On Sun, Oct 6, 2024 at 10:52 AM, Martin - Southwest UK wrote:
Good work, but the LZ1AQ IOP3 looks far too low.
Hi Martin,
Sharp eyes! ?
You r correct, the LZ1AQ OIP3 looks too small. I think the problem lies in the large variation with freq - the OIP3 varies from 16 dBm at 5 MHz to 30 dBm at 20 MHz. In contrast, the competition - MLA-30+, M0AYF & PA0FRI have flatter OIP3 variation.
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My normal sanity check is to check that the IOP3 is typically 10 to 15dB higher than the P1dB value.
The |OIP3 - P1dB| in the table looks deceptively small because it is the worst case value, taken at different frequencies, i.e. P1dB is taken at 20 MHz, while OIP3 is at 5 MHz. If the OIP3-P1dB is taken at the same frequency, say 20 MHz, the delta is a more believable 15 dB (
see this graph). When I find the time, I will create another graph showing |OIP3-P1dB| vs. freq - hopefully, it will clarify things.
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What's your test setup, and how do validate it ?
FY6900 function gen, Minicircuits ZSC-2-4 hybrid combiner, & TinySA. I admit I haven't validated the setup.
Hi Everett, thanks for sharing your measurement results.
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73, Chin-Leong Lim, 9W2LC.
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