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Reviews For: MFJ-901B

Category: Antenna Tuners/Matching Networks

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Review Summary For : MFJ-901B
Reviews: 53MSRP: 79.95
Description:
MFJ'S smallest 200W tuner
Product is in production
More Info: http://www.mfjenterprises.com/products.php?prodid=MFJ-901B
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
15534.2
GW4JPC Rating: 2006-10-14
Tunes awide range of loads. Time Owned: 0 to 3 months.
I bought the MFJ901B recently via eBay to use with my Index Laboratories QRP rig for portable work.It is just the right size for the QRP rig,matching its' foot print exactly.The tuner seemed to tune anything via the co-ax and wire antenna terminals,but it refused to tune any balanced feeder.I opened it up to see what was going on.MFJ's famous quality control,or lack of it,had been going on!
The two wires on the tuner side of the balun were both soldered to the ground terminal.A couple of minutes work with a soldering iron to attach one of the wires to the tuner output, hey presto,a really useful little tuner. Works a treat with my portable 66 foot dipole fed with 300 ohm ribbon.
All in all a good ATU, but watch out for the lack of QA from MFJ.
VE3XDB Rating: 2006-08-09
Works as intended Time Owned: 3 to 6 months.
Have been using this tuner for several months with my Kenwood TS-440S, first into a half-size G5RV and now into an OCF dipole. Opened it up to do a visual inspection, and all seemed fine, except the knobs on the variable caps were installed 180 degrees out of phase from what it says in the manual. Overall quality is fine, and I have been pleasantly surprised by the quality of the inductor switch. Seems to handle changes to the switch settings with RF applied up to 20 watts. (Never tried it at higher power levels.)

This is a simle T circuit, written up in most every antenna book. The values of both the inductor taps and the variable caps seem about right. Tunes everything that I have tried effectively.

It does need a bypass switch, which can be easily installed. Took me about 30 minutes to complete the task. Remember that a T network is a high pass filter, so if you also use your rig as a shortwave receiver or as an AM broadcast receiver, the tuner will need to be bypassed, or you won't hear anything! (Believe me, I tried it!)

I am satisfied with this product.

Best regards,

Doug VE3XDB
M0DCD Rating: 2006-04-07
Does the job Time Owned: more than 12 months.
I have had one of these for a long time, originally to tune my QRP rig (about the same size) which it does well.
Going up to QRO (100W) with a Windom did hit a few snags on 160m but it could match better than the auto ATU in my TS440SAT.
I did find an unsoldered joint when I noticed it was microphonic, but otherwise it's taken a lot of misuse. Tatty it may be now but it still works.
Would I buy another? No, I'd go for one with a roller coaster just to squeeze the tuning in a bit bit tighter.
F4DYT Rating: 2006-02-23
Old version made in Sweden Time Owned: 6 to 12 months.
I bought an old, second hand 901B from a radio-club who sold equipment. It was built in Sweden and is an old version. Once opened shows decent quality and finition. I liked the fact that it has an air core, which explains its size. Solderings seem to be done by skilled hands. No cold solders.

It works correctly, but of course is intended to catch only *moderate* SWRs.

I give it a 4 and not a 5 because it lacks a bypass switch.

Beginners please remember to disconnect your AGC while searching for maximum noise in the receiver.

73 Dimitri F4DYT
VA3EAM Rating: 2005-11-07
Great little tuner! Time Owned: 6 to 12 months.
I bought this little tuner used at a hamfest and it works great. If you need a small and simple tuner and already have a meter, then this is the tuner for you. I have been using a 55 foot wire and it tunes up 80m to 10m. Used it with a G5RV and a 40m homemade dipole that tuned up on perfect on both 40m and 20m.
KA2JIZ Rating: 2005-10-02
Good portable tuner Time Owned: 0 to 3 months.
Been using this little fellow a couple of months now without any problems. Gave it the shake test when it arrived and nothing, shook, rattled, or rolled inside the black box. However, note that it is used with rigs having 20 watts maximum output power. Good tuner to travel with accompanying a low power transceiver.
MW3KHD Rating: 2005-07-26
A bit fiddly ... needs bypass switch Time Owned: 0 to 3 months.
First off it works on my open loop which is cut to 1/4 wavelength on 80m. Matches that to 80m and all higher frequency bands. No match on top band. The documentation says that the tuner requires at least 1/4 wavelength for long-wires, open-loops, and the like.

Tuning is a bit fiddly. The knobs are small and the settings can, on some bands, be critical. This is only to be expected from such a small device and I got used to it after a while.

One thing that is missing is a switch to bybass the tuner for operations outside of the MF/HF bands (e.g. listening to LW/MW broadcasts), when using an antenna cut for a specific band, or when you just can't be bothered to tune when listening to strong broadcast stations on HF (e.g. BBC). It proved easy enough to add one. The case is aluminium and easy to work, there is space enough for a big switch next to the Tx input, and quite a bit of room inside the case to get the iron in. I think MFJ should have one on this device as standard.

Looking inside ... there were none of the MFJ quality control problems reported by others. The exterior finish is not great and I noticed (just in time while degreasing) that the paint used for dial markings rubs off easily with all but the slightest pressure of a rag damp with alcohol (I was using meths).

I can't comment on the power handling as I have a 10w restriction on my license but the capacitors look a bit small for the 200w that MFJ claim for the device. The documentation mentions possible arcing problems at 200w on top band. At QRP, I have experienced no problems.

On the whole, I am happy with the purchase. It has a "cheap and nasty" feel but it is cheap and it works.
G7UJY Rating: 2005-07-24
Simple, well made. Time Owned: more than 12 months.
I ordered mine before reading any reviews. I opened it when it arrived expecting to see any one or more of the problems other reviewers on this site had experienced. However the construction was fine, curiously the capacitor knobs where 180 degrees out, min was max. I set them up correctly as did a previous reviewer. I wonder if it was the same person that made them? It works fine matches kites, slinkys, long wires etc.
M3SKF Rating: 2005-02-23
GOOD KIT Time Owned: 0 to 3 months.
Tuner seems to work as described, very simple to work very compact in size great for base or mobile work.Quallity is not the best in any mfj gear this kit is no exception to that rule the finish is not that great yet inside the unit all solder joints are intact & of good standard.So far pleased with the tuner as i said it works fine.
VK5SN Rating: 2005-01-28
Fab tuner Time Owned: more than 12 months.
I got this as a gift from a ham friend who no longer needed it. As everyone says, for the price it is great tuner. I like its simplicity! I have tuned coax fed antennas, random wires and balanced fed antennas - never faced a problem!