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Reviews Categories | Antenna Tuners | MFJ-212 Help

Reviews Summary for MFJ-212
MFJ-212 Reviews: 7 Average rating: 5.0/5 MSRP: $79.95
Description: MFJ-212 Tunes up your antenna tuner without transmitting a single milliwatt! No power. Precisely tune your antenna tuner for a 1:1 SWR -- no additional "tweaking" needed. Avoids overheating/arcing caused by high SWR and long tune-ups. MFJ's RF*Guard bypasses the MFJ-212 to prevent damage. Handles up to 300 Watts. Works with all radios 160-6 Meters. 3 1/3 x 1 1/4 x 4 in. 9-12 VDC or 110 VAC with MFJ-1312D, $14.95
Product is in production.
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K8NDS Rating: 5/5 Jan 16, 2014 14:36 Send this review to a friend
A must for Magnetic loops  Time owned: 6 to 12 months
I use Helical magnetic loops for all my antennas.
This device is a must especially if you have a pan adapter. I use the MFJ-212 in conjunction with my LP pan2, wide screen pan adapter. This device gives me a perfect display of the High-Q resonance point of my HL Magnetic loops. You can watch the dip move across the screen in real time to quickly move from one frequency to another with precision for a 1.0/1 match. Check out the video depicting this operation.
KF4CQR Rating: 5/5 Sep 24, 2011 14:21 Send this review to a friend
Good Device  Time owned: more than 12 months
1. Works as advertised. Good piece of equipment for tuning up without a carrier and bothering your fellow hams.
2. Caveats:
a. Draws a little over 100 milli-amps – will kill a 9v battery in a relatively short time… just a few tune-ups into an antenna you have no idea where the initial antenna tuner settings should be and you have a dead 9v battery (I was not using an Alkaline 9v… just a cheap one).
b. Null is sharp. Unless you know the general settings of your tuner before staring the tuning process, be prepared to make small adjustments in your tuner’s parameters when tuning into an unknown source (random wire antenna for example).
3. I bought this product about one year ago. Original intent for the purchase was to tune a QRP rig in a field environment. Be prepared to make small adjustments on your antenna tuner as the nulls are rather sharp and you can miss the “sweet spot” if you are not careful. An analog SWR meter gives you an indication your antenna tuner settings may be “getting there” before your ear can detect a change in the background noise. Keep that in mind when deciding on what to use.
4. The built-in by pass relay and RF detection circuitry have saved my butt on several occasions when I accidentally keyed 100 watts PEP into the system while the device was on. The MFJ-212 safely by-passed the RF and was not damaged.
5. You would have a hard time trying to homebrew this device yourself for less money unless you had a junk box from heaven available to you.
6. General Antenna tuner comment: To this very day, I do not understand why people disparage the use of an antenna tuner, especially when dealing with a resonant antenna. These Hams are limiting themselves to a narrow range of frequencies (especially on 80 meters). Using an inexpensive tuner will allow you to easily work the entire 75-80 meter band on a simple wire dipole with basically no noticeable loss in signal strength from increased SWR on a coax feed line. Get/make a tuner and enjoy increased frequency flexibility.

N2EIK Rating: 5/5 Jan 21, 2009 02:33 Send this review to a friend
Great!  Time owned: 0 to 3 months
I found that in order to use this device I need to turn my RF gain down to 50% and turn my pre-amp off. The 212 work like a charm every time, 1:1.
I wish I could have found one used, cheaper but I couldnt and bought new at $100... but overall money well spent and I can see why I couldnt find one used for months, I know I wont part with it! Closest thing to an auto-tuner!
Rig- Kwd TS-B200, Tuner, ATR-30
KJ4CNN Rating: 5/5 Sep 28, 2008 17:59 Send this review to a friend
Super Device for ham shack  Time owned: 0 to 3 months
This little box has been the difference between getting on line and not. With an end-fed, long wire antenna strung through a dense crop of trees (not the best type of an antenna area) I couldn't get my SWR down enough to reach out. Also with an older tube transceiver (Yaesu FT-101EX) I just did not want to burn out my final tube with extended tuning. Now, however, I just turn this box on, twist a few dials until the tone goes away and I am set to go.
The first day that I used it I worked 80m all night; almost was too tired to go to work the next day. Super product!
KM5TC Rating: 5/5 Dec 22, 2007 06:54 Send this review to a friend
Neat device  Time owned: more than 12 months
Bought the MFJ 212 from a fellow ham.
This works with my Icom 718 and MFJ 949E tuner.
Set your radio to desired band/freq, turn the
212 on and it emitts a pulsing noise,
set your inductor switch, turn trans/ant knobs
until you hear a null in the pulsing noise and
you have 1:1 or 1:2 swr readings on the tuner
and you're ready to. 73's
AB2TC Rating: 5/5 May 16, 2006 11:27 Send this review to a friend
A must have for anybody using an antenna tuner  Time owned: 3 to 6 months
Three months later I am still thrilled by it. I take back the last sentence in my previous review; no touch-up is required. I swear to you, except to characterize new or modified antennas (the initial null can sometimes be tricky to locate with the MFJ212), I have not put a tuning carrier on the band for the past two months. For amplifier folks, put the MFJ212 between the transceiver and amp, tune the tuner in receive mode, then tune the amp into a dummy load and you should be all set to go.
AB2TC Rating: 5/5 Feb 16, 2006 12:09 Send this review to a friend
A must have for anybody using an antenna tuner  Time owned: 0 to 3 months
This device sits between your transmitter/transceiver and the antenna tuner/SWR meter. When turned on, it injects white noise through a directional coupler towards the tuner. Any refleced power is heard in the receiver as pulsating white noise. Adjust the tuner for minimum noise and voila the antenna is tuned without transmitting anything but a few femtowatts of noise which can be heard by nobody. In reality, if you want 1.0:1 SWR, a quick touch-up might be necessary using a carrier (just a low power one, right?.

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