Ed: The KAT500 does open up the PTT line and tunes at low power. An early step in that tuning measures the SWR of your 14:1 antenna with the KAT500 in its bypassed relay configuration. Then the ATU finds the reactive components needed to match your antenna. The "bypass VSWR" is retained in each tuner memory and is used to evaluate the power that the ATU can safely handle. Should you exceed this power, for example 1000 watts into an antenna that was originally 14:1, the ATU faults.
I would recommend "Transmission Lines for Windows" (TLW), a computer program written by Dean Straw (N6BV), available in recent editions of the ARRL Antenna Book, to evaluate tuner component stresses at various antenna impedances. Our tuner configuration is what Dean calls a "Low Pass L network". High power high SWR results in some surprisingly high tuner voltages and currents. The KAT500 is robust, but the components have limits related to the advertised KAT500 capability. 73 de Dick, K6KR -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ed G Sent: Thursday, November 15, 2012 1:57 AM To: [email protected] Subject: [Elecraft] KAT500 Matching Range & Power Limits Hello, I'm trying to understand what the KAT500 power limits mean in real life. If I am tuning an antenna that initially shows a very high SWR (say 14:1), and I am using high power (say 1000 watts out), the KAT500 is going to open up the PTT line, and the tuning operation will take place with less than 100 watts. Then I will show a 1:1 SWR, and I'm ready to go with my 1000 watts. Operationally, what is the meaning of the 3:1 SWR limit for 1000 watts as shown in the KAT500 specs? Will the KAT500 fault because it is matching a 14:1 SWR at high power? --Ed-- ______________________________________________________________ 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 ______________________________________________________________ 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
