I run an ASTRON RS-70M but the little MFJ handles the jobs I have given it without any problems.I'd say it's worth what they cost even at New prices & for sure at the price I paid for this one.MFJ has a Winner in the MFJ-4125 Switching Power Supply & it's really a Mighty Mite! {:>)
KK5DR Rating: 5/5 Sep 22, 2014 18:25 Send this review to a friend
Good supply  Time owned: more than 12 months
Had mine for several years. Never miss a beat. Fan noise doesn't bother me, as the unit is positioned behind my gear. No need to have it up front, nothing to look at on it anyway.
K6SDW Rating: 5/5 Apr 15, 2014 08:47 Send this review to a friend
Works FB  Time owned: 0 to 3 months
Perfect power supply for portable as advertised!
KD5FLN Rating: 4/5 Mar 29, 2014 12:51 Send this review to a friend
Whisper quiet?   Time owned: 0 to 3 months
Well that is what the advertisment says, "whisper quite fan". I wouldn't say its whisper quite but its not annoying either. I've always liked MFJ products althought they do have this "home made" look & feel about them I never had one fail on me. Currently I'm using the 4125 to pwr my Icom IC-2300h at my QTH and I can run up to full 65 watts full pwr no problem with it... Maybe later I'll be brave enough to do the resistor mod and quiet down the fan a bit, that is my only complaint...
WB4QNG Rating: 5/5 Feb 16, 2014 16:30 Send this review to a friend
great  Time owned: more than 12 months
I have had this thing for 10 years. I actually got more than I expected.
W6NF Rating: 4/5 Aug 3, 2013 20:06 Send this review to a friend
Nice power supply but *very* noisy!  Time owned: 0 to 3 months
The MFJ-4125P runs my Elecraft K3 just fine but I have two complaints. First, the cooling fan is *very* noisy. It amazes me that what I believe to be a standard muffin fan makes that much noise. The first time I ran the rig I thought the white noise that is the cooling fan was coming out of the speaker! The second complaint is that the '4125 is supposed to come with Power-Pole connectors...mine had none in the carton. Not a real big deal because I use them all the time and had some on hand. It is just disappointing that MFJ QC missed something so basic.
WB0FDJ Rating: 4/5 Jul 4, 2013 08:09 Send this review to a friend
Ok, now it's quiet!  Time owned: more than 12 months
Update: I got over being lazy and did the fan mod, putting a 100 ohm resistor inline on the red power lead to the fan. The noise went from very loud to "whisper quiet" while sitting in front of me on the operating position and it still seems to move enough air. I plan to use this for my QRP and low watt rigs. Still recommend it for it's outstanding low RF noise, size and cost. Hey it's MFJ, the first thing you do when you buy their stuff is warm up the soldering iron!
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