Here is a quote from one site:
Of interest is the 1:1 balun mounted at the input of the tuner (rather
than the output where it would be exposed to highly reactive loads).
The various components are floated above chassis ground. When properly
adjusted, the balun sees a 50 ohm load both at the input from the
transmitter and at the output. Its not a perfect replacement for the
link coupled circuits of yesteryear, but in my experience so far, it
perfoms significantly better than competing tuners employing 4:1
baluns. I've tried a few of these matching networks and not one of them
provided an output to tuned feeders even close to being balanced. The
AT4K-BAL is a leg up on this account.

There are dozens of other sites, but it is all the same info..including
several ARRL articles.
The issue is not lightning protection, as you suggested.
Thanks

On 14 Dec 2004 02:31:11 -0800, "
wrote:

Here is a quote from one site:
Of interest is the 1:1 balun mounted at the input of the tuner (rather
than the output where it would be exposed to highly reactive loads).
The various components are floated above chassis ground. When properly
adjusted, the balun sees a 50 ohm load both at the input from the
transmitter and at the output. Its not a perfect replacement for the
link coupled circuits of yesteryear, but in my experience so far, it
perfoms significantly better than competing tuners employing 4:1
baluns. I've tried a few of these matching networks and not one of them
provided an output to tuned feeders even close to being balanced. The
AT4K-BAL is a leg up on this account.

There are dozens of other sites, but it is all the same info..including
several ARRL articles.
The issue is not lightning protection, as you suggested.
Thanks

The few balanced tuners that are being manufactured nowadays all seem
to employ the balun on the input side. To use the words from MFJ's ad
copy for their balanced tuners:

"A 1:1 current balun is placed on the low impedance 50 input side to
convert the balanced T-Network to unbalanced operation. The balun is
made of 50 ferrite beads on RG-303 Teflonâ„¢ coax to give exceptional
and efficient isolation. It stays cool even at maximum power."

Basically, the balun hooks the balanced tuner to the unbalanced output
of the transceiver.

In years past, there have been heated discussions in this group as to
whether the balun belongs on the input or output -- you could do a
Google search if you're interested.

Bob
k5qwg