Hi Jim, I gotta get back to work but......
>>More likely you changed the impedance presented to the >>tank >>circuit on the second harmonic. > > The coax I was changing was between the K3 and the amp. When we measure a change in a complex soup of interactions and fields formed by the interactions, we might never really know what we really changed or how we changed it. There could be a half dozen things going on, including that the actual harmonic never really changed in level at all. Collins fell into this trap with the unneutralized 30L1. The 30L1 amp, because it lacks neutralization, has inherent instability and regeneration problems. They started playing with coax between the amp and exciter, saw changes, and came up with a long fairy tale about 180 degree phase inversions in the coax between the exciter to amplifier coax. Unfortunately the conclusion they reached can be fully disproven in a matter of just minutes by observing the same things they did in a different way. Anyone thinking the coax shield has such a large effect needs only directly measure egress or ingress through the shield to see how little worry about the shield at HF is actually warranted. We are in a thick soup of radiation from our antennas, and even the worse cable shields "leak" far less than the fields from direct radiation. Far more important are common mode currents from poor antenna design, poor cabinet bonding, poorly thought out groundplanes, bad PC or wiring layouts, and poor connector mounting. Coax shields are way down the "problem" list at HF. 73 Tom ______________________________________________________________ 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
