I have a new one from MFJ that is really a reseller for another 
company.  It is RF protected up to 300 watts I believe.  A relay is 
used to take the unit out of the circuit.  I used it to tune my 
external tuner for minimum SWR.  I had to turn the RF gain way down 
to hear the change in noise.  The noise pulses, but it is hard to 
hear the change with the RF gain up and AGC turned on.  I haven't 
used it much, but it worked fine for me.

73,

Dave, W7OQ

  At 03:33 PM 8/9/2013, you wrote:
>Ok, thanks Howard, I appreciate your information.  Will have to
>check with HRO to see if they even make them now.  73, Jim WA6EKS
>
>  ----- Original Message -----
>From: Howard Kaufman <[log in to unmask]
>To: [log in to unmask]
>Date sent: Fri, 9 Aug 2013 17:29:33 -0500
>Subject: Re: Experience with Noise Bridges?
>
>I used an old noise bridge 30 years ago.   It was very accurate
>with a deep
>null at the resonant point.  You couldn't transmit through it and
>it had RCA
>jacks.  I imagine they are better now.