[TenTec] OT Antenna Tuners

[Marinus Loewensteijn]

The TenTec design is OK but it would requrie an extra switch and if really getting down to the nitty gritty it is no longer a pure L-match.

There was an article in the ARRL Antenna compendium vol 3 that stated that for an ATU used for a coax match it should be able to match up to an SWR of approx 4.5. There were some valid reasons for that, cannot remember exactly what those were. The implication was that if it is higher then the antenna needs first to be matched closer before attaching it to the coax.

One option could be not to use 450 Ohm but something like a 300 which would make matching on the highest HF bands easier. I saw some two toroid design for this but did not investigate this further for two reasons: an extra toroid ( more stray capacitance impacting matching and also an extra toroid would introduce more losses) and secondly I am not interested in the bands above 21 Mhz.

Alternatively it would be quite feasible to use a tap somewhere on the third winding and I think it would work FB. I'll make a note of this should I ever get the urge to open the ATU up again and make adjustments enabling higher band functionality. I suspect that more capacitance will be required on the low bands.

73, Marinus, ZL2ML


_________________________________________________________________
Get inspired - dream, research, plan and book your next holiday online with MSN NZ Travel 
http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Ftravel%2Emsn%2Eco%2Enz&_t=771497011&_r=MSN_NZ_travel_hmtagline&_m=EXT