There are a number of similiar circuits, but I can't think
of any others being produced commercially at the moment.
The BMG SuperDF is not longer available, but ther is a
lot of good information still on the website at:
http://members.aol.com/BmgEngInc/The new Little L'Per from L-Tronics is now available, and
should be an excellent unit, but not exactly inexpensive.
http://www.ltronics.com/You might contact Bryan Ackerly VK3YNG and see if he can
provide a 155 MHz version of his UltraSniffer: this is
very easy to use, though you have to provide an appropriate
antenna.
http://users.bigpond.net.au/vk3yng/foxhunt/foxhunt.htmlYou'll find lots of links to DF information and sources
at K0OV's HomingIn site:
http://members.aol.com/HomingInAlso, you might want to start a new thread on this topic,
as I see that this one has now slipped onto the second
page.