This is a good starting point, my horizontally (40' above ground) mounted OCF Dipole (balanced feed input) suddenly, only works on one band, 20 meters.

I use a Dentron Super Tuner Plus with a Yaesu YC-60 watt-meter to read reflected watts between transceiver.

I go to the settings I have transcribed for each band and, the reflected watts shows that the Tuners is not transforming the load to the radio; the SWR meter on the radio shows a "bad match".

I hooked my MFJ-259 Analyzer in place of the radio and tried the settings for the different frequencies; tuner doesn't tune balanced load.

Quote Originally Posted by kb2vxa View Post
One last thing, I have a bad feeling about this, the last time I heard a tuner "singing" it was internal arcing, the internal balun screaming in pain. This was surprising at first, an MFJ "3KW" tuner arcing with only 100W of AM, modulation struck the arc followed by the hiss of carrier arcing inside the balun. It was more the antenna system than the tuner, a 160M sloping open delta fed with open wire ladder line. It turned out the line was a half wave on the 75M AM Gangsta band sending the high RF voltage at the antenna feed point down to the tuner, baluns like current feed, voltage feed kills them. This is where the old Johnson Matchbox shines over today's tuners, it has a balanced output and one leg can be shorted to ground for unbalanced output, it laughs at high voltage.
There is no arcing or singing from my tuner, running digital power levels; nothing over 25 watts so, how would you diagnose a bad balun in a 2 Kw antenna tuner?