[Elecraft] Tuner efficiency question

[Don]

>I haven't had lots of different tuners to compare myself, but I do have
> a Johnson KW Matchbox tuner.  It does a great job on Balanced lines.  I 
> didn't really know about the Palastar but just checked it out on the 
> website.  Looked like an interesting tuner.  But to me the downside of it 
> was that there is a balun on the output, which of course as Don stated is 
> a dominating factor in losses in a tuner (at least maybe that is what I 
> took away from his comments as well as other discussions on this subject 
> in the past).  Is there a modern tuner out there for balanced lines that 
> doesn't use a balun?

I don't know of any.  There is nothing wrong with using a balun as long as 
the balun is looking into a relatively low SWR .  The  baluns we are all 
familiar with only work well when feeding a balanced load that is fairly 
flat.   In other words the balun ought to be at the INPUT of the tuner 
instead of the OUTPUT.  This makes the tuner electrically and mechanically 
much more complex and expensive and that is why you don't see it done very 
often.  As John said .. half a db or so does not matter as far as signal 
strength at the receiving station  is concerned.  The only problem is that 
the power dissipation could damage the tuner or balun itself at the 
transmitting station.

As a purist with lots of time on my hands I am trying for the best of all 
worlds by building a true balanced L-C-L tuner with a balun at the input. 
It is an auto tuner with all of the bells and whistles and will (probably .. 
I think) handle up to 500 watts into my big wire antenna (but probably not 
into shorter antennas).  I am going to put it into a K2 case with matching 
button switches and a similar LCD.  It is working now on the benchtop at low 
power levels but it remains to be seen if, when packed tightly into a small 
case, I can keep the PIC controller circuits sufficiently free of rf 
interference at high power levels.

Don  K7FJ