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Reviews For: MFJ-4275MV

Category: Power Supplies

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Review Summary For : MFJ-4275MV
Reviews: 22MSRP: 249.95
Exclusive HashSquash RFI Filter
75 Amps Peak, 70 Amps Continuous
4 - 16 Vdc Adjustable Output
Battery Charging Circuit
Input 110 VAC or 220 VAC - Selectable
Back Lit Volt and Amp Monitor Meters
Output Protection:
Short Circuit, Over-temperature
Overload with Auto Re-start
Fault Warning LED Indicator
Multiple Output Connector:
75A 5-Way Binding Post
40A 5-Way Binding Post
35A Anderson Power Poles (2 pairs)
15A Cigarette Lighter Socket
10A Quick Connect Terminals (2 pairs)
MightyLite - only 10.5 lbs (package weighs more)
One year No Matter What Limited Warranty
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
WA6ZHE Rating: 2019-02-17
Not Too Great Time Owned: 6 to 12 months.
I bought this one to power my ALS-500M, which it appears others have done as well. It worked fine until just the other day. I was listening on 40, linear was powered off, but the 4275 was on. In fact I had not transmitted for at least 30 minutes. I heard a little "plink" which sounds similar to an auto switch powering off. The Fault light came on, and I attempted to power it off. No way, no how, would this power supply power off until I pulled the AC plug. After waiting about an hour, I plugged the AC in again, and right off the bat the supply came on, with the fault light. Of course I had made sure the power switch was still off. Will update if I ever figure this out. This only powers the linear amp; my Kenwood is on an Astron power supply.
K3MOV Rating: 2018-01-31
Unusab!e!! Time Owned: 0 to 3 months.
Bought this to ensure 200 watts from my new TS 480HX. Was going to put it in line for a test drive but decided to try with my existing IC 7200 first. What a disaster! Nothing but birdies, hash and a few helicopters throughout entire range of 7200. Ordered an Astron from Gigaparts. Keeping my fingers crossed as Astron seems to be having similar problems as M F J recently.
KS4AA Rating: 2016-08-24
A good fan replacement for MFJ-SMPSU's that use the 3" fan. Time Owned: more than 12 months.
Did a lot of research for a replacement fan that was super quiet and low-cost that would fit the same mounting holes. And I found one! Got it off AMAZON... ARCTIC's actually a fan for a PC case. It fits perfectly. It also has its own heat sensor probes. To wire it, connect the YELLOW to POSITIVE and BLACK to NEGATIVE. The connectors are different, so I simply cut off the existing connectors, leaving a few inches of wire, then spliced the new fan wires. I put a piece of heat-shrink over the spices. Be sure to face the decal towards the grill. I inserted the probes into the heat sinks. That's it!
N4PAL Rating: 2016-02-25
Great Performer Time Owned: 0 to 3 months.
The early versions of this power supply did not get the filter that has ben update by the factory. I have had this one in operation for 3 months.
Overall this power supply has been a great performer with no hash noise on any bands.
The difference I see internally is the placement of two very large iron core chokes - one around all positive wires and negative wires leading into the main internal voltage connection board. I tested with with scope and see almost noting across spectrum. I suggest that anyone have a noise issue should install the cores. Assume value.
KK2DOG Rating: 2016-01-25
Nice ! Time Owned: 6 to 12 months.
I've been using one to power my Ameritron ALS-500M in the shack for about a year now and have experienced no issues whatsoever.
N5MNO Rating: 2016-01-25
hash on bands Time Owned: more than 12 months.
I get a 360 hash sound on all bands..tried an isolated gnd and dedicated 120vac no help its in the supply comes and goes terrible. would not recommend
WA4RX Rating: 2015-12-05
Do not recommend purchasing Time Owned: more than 12 months.
This is my second one. The first was replaced my MFJ. It is not as bad as the first one but still sends pulsating signals over 80, 40, 20, 15 and 12 meters. I isolated everything in the shack and still had a problem. I took it to FL where I winter and it keep on doing the same thing. I am only sorry that it is too light to use as a boat anchor.
I am not selling it as I do not want to wish the problem on anyone else.
NZ8J Rating: 2015-06-01
Make sure.... Time Owned: more than 12 months.
I've used these power supplies over the past few years to power an ALS-500 and always had good results with minimal to no "hash" noticed in the receiver, certainly not to the degree of rendering the receiver useless. A few years ago I sold one to an individual who emailed that it was putting out so much hash he couldn't use it. I was bewildered but told him to send it back for a refund. Shortly after he emailed that he hadn't noticed the warning not to use the rear terminals to power the radio, that they were for battery charging. Just saying, make sure the front terminals are used to power the radio. Not saying its the issue in this instance but I thought it a good time to mention it.
I rated it a 4 and not 5 simply due To the occasional fan rattle, it could be smoother.
Tim NZ8J
W0DLR Rating: 2015-05-31
RF Hash Time Owned: 6 to 12 months.
I have had two of these, they replaced the first one with another new one, which is just like the first one....hash up and down the bands. I have sent them an email asking for them to do something with it or about it. It produces the power ok the run the ALS500 but it isn't much good when the receiver is rendered useless. Rig is a TS450s btw.
Hopefully they can hit upon something to make them work.
N7BOO Rating: 2014-12-14
Great PWR Supply Time Owned: 0 to 3 months.
Well …. let’s see, I purchased an MFJ-4275MV, it arrived on time, packaging/carton excellent, no rattles, fired right up. Now about the RF hash that some are reporting. I haven’t had any RF hash issues period. I use the power supply for VHF/UHF/HF, and I haven’t experienced a single RF hash issue of any kind. YES, I know what RF hash is and sounds like after 35 years of being a Ham.

The problem with a lot of folks is that is they mistake where the RF hash is really coming from and inadvertently blame the power supply, or simply because it carries the MFJ name.

All those computer monitors, PC’s, routers, SWR/Watt Meters, auto tuners, frequency counters, sound card interfaces, weather stations, police scanners, 50 inch TV’s, entertainment equipment, other ham accessory gear, and other devices you own, generate noise/RF hash. Don’t forget all those damn unregulated wall warts that come with all this ham gear and entertainment equipment you purchased, they all generate more noise/RF hash than a freight train at midnight running through a monastery.

So don’t be so quick to blame your MFJ-4275MV switching power supply, unplug all that other RF generating equipment first, and by the way, check to see how much RF hash your neighbor is generating, like police scanners hooked up to an outdoor antenna. By the way don't overlook the dollar stores automatic doors that put out RF hash everytime the doors open and close, they even set off radar detectors.