Cecil Moore wrote in message ...
ON5MJ wrote:
You can fibd the schematic (all the manual) on MFJ in PDF format.

Thanks, I should have noticed that. I don't see why this design
balances currents any better than an unbalanced tuner with a
balun on the output. Common mode currents flow straight through
the balanced part of the tuner until they encounter the unbalanced
choke-balun. If the two balanced currents were sampled and metered
and the capacitor tunings were all independent, then the currents
could stand a chance of being manually balanced.

Cecil,

Could you elaborate a little on this? I am really
not very knowledgeable on this subject. I thought that by having the
the balun on the input rather than the output you eliminated the
possibility of operating the balun beyond its design parameters.
I was told that by not having the balun look directly into
the antenna you avoided having it see drastic changes in
impedance that it was not capable of handling. Presumably this
condition does not exist as much with the balun looking directly
into the tuner as the impedance is not capable of changing beyond
the balun's design parameters. Again, let me know the validity
of this theory as I am not an expert in this field.

I gather that by having the four capacitors ganged in groups
two the chances of having the currents in each leg balanced are
eliminated. Also the lack of being able to meter the current in each
leg diminishes the chances of a totally balanced output.

So the question is how is the 974H better than my old MFJ
949E? I must say that at this stage,I can see no difference,
but I probably do not know enough to know how much I don't
know!(as we used to say in Nebraska).

Another question is why is a link tuner better in this situation?
(Tuning a balanced feedline antenna?)As I know of no link tuners
that are currently in production,what would you reccomend in this
situation?

Kent Tunks KC6LXR