Ben, NO5K, ran some Smith Charts on a "pristine" V3.0 board (thanks Gene, WB4KTF) followed by ONLY changing the the relays to AXICOM relays .....same fixture setup, 50 ohm antenna termination, same cables, same test gear. The harmonic attenuation plots show somewhat better harmonics reduction with the AXICOM relays but the rolloff (a filter characteristic) is basically the same between the two as you would expect them to be.
The Smith Charts are basically the same between the two relays (Original and AXICOM) and tell the story. It's not the relays themselves in my opinion. It's the coupling from board layout, coupling between relays, coupling across relays, and wire routing ......resulting in wide swings from reflected capacitive impedance to reflected inductive impedance in the filter frequencies (.....like in filter passband frequencies, filter roll off frequencies, and filter stop band frequencies) and presenting that reflected waveform back into the PA section.? ?
As I mentioned earlier the AXICOM relays DO show improvement but it's not the whole story.
The attached charts are small, but can be expanded. The goal is to get the general idea.??
73 Kees K5BCQ
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AXICOM RELAYS
ORIGINAL uBITX RELAYS
