[TenTec] TenTec 228 - TenTec 229 ATU

[Marinus Loewensteijn]

The 228 uses a 42 position switch for switching the inductance, the 229 has a roller inductor. When the power amplifier stage consisted of tubes the roller inductor with its "infinite" adjustment was a very fine thing to have.
Another advantage that a roller inductor has is that the self capacitance is very low which means a far higher self resonance for a given inductance.

I wonder if a roller inductor is still an optimum solution with semiconductor output stages. I view a switch as self cleaning and a roller inductor imho as requiring (little) maintenance to prevent arcing. Arcing (in my book) is a sign of not making proper contact which means that the output stage is not properly loaded and this is potentially damaging the semiconductors in the output stage.

Would the 228 with its T circuit and switched inductor be a better ( mechanically, contact wise )  solution than the 229 with a roller inductor? Or am I missing something here?

PS This is not to replace my S-Match for balanced output ( twincom / open wire ),  purely interested in driving a (unbalanced) coax system ( some phased verticals ).

Thanks for your input, 73, Marinus, ZL2ML

_________________________________________________________________
Free Windows Live software. Chat, search, share pics and more
http://get.live.com/