azonenberg changed the topic of #scopehal to: libscopehal, libscopeprotocols, and glscopeclient development and testing | | Logs:
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<azonenberg> Just VNA'd two of the AKL-PT2 first-run unuts (A68-001 and A69-012, chosen at random) and... they're very consistent up to about 1.5 GHz but then there's some significant variation
<azonenberg> Wondering if it's SMA soldering or something else
<azonenberg> My plan is to wait until the scope comes in then fully VNA and time domain measure all of them
<azonenberg> then try to correlate performance to details of sma alignment and see if anything jumps out at me
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<azonenberg> Here's three AKL-PT2s compared. Only A69-006 has the 6 GHz performance I'm looking for, all the rest have bigger ripples and higher loss
<azonenberg> Don't yet know why
<azonenberg> I think i'm going to go through this whole batch and bin them
<azonenberg> keep the good ones for further testing and sale
<azonenberg> then offer the less good ones as "grade B" or "factory seconds" probes sold at a discount
<azonenberg> No warranty, known to not meet spec, but generally pretty decent to a few GHz
<azonenberg> Upon preliminary inspection: A68-001 has damage to the SMA dielectric, probably because i recycled the connector off a previous experiment
<azonenberg> A69-012 looks to have a misaligned resistor
<azonenberg> Not enough data yet to know if those are the root cause of the observed defects
<monochroma> :o
<azonenberg> But it seems like getting good performance out of these probes is going to depend on relatively tight process control and solid QA
<azonenberg> (Neither can be reworked as the issues weren't found until everything was epoxied down)
<azonenberg> So i'm going to want to do *very* thorough visual inspections of everything after soldering before i apply the epoxy
<monochroma> yeah
<azonenberg> electrical testing really has to happen post epoxy though, i dont want to be soldering right next to the tip resistors or torquing SMAs that arent reinforced
<azonenberg> anyway, i figure i can probably still sell the rejects for $50 or so. They're still perfectly usable ~3 GHz probes
<azonenberg> better than ending up in ewaste
<azonenberg> but i need to carefully identify root cause for all of the bad ones and figure out how to improve process uniformity to get acceptable yields
<azonenberg> AKL-PT1 v1.4 prototypes arrived
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<monochroma> :O
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