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Reviews For: MFJ-4245MV

Category: Power Supplies

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Review Summary For : MFJ-4245MV
Reviews: 73MSRP: 150-200.
Description:
Switching and Non-Switching Power Supplies
Product is in production
More Info: http://www.mfjenterprises.com/products.php?prodid=MFJ-4245MV
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00733
N1DAE Rating: 2022-06-10
These are built with a lot of magic smoke! Time Owned: 0 to 3 months.
I was recently given one of these power supplies (SN L30000904) that had been in climate controlled storage at a public safety agency for quite a while. At the time I joked that equipment like this had no place in such an important (even standby) role. Soon I'd learn how accurate that comment was! On my bench I found the unit was brand new and had never even been unpacked. After plugging it in and turning it on (with no load), the power supply ran for about 10 seconds but then shut down. I verified that the input voltage was set correctly, the fuse was still intact, and there were no other obvious problems. Following the directions I waited over 20 seconds, plugged the unit back in, and turned it on a second time. There was an immediate hiss followed by a significant release of the legendary magic smoke... and this unit contained a lot of it! Literally right out of the box this thing burns up?!? I've always taken criticism of MFJ products with a grain of salt. Keeping in mind this wasn't a unit from current stock, from now on I will probably avoid buying anything from MFJ whose failure could destroy other gear... or my house!
WA4CAX Rating: 2021-11-03
Rig killer !!!! Time Owned: more than 12 months.
Why I give this power supply such a poor rating is that it has no over-voltage crow-bar protection....The power supply failed recently and output high voltage DC, much greater than the 12 VDC it normally outputs.....Absolutely destroyed my Icom IC7100.......On these and similar switching mode power supplies I now place a high wattage 15 Volt Zener diode across the output/s to limit the maximum voltage and damage potential......This is particularly important if you connect one of these to a multi-outlet 12 VDC distribution strip.....
W4BUZ Rating: 2021-08-21
Been a good one for sure Time Owned: more than 12 months.
I have had my 4245MV for over 16 years. The only problem that I have had with it is, the rocker switch went out at around the 10 year mark, which was no problem, I put a new switch in it and it just keeps going and going just like the energizer bunny.
N0UYD Rating: 2021-03-30
Noisy Time Owned: more than 12 months.
I have never written a product review before, but I felt inspired to do so due to my wife.
I have had the MFJ 4245 power supply for several years. It has always worked. It has always had a noisy fan. Lately it has developed a grinding noise upon startup that would go away after a few minutes. The fan noise remained. I did not want to do any repairs to this supply.
This morning, my wife was closer to the power supply as I started my morning hamming activities. I asked her to turn on my power supply. She than thanked me. Why did she thank me? Because I replaced the MFJ 4245 with an Astron VS-35M-AP power supply that is a quiet as a can be. My wife rarely thanks me for spending money to replace a device that still works.
W8PP Rating: 2021-03-19
Great Power Supply -23 Years Old Time Owned: more than 12 months.
I must have gotten a great one. I used it almost daily for 23 years. No rf noise. No failures. It's starting to become a "senior citizen" because it doesn't regulate as well as it used to, but not bad enough to cause a problem. I might put it into semi-retirement soon to give it a rest. I have definitely gotten my money's worth out of it.
N7BTH Rating: 2019-02-23
Fan Noise Time Owned: 0 to 3 months.
Many others here have tested the limits of this power supply. I have not as I only use it to power my VHF/UHF Icom for weekly net check in. When set to 13 volts for that purpose the fan runs full speed, even with no load on it. The "variable" part of the fan speed comes in as you dial down the voltage output. Down at about 5v the fan is pretty quiet but at 13 too noisy for me. Will ether need to install a bypass switch or move it farther away from the rest of the station which is inefficient and not very convenient.
W8RLM Rating: 2018-08-26
Intermittent Power on Start up Time Owned: 6 to 12 months.
Less than a year operation and never worked. I find the supply fan light flickers and the device will not start up. However, after several attempts, it finally MAY start up. Interesting how the fan light flickers and that is all she has Captain.
AC6BW Rating: 2018-05-17
Working fine after 4 years Time Owned: more than 12 months.
I've owned this power supply for over 4 years. It powers all of my HF gear. I've had no problems whatsoever with it. I do not push it near its current limit, however, I do operate it for long periods of time, sometimes entire weekends, running high duty cycle modes in contests. The fan noise is not very loud. My tube based linear amp has a louder fan than this supply. I have not had any problems with voltage ripple or hash. I agree with another reviewer, that folks who have had a positive experience should take the time to post a review.
WA2ZQX Rating: 2017-11-21
Noisey Time Owned: more than 12 months.
Failed during first week...loud pop...fuse okay. Returned to MFJ. Got it back five weeks later after a number of calls. It has been good since. Fan noise is very loud...and so annoying. Also have a Powerwerx SS-30DV power supply...very quiet fan, 1/4 the size and no problems. My HF-AMP and Transceivers are whispers compared to the racket made by the MFJ-425MV.
ISOAR Rating: 2017-10-19
Danger Will Robinson! Danger! Time Owned: more than 12 months.
This is an update on my first review. Rating "poor" and not "awful" because it hasn't yet fried anything of mine in the years I've owned it.

Keep in mind that my unit is an older model, and not from a recent production batch.

Today I was in the mood for some hacking, and I wanted to upgrade the meter lighting to white LEDs like the newer models. The incandescent bulbs have always annoyed me with their warm colour, and non-steady brightness.

I first Google-ed to see if anyone else had done it, and only found one comment about the bulbs not looking replaceable.

However, I also found a curious mention of someone else replacing the output capacitors and load resistor. Upon a closer look, I agree, 16V caps always bugged me too that they were not at least 25V, and the load resistor (3W) really should be 10W given its bad location with no cooling, and preferably moved to a position near the fans.

Upon opening the case, I was taken aback by the LARGE number of flying components! There was more to be concerned about too.

Instead of using crimped lugs for the binding post connections, the positive wires (2x 16 AWG, 105 degC) are soldered directly to the binding post screw, making them non-removable. So the front panel is non-removable, and access to the meters to replace the bulbs is not possible.

It was at this point when I realized there were no ground return wires from the board output! Just the frame ground near the AC input.

The ground output binding post is connected directly to the frame (2x 16 AWG). There is a hole in the case next to that likely for the board ground wires to be anchored.

All 45 Amps would have to go through the SEC metal case, to the board mounting posts and M3(?) screws, or the AC frame ground connection (1x 16 AWG)!

Salvageable. Luckily I've never shorted it, nor drawn a heavy load!

I should be able to drill into the top of the meters, and insert LEDs there. Simple matter to clip the bulb wires, and add in a linear regulator for the LEDs to be at a constant brightness.

I'm also planning to add a crowbar, probably external.

Lastly, I'm now looking for a power supply replacement.