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Reviews Categories | SWR & Wattmeters & Dummy Loads | MFJ 854 Help

Reviews Summary for MFJ 854
MFJ 854 Reviews: 6 Average rating: 3.0/5 MSRP: $118
Description: RF Current Meter 1-30MHz
Product is in production.
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KU3X Rating: 4/5 Feb 23, 2018 15:48 Send this review to a friend
Great for trouble shooting common mode  Time owned: more than 12 months
I've owned this meter for about 4 years. I gave it a 4 because I had to calibrate it. It was way off from the factory. Super easy to calibrate, instructions are included in the manual. It's just a turn of a pot.
I have found so many issues of common mode with this tool. A friend of mine had a problem. Went to his house and looked in his back yard. Since the coax cables were so close to the RF field, even though baluns were used,I found it questionable when it came to common mode in the antenna area. Sure enough, I was right. All of the coax cables showed RF of the outside of the shield. Without this meter we would have never known for sure.
I am not saying this is a lab quality instrument, but it is far from junk. I am glad I have it and have found so many uses for it. It's not that I have issues, but this tool can confirm whether you have common mode or not. Remember, just because issues are not showing up in the shack, that does not mean that there is no RF on cables or coax in the shack.
If my unit gets damaged, I'd purchase another in a hear beat.
G3XOU Rating: 2/5 Jul 3, 2017 13:20 Send this review to a friend
More bad quality control  Time owned: 0 to 3 months
I found another problem with the MFJ-854. I was doing some current measurements on a doublet fed with 450 ohm ladder line and I was measuring 0.2A on the 1A range so decided to change to the 300mA range - then the meter hard end stopped!

Having checked the calibration on the 1A range which was correct I found that R10, the series resistor on the 300mA range was the wrong value.

It should be 15k according to the circuit diagram but they've fitted a 2k2 which can't be correct since the 1A range series resistor is 56k so dividing that by 3.333 works out at 16.8K which not being a precision instrument 15k would be the nearest preferred value. The 2k2 gives a full scale deflection of 40mA!

Anyway it is easy to change it as it is close to the outer edge of the PCB. This really is incredibly bad QA by MFJ.
N6YFM Rating: 2/5 Jan 19, 2017 10:22 Send this review to a friend
Quality? Not!  Time owned: 0 to 3 months
I just received mine yesterday.
The battery fits into one half of the case shell.
The circuit board is in the other half of the case
shell. Once you insert the battery, on my unit,
you can not close the case because the battery and
holder will not fit between the sheet metal
and the circuit board.
Next, it is IMPOSSIBLE to open the cable clamp on my unit. I finally used pliers and a screw driver the pry it open. It claims to fit over coax up to 1/2. It will not. You run out of space before hitting .41 inch, so it is a no-go for RG-214 cable.
So, right out of the box, you can not use mine without mechanical engineering re-design.
IK4YNG Rating: 2/5 Jan 23, 2015 13:31 Send this review to a friend
BAD quality control  Time owned: 0 to 3 months
I have just received my MFJ-854, purchased new in the original box.

Upon arrival, it was not working.
A little investigation was showing the Sensitivity potentiometer badly miswired: the two leads were soldered at the extremities, and the cursor lead was disconnected.

Repaired, and still not working...

Then i found that one of the potentiometer's lead was NOT soldered on the PCB where it was marked POT1, but in another hole nearby, a grounding place.
Now, it seems to be working....
What a kind of POOR quality control!

IK4YNG Paolo

AD4J Rating: 5/5 Jun 6, 2013 10:04 Send this review to a friend
A Great Tool  Time owned: more than 12 months
I use it frequently for measuring common mode current on feed lines, both coax and balanced lines. It's also useful for maximizing output from a T transmatch and for finding common mode RFI on input cables.

A couple of nice features are the wide range of currents covered by the 6 ranges and the fact that the meter is calibrated. The lower current scales allow me to use QRP to make measurements - less QRM, easier on finals with prolonged key down, and less danger of RF burns.

As another reviewer noted, there are quality control issues with MFJ products. My first MFJ-854 was defective. However, I've always been able to get hassle-free replacements for MFJ defective gear and this was no exception.

Two small complaints:
1. When using the 3 most sensitive scales, the meter is powered. It will sometimes peg the meter when the auto-cutoff timer expires.
2. There is a single 0-100 scale on the meter, but ranges like 0-3 A and 0-300 ma require a little math (e.g. 50 on the meter using the 0-3 A range means 1.5A).

Overall, I'm very happy with the meter and don't know of any good alternatives for what it does, short of building your own.

de AD4J
VK7JB Rating: 3/5 Nov 3, 2011 19:53 Send this review to a friend
Poor QC spoils a good product  Time owned: 0 to 3 months
This meter promises to be a useful tool for making common mode current measurements around the shack. It's a simple but neat design and is well reviewed on several websites, so I imported it from the US via a helpful online dealer.

The problem with my unit relates to QC and build quality. I noticed that the uncalibrated, high sensitivity scale was not functioning - at all - and adjusting the sensitivity pot had no effect. Taking the unit apart revealed very sloppy soldering and poor attention to detail in the construction of my particular unit. The red QC sticker on the inside tells me it was made in March 2011. A check of the schematic identified the problem with my non-functional low range: the sensitivity pot was completely mis-wired. After refitting the wires to the appropriate leads of the pot, all is fixed and the meter is working perfectly now.

The point is - I shouldn't have to do that. It's not the first time I've had to rework new equipment from MFJ to render it functional, but this is the first time I've felt motivated to leave a negative review. MFJ, please lift your QC so we can enjoy your well-designed products out of the box.

The only negative design feature of the MFJ 854 is the flimsy hinge on the clip-on ferrite toroid used as the RF coupler. There are only X number of times that you'll be able to open and close that little hinge before it falls apart and my suspicion is that here, X is going to be small.

Summary: great concept for a useful tool but needs some attention and a tweak in the design of the ferrite toroid arrangement. This little tool gets 5/5 for concept and 2/5 for execution. I shouldn't have to rework electronic equipment out of the box.


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