Jim,

The MFJ-202B is not the same animal as the MFJ-212.

The 202B MFJ RX Noise Bridge

Quickly adjust almost any antenna for maximum performance, 1 to 100 MHz.

Lengthen or shorten your antenna for minimum SWR. Measure resonant 
frequency, feedpoint resistance and reactance.

Works with any receiver or transceiver.

Hand-calibrated resistance scale, expanded capacitance range and exclusive 
built-in range extender.

The MFJ 212 MatchMaker for Tuner
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. MFJs RF*Guard bypasses the MFJ-212 to prevent damage. Handles up 
to 300 Watts. Works with all radios 160-6 Meters.

The 202B device is for adjusting antennas and the 212 is for adjusting your 
antenna tuner.

73

Howard #3

----- Original Message ----- 
From: "Jim Gammon" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 03, 2013 12:38 PM
Subject: Re: MFJ Noise Bridge: Another Question


> How is the MFJ 212 different than the MFJ 202? I have one of the
> latter and there's no charger jack.  It only runs off the
> internal 9 VDC battery.  I hooked it up once to my receiver and
> tuned for a null but have no idea what kind of readings the knobs
> on the front may be giving me.  I assume there must be some
> numbers that correspond with the antenna resonance point or
> something.  Jim WA6EKS
>
> ----- Original Message -----
> From: "Howard, W A 9 Y B W" <[log in to unmask]
> To: [log in to unmask]
> Date sent: Tue, 3 Sep 2013 11:17:32 -0500
> Subject: Re: MFJ Noise Bridge: Another Question
>
> Tom,
>
> I measured the polarity of the MFJ suggested wall wart that will
> work with
> the Noise Bridge and the center of the DC plug is positive as Pat
> indicated.
>
> 73
>
> Howard #3
>
> ----- Original Message -----
> From: "Tom Behler" <[log in to unmask]
> To: <[log in to unmask]
> Sent: Tuesday, September 03, 2013 8:34 AM
> Subject: MFJ Noise Bridge: Another Question
>
>
> Hi, all.
>
> I have another question about the MFJ Noise Bridge we have been
> discussing.
>
> I checked the MFJ web site, and found the MFJ 212 listed at a
> cost of $99,
> which is what I expected.
>
> They indicate that the device can be run either via a direct DC
> connection,
> or a wallwart power supply, which costs another $14.
>
> Rather than spending the $14 on the extra wallwart, I'd rather
> run the
> unit
> off my rig runner via an Anderson Power Pole connection.
>
> However, I'm not sure how the plug for the DC connection should
> be wired.
> For example, is the tip positive?
>
> In general, I'd be interested in how others on the list who have
> the noise
> bridge power the unit.
>
> Tom Behler: KB8TYJ