开云体育

On Aug 26, 2019, at 9:19 AM, Warren Allgyer via Groups.Io <allgyer@...> wrote:

Jerry

My scope will not do 600 MHz but my spectrum analyzer will.

Here is a trace of the S11 output showing two, 100 MHz sweeps centered on: Yellow = 300 MHz and Purple = 600 MHz.

The Yellow 250 - 350 MHz sweep starts at Marker 1 and sweeps to Marker 3 on the fundamental. It then, at 300 MHz, jumps back to Marker 2 at 100 mHz and continues to 133.333333 MHz to produce the output from Marker 3 to 350 MHz. Note the discontinuity at 300 MHz (Marker 3) where the switch is made to using the harmonic and the level is boosted (Marker 2 level versus Marker 1).

The purple sweep spans 550 to 650 MHz and all is generated as the third harmonic of the fundamental from 183.333333 - 216.666667 MHz (Sorry…. ran out of markers). Note that the resulting 550 - 650 MHz sweep has no discontinuity. This is because there is no level or harmonic transition taking place at 600 MHz.

The clean sweep at 600 MHz versus the “steppy” sweep at 300 MHz is what leads me to conclude that the 600 MHz “spike” is simply a harmonic of the 300 MHz transition. As I write this I am thinking that would be easy to prove by sweeping any range that includes 600 MHz but excludes 300 MHz. I am betting there is no spike at 600 when sweeping say, 450 - 750 MHz. I have not checked that because I am not in the lab at the moment.

In any event I would continue to maintain the “spikes” are immaterial to the operation of the instrument.

WA8TOD