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Reviews Categories | Power Supplies | MFJ-4245MV Help

Reviews Summary for MFJ-4245MV
MFJ-4245MV Reviews: 66 Average rating: 3.0/5 MSRP: $150-200.
Description: Switching and Non-Switching Power Supplies
Product is in production.
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N4ZAW Rating: 4/5 Dec 1, 2014 09:13 Send this review to a friend
I changed my mind about this supply!  Time owned: more than 12 months
After owning this supply for as long as I have, I figured it was time to re-review it. I gave it a "1" the first time, only because of MFJ's unmatchable 'unconditional one year guarantee' -- which I obviously THOUGHT I had to use... I had to switch the second one out with my garage supply (where I like to work on radios and such) because it tripped-out at 30amps. And yet, it has been ROCK-SOLID out there for five years, sees daily use! Since 2009, and has been "rode hard and put away wet"! It has been subjected to repeated short circuit shut-downs, always resets, and comes back swinging! The issue with running it in the radio room might've been RFI caused by a defective filtering from my Yaesu FT840, but I'm still not certain of that. I don't think I could rely on it as a shack supply because of that issue and the fan that sounds like a "Wright Whirlwind", but I must admit -- though it trips "RIGHT NOW" when a dead short is detected, it has NEVER tripped when placed under consistent high demand (in the garage, anyhow)! It responds very quickly if you touch the outputs! It's a "keeper". Still, I am only raising that original "1" to a "4" instead of "5" because the fan is very loud for a voice communications environment.
KU4AA Rating: 0/5 Aug 23, 2014 18:50 Send this review to a friend
DO. NOT. BUY. OR. USE. THE. MFJ-4245MV.  Time owned: more than 12 months
Please, if you value your expensive ham radio equipment, do NOT buy the MFJ-4245MV power supply. If you are one of the owners of this power supply, PLEASE take it out of service immediately!!! You are playing a dangerous game of chance each and every time you use this power supply. I am dead serious, and wish to warn you before you kill your radio equipment.

I came out to the shack this evening to see what was happening out on 20 meters. I reached over to flip the switch on the MFJ-4245MV, and noted that the meter was indicating around the 13.8 volt level. I then pressed the power switch on my Yaesu FT-847 to bring it up. Immediately, I heard a loud pop from the power supply, the meter pegged high, and the panel lights and fan indicator instantaneously became VERY bright. As I already had my finger near the FT-847 power switch, I quickly punched the switch to kill power on the transceiver--but I suspect that the damage is already done. I will need to wait a couple days to access another power supply to determine if the transceiver is fried or not.

As for the power supply, I removed it from the shelf, repowered it with only my Fluke meter attached, and it drove up to 31.16 volts and begain a high-pitched squeal (likely the switcher). I could probably fix the power supply myself, but what is the point? Like Ian, KC2YXU, stated earlier, I will never be able to trust it to power anything, especially if there is the chance that it will overvoltage for any reason. Many of the reviewers here had a momentary short circuit which precipitated the failure; I simply turned my radio on. If this power supply can be damaged with only a 2-3 amp surge, and kick up to such a horrendously high voltage that it will kill a transceiver, why would I want to fool with it?

Why would YOU want to take that chance?

Please, don't buy this power supply, and please stop using it, for your own sake. I had mine for a year, and it worked flawlessly except for one time. One time is all it takes.

Jim, KU4AA
AA2SM Rating: 0/5 Mar 9, 2014 22:21 Send this review to a friend
Sounds like a lawn mower  Time owned: 0 to 3 months
I had owned a 4225 and had superior performance from it over the years. when I dropped it in my shack moving things around, I decided to get the 4245 model. I really hate to say negative things about a product, sometimes thinking its me. But I can honestly say that this is a real piece of crap. From day one the fan was super loud. I started to get a hum noticed in my headphones which increased as a higher voltage was applied. Finally at around 13 volts it sounded like my lawn mower in my headphones and on the air. Had three other hams in a row tell me I had a loud hum along with my transmit. My forte in radio is cw and boy this was annoying I wished I read these reviews before I purchased it. My only thoughts now is that there should be a law against producing such a monster which could potentially ruin your rig. Went back to the 4225 and everything is quiet and great again. I hope that my fellow hams that gave this a 5 rating, have all the luck in the world with it. Yes its big and some would say pretty. So was the Titanic
VK2BJP Rating: 0/5 Mar 4, 2014 12:31 Send this review to a friend
Piece Of Junk  Time owned: 0 to 3 months
Bought this ps switched it on, it ran for 10 minutes @ 21 amps when I try to increase power on the tx that is draw over 21 amps the ps thinks it overloaded and shuts down, very poor quality.
This is the second piece of junk I've bought from MFJ, I won't be caught again
AI4HO Rating: 5/5 Feb 27, 2014 19:41 Send this review to a friend
Ten years still goin strong  Time owned: more than 12 months
I have had my MFJ-4245MV power supply for ten..almost 11 years now. It still keeps chuggin along, no hash, no noisy fan, no RFI issues..nothin of the sort. I find this power supply to be robust, and with the adjustable voltage output, you can't go wrong. This power supply has powered a variety of rigs over the years, Kenwood TS-570 D(G), Yaesu FT-897D, 857D, Icom 706MKIIG, to name a few.

I currently have my MFJ-4245MV loabed out to a relatively new ham who needed a metered power supply, I was one of a couple and the only one who lived near by to have a metered power supply..the MFJ-4245MV. He has been using this power supply for two or three months now with no issues what so ever. That said, these are relatively small and light weight and easily transportable, great for field day use, mine has seen at least 9 field days, and barring any unforseen accidents..will likely see quite a few more field days. These are not that costly to purchase and are well worth it at any price. I have recommended these power supplies to my friends and other hams I have met in my 20 years as a ham. Thanks to all who have taken time from their busy schedules to read my post. I pray you all have a great day.

73 de Mark
WV2M Rating: 2/5 Feb 27, 2014 17:57 Send this review to a friend
RFI Issue  Time owned: 6 to 12 months
I bought the power supply several months ago as a replacement for the MFJ-4125 that gave up the ghost after 5+ years of operation. My major complaint with the 4145 was its noisy fan (not defective but a design characteristic of the fan).

However, this deal killer for me is that I discovered that the MFJ-4245 interferes with my Chamberlain garage door opener remotes!

I had been suffering with poor remote performance for months and after trying everything on the garage door front I finally started to look for local sources of interference. The remotes operate on 315 mHz. After Googling garage door RFI issues I came across some posts that implicate computer switching power supplies as a possible source. I unplugged my computers but no change. Lastly I unplugged the 4145 - BINGO! The remotes have full range again!

I called MFJ tech supplort to report the issue. They never heard of this but noted it.

I have since replaced my power supply with an Alinco DM-340MV linear supply (very hard to find since they no longer export the supply to the USA) and could not be happier.
AL7B Rating: 0/5 Oct 31, 2013 07:25 Send this review to a friend
No Good  Time owned: 0 to 3 months
In service for 1 hour with 1 amp load. Then POP and the load was toast. Saved the knob and binding posts and threw the rest into the trash.
VK6SMK Rating: 1/5 Oct 30, 2013 21:43 Send this review to a friend
Overvoltage at output  Time owned: 3 to 6 months
It is only when it happens to you that you look to see what others have experienced.
I wish I had read reviews before now.
I have seen the video clip on the net and read whats on here.
I had the exact same thing happen to me a few days ago. The PSU went into overvoltage at the output around 34V. It blew up my Yaesu radio's protection diode, thankfully it was in the circuit. The radio was not even on. It also damaged other equipment. The agent in the USA has been very helpful. For a few dollars fitting similar protection in the Yaesu circuit would be a good idea. Not very happy with this at all.
AE8MM Rating: 0/5 Oct 20, 2013 15:42 Send this review to a friend
Dead out of the box...  Time owned: 0 to 3 months
I've had good luck with previous MFJ products and didn't buy into the negativity that is usually attached to the products they make.

My luck ran out with this power supply.

Out of the box, poor workmanship could be seen. There were several wires pinched between the front cover and the case.

Not seeing any other obvious defects, I put a Yaesu 2800M onto it and plugged it in. Nothing...

No lights, No volts, no nothing. Checked the fuse and it was good. At this point rather then trouble shoot it, I elected to just return the product.

Here's the fun part.

So I was going to just exchange the supply for another. The salesman wanted to check the returned supply first. He plugs it in and BAM!, sparks everywhere.

At that point I decided I was going to exchange for something other then a MFJ supply.
W4KHZ Rating: 1/5 Jun 21, 2013 14:24 Send this review to a friend
Waiting for repair from MFJ X 2  Time owned: 6 to 12 months
DON'T BUY IT. I am waiting for it to return from MFJ for the second time. First time it took out 2 transceivers that cost some serious money to repair,not to mention that I have paid the shipping to and from MFJ twice. Same problem that most have experienced. NO PROTECTION !
When I talked to MFJ they said they would fix their product but no help paying for the radios that were damaged.I've had this P.S. for 11 months. When it comes back I'm getting rid of it, Only 1 month left on warranty...Fan noise not a problem for me, P.S. is under the bench.
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