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Reviews Categories | Antenna Tuners | MFJ-902 Help


Reviews Summary for MFJ-902
MFJ-902 Reviews: 30 Average rating: 4.4/5 MSRP: $69.95
Description: Mini Travel Tuner
80-10 meters
150 watts
Product is in production.
More info: http://
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G4KSG Rating: 4/5 Aug 10, 2015 02:58 Send this review to a friend
An OK tuner  Time owned: 0 to 3 months
This is not an all can do tuner - its very compact and very basic. It didn't work right- first-time.

I recently bought one of these old version tuners. Before using I checked the cap’s were rotating freely – they were not. I took the cover off and made some adjustments to the vanes and did a proper (continuity) test with my DVM – problems fixed. Put the cover back on and put it in circuit and it was obvious all was still not well. Took the cover off re-tested and it was OK.
I put the cover back on and fitted each fixing screw one at a time. The last one caused the problem. The holes for that screw were not in line and as it was fitted/tightened it caused the chassis to distort and therefore put a force through the short stiff wire from the 239 socket to the fixed vanes sufficient to move them.

There were two solutions for this – replace that solid wire (and its mate) with flexible wire or enlarge the holes on the cover. I enlarged the holes with my taper reamer hand-tool. Hey presto – now works a treat.

BTW I noticed that (and its not unusual) the gaps between the rotating and fixed vanes were not 50/50 resulting in a reduced voltage rating so beware. I think perfect 50/50 variable cap's will cost more - and that's not a feature of MFJ's business model. Despite this product costing a lot for what it is.
 
HA7WX Rating: 5/5 Sep 17, 2014 02:53 Send this review to a friend
Great little tuner !  Time owned: more than 12 months
I am now reviewing the device, not its price (it's pricey for what it is, especially in Europe).
The price of 50 to 80 USD (used or new) would be spot on IMHO.
So i have had this one since 2007 and used it randomly. Almost as needed at a HAM radio station as an antenna analyzer can be (or a dummy load).
Every time i used it i could get a match at 50W pep (be aware and realistic this one will handle the half of the claimed power, or let's say a normal rig at 80-90W SSB peeks).
Also, it might depend on your conditions and you may require a balun to help match the impedance.
This little box even gives me a match at 6m band.
Not especially necessary to trade the old one to get the newer one with 6m capability, it sure depends what PWR and what antennae you want to match on that band.
Overall happy with and this one won't fail on you once you use it within its capabilities.
I did my homework: when i got it new, i reviewed it inside to check for bad solder joints and to check the capacitors plates not touching.
I recommend it to anyone into portable, mobile or on a budget at home.
Good job MFJ! 73s de Chris HA7WX
 
KU4UV Rating: 4/5 Jun 26, 2013 10:55 Send this review to a friend
A good tuner, but here is how to make it a great tuner.  Time owned: more than 12 months
I started using the MFJ-902 antenna tuners almost 10 years ago. I have bought and sold about 3 of these particular tuners over that time period, for various reasons. At one time I purchased two of the tuners, one for the shack, and one for the mobile. I am currently operating only QRP until I can decide on what type of 100-Watt radio I want to purchase, hopefully in the next few months. While I continue to think that the 902 is a good tuner, if you purchase one that has problems, there are some simple ways to fix the tuner to make it last and work for many years to come.
My twin brother and I operated Field Day last weekend from one of our family farms here in Kentucky. We used my brother's Kenwood TS-440, along with a ladder-line fed dipole up about 60 feet. The tuner was able to tune the diple on the bands that we operated on during the Saturday of Field Day without any real problems. We went to bed in the tent early on Sunday morning. When I woke up on Sunday morning and tried to operate, I found that the tuner wouldn't tune the antenna on any band, not matter what I tried. After trying several different things, we finally settled on just using a longwire antenna and using the TS-440's internal antenna tuner. The internal tuner was able to match the longwire on almost every band, except 10 meters.
When I got back home and connected the MFJ-902 to my 20 meter QRP transceiver, I still found that I could not get the tuner to match my outside antenna. I eventually discovered that I had a bad connection somewhere in the tuner. Having replaced the SO-239 connectors in a prior 902 that I owned, I decided to do the same on this particular tuner. I ordered a couple of Amphenol SO-239 connectors from Mouser Electronics, as well as a new DPDT selector switch for the back of the tuner. The SO-239 connectors that MFJ uses honestly aren't that great, and it seems one of them was the culprit. I don't know what brand of connector MFJ uses, but the connectors on the 902 just look like cheap junk. I choose to go with Amphenol military-grade SO-239 connectors when replacing them on ham gear, and have never had a problem. If you own this tuner and are having problems, do yourself a favor and replace the junk connectors MFJ uses with the Amphenol connectors (I use Mouser P/N#523-83-798). The connector are about $5 a piece, but well worth it, as they are about the best SO-239 connectors on the market. Since I knew I was also going to have to take the selector switch off to replace the SO-239's, I decided to replace the switch as well. (I use Mouser#112-R13-602B). I plan on posting a video soon on Youtube showing the mods I performed on the 902 to make it a much better tuner. Just enter "KU4UV" for my videos.
So bottom line, the 902 is a good tuner, that can be turned into a GREAT tuner by performing a few simple mods.
 
GM0WNR Rating: 5/5 Apr 1, 2012 12:55 Send this review to a friend
Great compact tuner  Time owned: 0 to 3 months
I use this for tuning my 70 foot long doublet. This little marvel can tune my antenna from 40M to 6M at 100 Watts with no arcing so far. It is a great small size and fits in my small shack quite nicely. I am looking forward to working from the garden or / portable with it this summer with my QRP rig. The absence of an SWR meter is no hinderence to me and cannot speak highly enough of this little gem!
 
K5ACO Rating: 5/5 May 22, 2011 09:47 Send this review to a friend
Great QRP Tuner  Time owned: 0 to 3 months
A nice, tiny, tuner that has real capacitors. Good for home or travel use. Probably OK at 100w to "flatten" the SWR on a resonant antenna. A good buy used for $50 or so if you can find one. Cap plate spacing is close, open it up and verify none are bent (easy to fix)
 
KK9H Rating: 5/5 Mar 1, 2011 08:30 Send this review to a friend
Nice little tuner  Time owned: 0 to 3 months
I bought one of these to have available for when I operate portable on vacation or at Field Day. The interior construction is first rate, but I did decide to rewire it to bypass the "Bypass" switch in order to increase its efficiency a bit. I plan to either have the tuner in line or not at all. One of the first things I did was try it on my various antennas and it tuned up easily and quickly on all bands that it covers. One of them is a 130 ft. inverted L that I use on 80, 40 and 30 meters and it tuned up on each of those bands without issue. I can tell that the MFJ-902 will be ideal for portable operation.
 
KF6NTE Rating: 5/5 Dec 17, 2010 12:02 Send this review to a friend
Good performer  Time owned: 0 to 3 months
I find manual tuners give you complete control
of the SWR your radio driver sees.
Have had this for several days now and have been able to tune and operate my G5RV on 20,40 and 80m without a problem on QRP power. This tuner is a definite keeper for this kind of operation. I like its compact size and simplicity. I look forward to traveling with it in the future.knock on wood, so far all the MFJ gear I have has performed very well. No issues.
 
N4RSS Rating: 4/5 Aug 19, 2009 15:14 Send this review to a friend
Tunes EFHWA  Time owned: more than 12 months
So far it tunes a EFHWA on 20, and seems to have no problems with QRP power.

I'll test on 40 and report back but expect no problems.

I may not need that Par End Fedz after all.
 
N2UGB Rating: 5/5 Sep 4, 2008 08:41 Send this review to a friend
My FB QRP Tuner  Time owned: 0 to 3 months
I've had it a few weeks, so this is not a long-use report. I can say that, right now, it works well with my Buddistick antenna and FT-817ND transceiver with in-line OHR QRP wattmeter.

Not wishing to witness any sloppy work, I didn't open it up. But I did give it the MFJ-Product-Shake. Nothing heard. All controls move smoothly, no scraping sounds or sensations.

It is able to fine tune my Buddistick which, because of placement of antenna and counterpoises, cannot be as well tuned as it should be.

I wouldn't think of putting more than QRP output to it. When a tuner is rated for 150 watts and not the usual 200, I become cautious.

Size and weight-wise, it is a good atu for portable ops. But I wouldn't bang it around in the process of getting it to a choosen spot. As I am not into that, it is not an issue.

So my short-term opinion of the 902 is a very good QRP tuner for those who use an outboard QRP SWR meter for accurate readings or the one in the FT-817 for good ballpark readings.
 
IZ1CLB Rating: 4/5 Dec 9, 2007 08:42 Send this review to a friend
Good  Time owned: 0 to 3 months
Not a bad device; work very well in portable operation with a long 8 or 12m vertical fiberglass fishing rod (connected only at central point of antenna connector) and 4 or more radials, fast and easy tune with FT817 internal swr-meter. Good for any qrp portable operation (5w only, not 100w!)
I recommend, before use, a quick checkup of two variable capacitor, see carefully spacing (and if necessary correct). Very small and light into rucksack.
 
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