Mike, Your analysis of combinations is correct. But the KXAT2 should be compared to the KXAT3 (etc.), not the T1. Here's why:
The KXAT2 only has to cover 80-10 meters. The KXAT3 has one additional L and C, but it has to cover 160-6 meters. Over the range of 80-10 meters, for virtually any field antenna, the KXAT2 will perform just as well. The T1 also has to cover 160-6 meters. To do this with 7L/7C, the L and C values in its array are spread out with a ratio of slightly greater then 2:1 from one to the next. This allows the array to cover a wider range of load impedances, but with an average final SWR more like 1.5:1 than 1:1. The KXAT2, like the KXAT3, uses a ratio of very close to to 2:1, so average final SWR is very close to 1:1. 73, Wayne N6KR On May 24, 2016, at 9:05 AM, Mike Morrow <[email protected]> wrote: > Bill wrote: > >> As to the ATU in the KX2, 7L/7C is the same range as the KX1, T1 and >> I think the K2 ATU. > > That is wildly inaccurate, especially for the KXAT1 ATU!!! > > The reactance configuration for all Elecraft ATUs is an L-network of series > inductance, with a capacitance connected to common before (radio side) or > after (antenna side) the inductance (but not both) by a relay. It is a > classic simple low pass filter. > > The total number of possible configurations in such a filter of L inductors > and C capacitors, with the capacitor bank capable of being connected to > either side of the series inductor, is: > > Different Configurations = ( 2^L x 2^C x 2 ) > > Four (4) "don't care" (non-unique) configurations should be eliminated from > total: > 1. Capacitor bank connected to inductor input, but all capacitors open. > 2. Capacitor bank connected to inductor output, but all capacitors open. > 3. Capacitor bank connected to inductor input, but all inductors shorted. > 4. Capacitor bank connected to inductor output, but all inductors shorted. > > USEFUL Different Configurations = ( 2^L x 2^C x 2 ) - 4 > > For Elecraft transceiver ATUs before the new KXAT2, here are summaries (N is > the network variable...capacitor connected to input OR output of inductor): > > KAT1 (4L/5C/N) Configs=1020, L=0 to 4.9 uH (16 steps), C=0 to 300 pF (32 > steps) > > KAT2 (8L/8C/N) Configs=131068, L=0 to 20.7 uH (256 steps), C=0 to 2420 pF > (256 steps) > > KAT3 (8L/8C/N) Configs=131068, L=0 to 17.4 uH (256 steps), C=0 to 2600 pF > (256 steps) > > KXAT1 (3L/3C/N) Configs=124, L=0 to 4.5 uH (8 steps), C=0 to 140 pF (8 steps) > > KXAT3 (8L/8C/N) Configs=131068, L=0 to 15.9 uH (256 steps), C=0 to 2680 pF > (256 steps) > > T1 (7L/7C/N) Configs=32764, L=0 to 7.5 uH (128 steps), C=0 to 1300 pF (128 > steps) > > Many already have the new KXAT2, but no circuit value information has yet > been provided to those of the great unwashed masses like myself. All I've > seen is its description as 7L/7C/N, just like the T1. If that is correct: > > KXAT2 (7L/7C/N) Configs=32764, L=0 to ?.?? uH (128 steps), C=0 to ???? pF > (128 steps) > > The KXAT1 generates 124 unique matching network configurations. > The KAT1 generates 1020 unique matching network configurations. > The KXAT2, T1 generate 32724 unique matching network configurations. > The KAT2, KAT3, KXAT3 generate 131068 unique matching network configurations. > > Conclusion: The KXAT2 is comparable ONLY to the T1. > > 73, > Mike / KK5F > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
