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Comment by jlawrence6809 | Hacker News Reader

I just had claude walk me through refurbishing a Rohde & Schwarz signal generator from the 90s. It feels pretty cool getting a multi thousand dollar piece of equipment for 60 bucks even if you have no idea what you'll use it for.

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Was that by any chance the R&S AMIQ that I refurbished in an earlier blog post?

And yes, it's a lot of fun bringing these bargain bin pieces of kit back to life.

My model is an SMIQ03E actually! I've grown quite addicted to going to my local 2nd hand electronics store in recent months scrounging for anything with an rs232 port!

I looked for a SMIQ for quite a while to go along with the AMIQ, but eventually settled for the R&S SFQ TV test transmitter that you can see here: https://tomverbeure.github.io/2026/06/28/Rohde-Schwarz-AMIQ-....

It can be used a vector RF signal generator with I/Q inputs. The only limitation is the reduced input bandwidth.

Very cool! Yeah I lucked out finding mine. It was in the intake section at my 2nd hand electronics store. It had a broken power button so they were selling it "as-is". A button repair and battery swap later I have a 3.3Ghz VNA. Can't complain!

That's a great find, but afaict that model doesn't have VNA capabilities, does it? However, if you also stumble on a spectrum analyzer at that second hand store, you could combine them into a scalar network analyzer.

Oops yeah you're right, it's a VNG. A VNA would be great to have though! I wonder if these agents are going to just increase the utility of ever piece of equipment people can hook them to.

A friend of mine bought an SMIQ-03b on a whim, we've replaced the mmic amplifier chip that seems to always fail, now we're trying to figure out why the ALC doesn't work. It generates signals just fine, but the fine attenuation does nothing.

Yeah that pretty close to some problems I'm working on with mine. It has an "IQCON ALC loop failure" and claude was able to diagnose that the 2013 rail is around 11.44v (outside of the 10v range iirc) and the 2015 one is zero instead of the min of 0.13v. The RF paths looks mostly healthy as far as we can tell but I've only tried 10db steps and it seems consistently 4-5db low, assuming I'm using my oscope right.

Which MMIC did you replace? And what errors did you see? I have 110 and 111.

I'm not sure which he replaced, but having started trying to grok how it actually works, it's chock full of HFET and other amplifier chips, and over-stressed RF switches.

I'll report back if we ever get it actually working properly.

Did you fix it? What was wrong?

Some parts. It's still a WIP!

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