Hi Wayne, Thank you for your prompt and informative replies. When I first ran my experiment the results I got rather surprised me.
Now you have explained the fact that the KAT3 is never really out of circuit even in BYPASS mode, and is seeing strays which the LP-100 does not, clarifies the situation. Most of the time, because of my antenna setup I use a fully balanced external tuner, and the exact SWR presented to the K3 is shown on the LP-100. Of course, as others have pointed out the value of SWR measured is immaterial, as the KAT3 will try and adjust to 1:1 when it is selected. 73 Stewart G3RXQ On Wed, 4 Nov 2009 07:50:35 -0800, Wayne Burdick wrote: > Hi Stewart, > > The KAT3, like all wide-range ATUs, has significant stray reactance, > especially on the higher bands. When you tuned it into 50 ohms, you > created an L-network on each band that tunes out this reactance--at > that one impedance. > > In your test, the KAT3 is between the K3's SWR bridge and the LP100, > so the two bridges are looking at different points in the network. So > changing the load Z to 25 ohms affects the two readings differently. > > The disproportionate error on 20-15 m reflects the nature of the > KAT3's strays. On these bands, the stray-cancellation values that it > automatically finds results in an L-network. On still higher bands, it > may look more like a Pi network, which could explain why your SWR > error delta is lower on 6 meters. On the lower bands, the strays are > less significant, so the readings match. > > If you removed the KAT3, the readings would be in closer agreement. > > 73, > Wayne > N6KR > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
