Hi,
Vectronics calls there noise bridge a tuning aid. Vectronics is an MFJ company and a radio dealer will probably have a lower price than is given on the link listed below.
One more advantage of this noise bridge is that the bridge is preset to 50 ohms and that's the load your transmitter is looking for.
http://www.vectronics.com/Product.php?productid=VEC-512
Bob, K8lr, [log in to unmask]