On 11/15/2010 3:43 AM, pastor...@verizon.net wrote: > I have noticed when I fired up my amplifier on 40 meters that the SWR reading > on the K3 when I tune up is higher then when I tune up on standby. When a rig drives an amp, it does not "see" the antenna, it sees the input circuit of the power amp. When the amp is in bypass mode (that is, not in the OPERATE mode), your rig DOES see the antenna. What you are seeing is some mismatch between the K3 and the power amp, which is the result of the input circuit of the power amp not being a perfect match to 50 ohms. This is QUITE NORMAL for most power amps. You should only worry about this if that SWR is much more than about 2:1. Most rigs, including the K3, will "fold back" (reduce power) to protect themselves if the SWR gets too high.
As long as the K3 provides enough power to drive the amp to the desired output level, don't worry about it. With some amps, you can engage the K3's antenna tuner and tune it to provide a better match. That depends a bit on how the amp is being keyed. It is also common for the mismatch to vary from one band to another, and from one place on the band to another. In most power amps, the input circuit includes some form of bandpass filter. 73, Jim Brown K9YC ______________________________________________________________ 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
