I had one of those years ago. Believe me, they do have an effect. when properly utilized, they can reduce or eliminate RF bites around the shack. 

btw, if you build a VCO using an XR-2206 function generator and calibrate it for no tone at zero point on the meter, you can get it to work really fast. I wish I still had my old one. btw, that same circuit can be used on any cross needle SWR bridge, only needing the extra one for the reflected reading. THat and a set of stereo headphones and you can  tune the antenna with a minimum of fuss. There is also an antenna noise bridge that you can use too. EIther method can work for the blind ham.

-eric

On Jul 17, 2015, at 11:21 AM, Lou Kolb wrote:

> Ron,
> 
> I have one in the shack but have always found it difficult to use without 
> sighted help. There is a meter on it that, as I recall, must be adjusted for 
> the maximum reading. I suppose if you had an audio oscilator across it it 
> could be done. The unit did seem to have some positive effect on a situation 
> where there was RF in the shack but I would think it's effectiveness would 
> vary greatly with the circumstances. 73. Lou WA3MIX
> Lou Kolb
> Voice-over Artist:
> Radio/TV Ads, Video narrations
> Messages On-hold:
> www.loukolb.com
> ----- Original Message ----- 
> From: "Dr. Ronald E. Milliman" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, July 17, 2015 2:09 PM
> Subject: MFJ-931 Artificial RF Ground
> 
> 
>> Have any of you used the MFJ-931 Artificial RF Ground? If so, what do you
>> think of it? How well did it work for you? Can a blind person, a person
>> without useable eyesight, adjust it easily and effectively?
>> 
>> 
>> 
>> Ron, K8HSY
>> 
>> 
>> 
>> 
>> 
>> Dr. Ronald E. Milliman
>> 
>> Retired Professor of Marketing