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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
AC0DB Rating: 2006-02-19
Compact and Steady Time Owned: 3 to 6 months.
I use this power supply with a Yaesu FT-8800R and an MFJ-890 DX Beacon Monitor. This power supply fits the bill for running these pieces of equipment perfectly because the FT-8800R runs off of the front posts, and the DX Beacon Monitor runs off of the handy pressure terminals on the back of the unit. In this configuration, I do not have to crimp and solder the thin wires from the DX Beacon Monitor to ring terminals and make an ugly stack with the FT-8800 terminals on the front of the unit. This is very handy.

The output of the unit is very steady and I don't have any problems with the unit electronically. The fan that runs continuously on the back of the unit is a bit loud, and in fact it is louder than the fans in my PC. I may retrofit the fan with a temperature controlled resistor in the future. My suggestion to MFJ would be to temperature control the fan, or put a quieter fan in it.

Other than that, this is a great unit that will probably last for years. Recommended - especially for the price.
W6FO Rating: 2006-02-03
A little disappointed Time Owned: 0 to 3 months.
Purchased on 2/2/06 from GigaParts.com

I purchased this power supply based mostly on the reviews here. I needed a new power supply for my HF rig and could not afford the high cost of a matching linear power supply for my rig.

Most of the reviews here highlighted low noise, both RF and from the internal fan. Maybe I got a fluke but, on my unit, I find the fan to be quite loud and can hear it in the other room some 500' from my shack. It is by far the loudest piece of equipment now in my shack. The three fans combined in my overclocked PC are quieter than the one small one in this power supply. I may have to install a resistor to slow it down or just send it back to MFJ.

Otherwise, it is working fine and a big improvement over the electrical noise my ancient linear was putting out.
VU2YK Rating: 2005-11-04
NO RF Hash !! Time Owned: 0 to 3 months.
I was sick of Switch mode supplies that I bought elsewhere. Here I am on a trip to US with my ICOM 706 Mk2G and first thing I did was to order a 4125 and 902 Tiny Travel Tuner from Giga Parts.

I am extremely pleased with this supply. Absolutely NO RF Hash. I am a CW guy and a weak signal digger. Here in US ( Raleigh/NC ) I use the 4125, 902 and 5$ 40 M dipole thrown on two trees in backyard and work all over world on all HF bands ( Except VU !!)

Good dependable piece of equipment for the money spent, all of them 706Mk2G, 4125 and the 902. If you operate a lot of CW consider the 500 HZ filter FL 100 for your 706. It really helps. I would like to hear from other hams about 500Hz Vs 250 Hz filter.

And if buying a 902 and planning multiband operation on same antenna using ladder line , consider the 902-H, the one with the 4:1 balun.

73s

Rahul
W4/VU2YK
HB9PJT Rating: 2005-06-03
Wunderfull Time Owned: more than 12 months.
I am very happy with the power supply. Perfect for vacation - you will not find a smaller or lighter one! Absolutly no noise, I did test with the antenna just one meter away of the power supply on all SW bands. used allmost every day and so far reliable.
NZ5L Rating: 2005-06-03
noisy, unreliable Time Owned: more than 12 months.
When I first got it it had been set to 220V, so would not deliver the 18-20A needed for full cw power. After that, performed OK for about two years, presently will throttle itself back to a 5A output for no apparent reason, even with a near 50ohm antenna load on the xcvr. When this happens, the rig nearly shuts down. I have cleaned it often so it's not dust. Currently using it for receive only, plan to go back to a real iron supply, also quieter and less hash. Maybe some of these work OK but I would avoid this one.
AD5X Rating: 2004-07-19
Compact and quiet Time Owned: 0 to 3 months.
I picked one of these up at Dayton this year, and it works great. Very quiet, light and compact. Both the AC input, and front & back DC outputs are very well filtered. MFJ had an earlier version of this supply (same part number) that was twice as deep. This supply is 5.5”x2.5”x5.75” (even recent MFJ literature shows the old larger dimensions). I replaced the rear low-current connector with a pair of Anderson Powerpoles, since I like pulling high current from the back of the supply.

Phil - AD5X
PE3HMP Rating: 2004-07-19
what a cheap junk Time Owned: 6 to 12 months.
What were they thinking when they made this thing, the - connector on the front is connected thru a bolt by a metal strip on the chassis and inbetween it is a piece of board that does not make contact, christ did'nt they have two inch of cheap wire ??
You cant putt 25Amp thru this and expect it to last.

The owner had this PS for les than a year before it broke down and brought it to me for repair.

And yes, this is another one of MFJ's products for the wastebin, i'm not going to putt more time in it seeing how they made it it is asking for problems.
KD5MDO Rating: 2004-07-13
Compact and quiet Time Owned: 6 to 12 months.
I've owned this little power supply for 7 months now with no problems. The fan is quiet as mentioned by other reviewers. Good value for a low cost. I'm probably the only female in a 100 mile radius that was happy to receive a power supply for Christmas!
K7TTI Rating: 2004-03-18
Great unit Time Owned: 0 to 3 months.
I've had this power supply for over a month and it performs flawlessly. The fan "noise" is less than the FT-8800R's fan noise to which it is powering.
I'd recommend this unit to anyone needing a very small, lightweight, 25 amp supply. The desk space gained is another reason I like this unit.
I have not experienced any RF noise at all and it seems to be built as well as any of the other power supplies I've had or built.
W7HV Rating: 2004-03-07
Best lil switcher Time Owned: 6 to 12 months.
I bought this for portable use and is the only switcher I've tried that generates no HF hash on close-in compromise antennas used during typical portable ops. Fan is somewhat loud but putting a 50 ohm resistor in series with it makes it inaudible and the supply is still cool as cuke running 100W CW.

It's light, small, inexpensive, and works FB. Couldn't ask for more.

----------------------
Earlier 5-star review posted by W7HV on 2003-09-21

I have used a number of switching power supplies for portable ops. All of them produced hash to one degree or another on the lower HF bands when using close-in compromise antennas, including the Alinco DM330MVT. This MFJ supply does not. It's small and light and about the only drawback is the fan is a little loud. I put a 1W 50 ohm resistor in one of the fan leads and it quieted it down to a whisper. I tested it by hooking up a couple of rigs that together draw 5 amps on RX and over 20A on CW transmit. It ran fine through many longwinded CW QSOs getting only moderately warm.

Lou W7HV