Hi Tom and All, here's the essence of a friend's last summer's posts to me
re
this little noise bridge kit, still in production, from tentec.  Hope it may
help someone, DD

"There's a noise bridge board kit on the Ten-Tec site:

http://radio.tentec.com/kits/Accessory

This is the description:

""Have you ever wondered what good one of those
"R X Noise Bridges" could do for YOUR station setup?
Are you baffled by your antenna tuner or "transmatch"?

The 1051 is easy to build and super-easy to use. No
"R-X" controls, calibration or calculations needed.
Just connect it between your rig and antenna tuner,
set receiver to desired operating frequency, and
adjust the antenna tuner until the distinctive
modulated pulses (NOT just straight "noise"!) drop
to an easily-recognized "null" indicating that the
tuner offers a 50-ohm match to your transceiver
with NO on-the-air nervous experimenting with the
tuner controls!""

-----

This is a board kit only and costs $19
plus shipping.  From the size of the one 14-pin DIP
chip I'd say the board is probably about 2.5" x 3.5"
or so.  It would need to be mounted in some sort
of enclosure, _And _Remember! Transmitting into receive noise bridges
will destroy them, so unless Ten-Tec built in some
sort of transmit bypass, we'll have to have some sort
of T/R arrangement that cuts out the bridge when you
transmit.  I've emailed Ten-Tec asking them about
that..................Ten-Tec got back to me.  The board kit antenna
bridge runs on anything from 9-12V at very low
current.
It does not have any transmit bypass capability so
that has to be added.  A rotary switch could be rigged
to do that.  Since the bridge produces a beeping
on its own, that could be used as a reminder to
switch it out BEFORE you transmit.  This means that once you are tuned, you
*must*
remember each time to switch out the bridge before
you transmit, or you'll fry it......"""