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Reviews Categories | SWR & Wattmeters & Dummy Loads | MFJ-250 Dummy Loads Help

Reviews Summary for MFJ-250 Dummy Loads
MFJ-250   Dummy Loads Reviews: 19 Average rating: 3.8/5 MSRP: $59.95
Description: The MFJ-250 Versaload proides a versatile method of loading a RF transmitter
Product is in production.
More info: http://
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K6BRN Rating: 3/5 Nov 6, 2017 18:16 Send this review to a friend
Good for what it is...  Time owned: more than 12 months
The MFJ-250, like the Heathkit Cantenna it is a copy of, is simply a common paint can filled with mineral oil and containing a 50 Ohm resistor cooled by the oil. It's impedance is relatively flat through 10M, just don't expect it to be a perfect match on higher bands. This dummy load can also reliably absorb 1 KW or so of CW for a minute or two without self-destructing. The main issue with the Cantenna style dummy loads is mineral oil vaprozation and recondensation on the top of the lid. Sealing the lid is not practical due to oil vapor pressure - even if you could seal the lid, vent hole and SO-239 connector, the can would soon deform from internal pressure, especially if used to absorb a lot of RF power, and potentially burst. And remember - the oil inside is FLAMMABLE. So, most old-time users knew enough to put the Cantenna dummy load in a galvanized bucket or small metal trash can, with a PL-259/SO-239 "barrel" extender on top to keep the coax from wicking up any of the seeping oil. Pretty much the cheapest 1KW dummy load possible. If you'd like an excellent dummy load/termination, forget the amateur dummy loads, which are all by and large junk, and find an old Bird 6736, 694 or similar. SWR flat as a board throughout the HF and 6M bands (and often higher, depending on model), and can handle 1 KW all day, 1.5 KW intermittant, no problem.
KF5VQY Rating: 4/5 Nov 6, 2017 16:34 Send this review to a friend
Works fine, seeps just a hint of oil thru lid rivets  Time owned: 6 to 12 months
Bought this thing 8 months ago, filled it with MFJ's oil, set it on a paper plate in a corner of the shack. The paper plate has stayed bone dry, so the can isn't leaking. I run a kilowatt through this thing every time I re-tune the amp (whenever I change band or freq, typically several times a night). Been working fine for me all along. I've even pumped several minutes of SSB at 1 KW into it at a stretch and it did get a little warm, but only a little. I have noticed the faintest hint of an oil film developing on top of the lid, so I'll probably wipe that off every few months or so. That and the fact that the lid is rather thin gauge metal is why I'm giving this product a rating of 4 overall.

I've had no problems with this unit, and I'm glad I have it in my shack. If I ever need another high power dummy load I'd buy another one of these again.
KI7AQJ Rating: 1/5 Nov 28, 2016 21:58 Send this review to a friend
The paint can is even a pile of steaming dung.   Time owned: 6 to 12 months
I bought one of these with visions of the old Heathkit Cantenna, but my gawd, where did they get those paint cans? Mine leaked oil all over the place! It got stuck outdoors with my Greenlee hydraulic punch driver box. The punch driver pump was resealed, but the box will piss oil for the next 50 years, and the MFJ can will piss oil for the next 100 years, so out they went. I found a lovely 1000 watt oil bath 52 Ohm load with a meter at a thrift store. It was made in 1962, and it looks brand new. The MFJ load looked like it went through two wars, and 4 days with the Samsonite gorilla porter. The leaking oily can mess was relegated to the trash, on hazmat collection day. I did yank the resistor and the connector & put those in a plastic bag, until I decide to install them into a real paint can, and not some poor excuse made from metal that is only slightly thicker than heavy duty Reynold's Freezer Foil. Charge an extra $5 and get some better canisters. Why in the blue blazes does MFJ pass this junk off on people? I'd gladly pay $20 or $30 more for a nicer can, with a $7 pressure relief disc soldered on it. The MJF stuff shows up with missing parts, missing screws, rivets that are crooked & loose. IT'S DEPLORABLE! How can anyone work for a company that cranks out such shoddy workmanship. I'd sooner clean chemical toilets with a toothbrush than partake in purveying junk on the level of some of these MFJ products.
K4TAX Rating: 2/5 Mar 25, 2016 13:40 Send this review to a friend
Leaks Oil  Time owned: 3 to 6 months
The SO-239 connector in the lid leaks oil terribly, and yes I only filled it up to the level they tell you in the instructions. Every time I disconnect the coax it is dripping with oil.

I disassembled the unit, sweat soldered the connector to the lid, then re-assembled and put it back together. Still leaks oil, which I find is being forced up through the connector.

While the load works as specified, it is a messy situation.

I do not remember this being a problem with the Heathkit load. They must have used some type of sealed connector, or maybe the connectors were better 50 years ago.

Oh well what is one to expect today for $75.00.
WB3CII Rating: 2/5 Aug 16, 2015 16:21 Send this review to a friend
Pretty sorry construction  Time owned: 0 to 3 months
I used to have a Heathkit Cantenna dummy load years ago so when I started working on radios again I thought this would be a reasonable replacement.

Well, I guess it does work but ......

The "can" must be the absolutely cheapest one available on the market :( It is so flimsy and flexible that it is a joke. The side of the can was dented in when I took it out of the sealed box, had to push it out.

The SO239 connector in the lid leaks oil terribly, and yes I only filled it up to the level they tell you in the instructions. Every time I disconnect the coax it s dripping with oil :(

I do not remember this being a problem with the Heathkit, they must have used some type of sealed connector.

Not sure if I am going to keep it or send it back. I might try to find a sturdier can and a sealed SO239 and just use the resistor and the oil.

Come on MFJ, you could have spent an extra $5 and had a decent product instead of one that perpetuates your poor reputation.
N4NYK Rating: 5/5 Feb 27, 2014 10:16 Send this review to a friend
Performs as advertised  Time owned: 6 to 12 months
This dummy load has performed as expected. I use it for all HF requirements (low and high power) before applying power to my complex conjugate matching network and non-resonant antenna. SWR is low across all HF frequencies. No oil leaks, seepage or problems. Purchased from R&L and they did a great shipping job as usual.
K4HYJ Rating: 5/5 Feb 4, 2013 09:00 Send this review to a friend
Works as advertised  Time owned: 0 to 3 months
I bought an AL-811H amp and needed to upgrade my dummy load. I bought the 250 on sale at HRO in Atlanta with the included transformer oil (has better heat dissipation than mineral oil).

I've been using it for almost 2 months with no problems. I did fill it closer to the top than I should have (I didn't read the instructions), and when it got hot, I had a little seepage around the SO-239 connector - my fault!

At 40 meters, it reads 51 ohms. At 10 meters, it reads 49 ohms. Same readings before and after 700watts applied. Straight forward product executed well at a reasonable price.

I thought about building my own, but the parts were more than what I paid for the 250 - not including my time.
VE3BDE Rating: 5/5 Feb 14, 2012 11:02 Send this review to a friend
A + FIVE STARS!!  Time owned: 0 to 3 months
NJ2H Rating: 0/5 Mar 20, 2011 07:32 Send this review to a friend
WARNING!  Time owned: more than 12 months
I bought this dummy load about two years ago complete with MFJ's transformer oil. It worked great.
But, I just picked it up to move it and found the can very light. The bottom of the can was coated with oil and the plywood under it was soaked. I opened up the can and there was a large amount of rust on the inside bottom and a pinhole where the oil was slowly leaking through. The resistor and everything else looked like new. It appears that the can bottom is not compatible with the oil and was corroded by it. This is potentially dangerous and I recommend that if you have this dummy load you open it up and look at the bottom.
N4RSS Rating: 5/5 Sep 2, 2010 14:18 Send this review to a friend
Takes a licking  Time owned: 0 to 3 months
Tested out the QRO-2500DX into it today. RTTY carriers of 1800 to over 2kw, some 2100w+ SSB and one 2400w whistle across different bands.

SWR seems stable after this beating but the can's hot as expected.

Impedance before: 48-52 depending on band, after: same, using antenna analyzer
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