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mfj 949c

P

parallax

Member
Nov 4, 2010
17
0
11
Oregun
help....
my mfj 949c is acting weird.
when i key up.. the swr side needle can swing negative(below 0 swr).. whats going on?. upon testing with another meter, when it swings negative, its actually an increasing swr. i can adjust it to go on the positive side of the swr reading with the reostats.zero swr, seems to still be true zero.. but something is not right.
 

Hey dude welcome to MFJ and the J can mean junkkkkk.
I have two of these tuners and used one for 8 or ten years then it went bonkers. MFJ has terrible quality control and I have found cold solder joints on several pieces of their stuff over the years. That's what was wrong my tuner and after I resoldered the connection on one of the coils It worked fine again.
If you are lucky enough to get MFJ stuff that was assembled by a good solderer person:headbang You will not have much or any problems THAT'S IF.

Otherwise this has been a great tuner and I recommend them to anyone who needs a good tuner. I don't like the autotuners.......:thumbdown:

If you check yours with a magnyfing glass closely, you can probably spot a odd looking solder joint and if you reheat it you will probably fix your problem.
Good luck
\
PS I have several other MFJ products that work fine but just be warned that there may be a problem any time with them.:censored:
 
MFJ used to have a really bad reputation for bad quality control but in the last five years or so the quality has GREATLY improved. Like any manufacturer, some things will slip through but I believe the issue is pretty much a non-issue with MFJ now considering the number of products they sell. The reported instances of poor/nonexistant solder connections or loose/missing screws is very much less now than in years gone by.
 
I own 4 MFJ tuners now 2 - MFJ 962D, 1 MFJ 989C, 1 - MFL 941E and just bought an auto tuner that should arrive this week sometime Im guessing. I have had no problems with any of mine at all and would suggest them to anyone who would mention them. As mentioned I know a few years back there were alot of nightmare products floating around or circulating but again its way better now.

I laugh when people say MFJ!!! that stands for More Fu@!king Junk well gee thats funny considering all my MFJ products work great without issue!!?? When you misstuine a tuner under a high amount of power and arc it inside you a person has no leg to stand on when claiming its because it was a junk product.

With any manufacture and equipment theres always a misshapp or non perfect product that can and will slip through they test these for fuctionality not driving them to maximum capacity while spinning the tuning controls wildy to make sure that when Joe Bob buys his first tuner its a 1.5 KW MFJ and he downs a case of beer then tries out the tuner to learn how it operates while driving it with the 5 KW amplifier he bought from Bobby Rae with the families tax return this past year so when he arcs it and smokes the tuner he says DANG WHAT IN DA WORLD HAPPEN DARE FOR PETE SAKE i cant figure it out that tuner mfj makes must be junk!!

Theres always something that can eventually happen and I can say that there are other brands like Palstar that can survive more oopsy mistakes and are tougher in that aspect but they are also 2 to 3 times the money aswell.
 
The thing to remember is that a tuner is NOT a 'cure-all' by any means. They do certainly allow a lot of 'skootch' in using a particular antenna where it wasn't designed to be used. Soemthing else to remember is that with tuners, bigger is almost always better. Everything has limits though, so keeping things at least 'close' to being used for what it was designed for is a good idea. A 'good' tuner is going to be big, there's no way around that. That deals with the voltage/current levels that have to be dealt with in impedance transformations, not necessarily the amount of power put through it (power is still an important consideration, it just makes those voltages/currents being dealt with bigger too). The limiting factor with tuners and antennas is the feed line used to connect everything. Coax isn't always the best choice...
- 'Doc
 
I get screwed up with the specs of how they rated the older tuners with input?? Can someone explain this please Ive heard this brought up on 75 meters and they lose me. For example when they said rated at 1.5 KW the tuner is actually good for 800-900 watts?? What is the basis or theory for the (input) 1.5 KW rating.
 
Most tuners (until very recently) were power rated in Pep, not RMS watts. So, a 1000 watt tuner would be good for something like maybe 500 watts CW, but 1000 SSB. I remember reading where MFJ has 'revised' their power rating methods. I still tend to think of a tuner's rating as being in Pep, it's just a safe/fudge factor thingy. That power rating is also for a best circumstance type thing, not 'average' or worse type circumstance. No matter how 'they' do it now, being conservative is just good sense. Just because it -can- certainly doesn't mean that it -will-.
- 'Doc


Unless it specifically says differently, figure the watts rating is in Pep.
 
Thats how I was looking at it aswell being peak power. I have 3 bigger units I use with amplifiers MFJ-962D that says 1.5 KW and a MFJ-989C that says 3.0 KW along with 3 different model 300 watt models MFJ-941E MFJ-993 and an MFJ-948 and figured these were P.E.P. specs
 

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