well,
the noise antenna can be anything from a short rod type to a long wire. I use an antenna tuner on that side just to tune a 20 foot run of wire to resonance. Combine that with another tuner on the main antenna, and you will have 2 optimal antennas for the device. one of the items in the manual states that the antenna noise canceller may not work very well in mismatched settings. the closer to resonance you can get both antennas, the better it works.

DE n7zzt Eric

On Oct 15, 2015, at 3:31 PM, Mike Keithley wrote:

> I'm wondering what the noise antenna would be like. My shack is in a mobile home, and there is a 25-foot run of coax to an autotuner feeding a long wire.
> 
> ----- Original Message -----
> From: Eric Oyen  <[log in to unmask]>
> To: [log in to unmask]
> Date: Thursday, October 15, 2015 3:01 pm
> Subject: Re: MFJ-1025 noise canceler
> 
>> 
>> 
>> its fairly effective against single phased sources (like powerline buzz =
>> and other stationary noise sources). It is the unamplified version and =
>> does introduce a little signal loss. However, for what it is, it works =
>> good enough that I can do weak signal work on 80m.
>> 
>> Now,as for what it is:
>> the mfj antenna noise cancellation device is basically a diversity =
>> antenna matrix. It takes signals from both the primary antenna and a =
>> secondary (noise) antenna. It then mixes (or phases) those inputs such =
>> that (when properly adjusted) the noise disappears while leaving the =
>> signals you want intact. This technology predates DSP technology and is =
>> still very useful. In fact, in combination with DSP technology, noise =
>> can almost entirely be eliminated.
>> 
>> DE n7zzt Eric
>> 
>> On Oct 15, 2015, at 2:01 PM, Mike Keithley wrote:
>> 
>>> How effective is the MFJ-1025 noise canceler? What is it?
>>> =20
>>> Thanks.