[TenTec] Problem on 160 meters, Whats up?

[Steve Hunt]

1) Tuners struggle most when they're dealing with low impedances at low 
frequencies. So, using an electrically short dipole on 160m and then 
dividing the impedance by 4 is a bad idea - much better to use a 1:1 if 
you need a Balun.
2) As others have said, a current Balun is a better choice than a 
voltage Balun (transformer) because the core is energised only by the 
common-mode current, not by the full Tx power.
3) If the 4:1 voltage balun is wound on a powder-iron core, chances are 
it has nowhere near enough winding inductance to be acting properly as a 
4:1 impedance transformer.

So if your tuner has an integral 4:1 voltage balun wound on a powder 
iron core, it'll be a poor performer on all 3 counts.

73,
Steve G3TXQ