Ok had another "I'll be screwed if I'm paying for something" moment and made another piece of test gear. It's Sunday so this is a "was made from crap lying around" project. I need an antenna analyser as I can't take my TDS210 and DG1022Z out without an inverter and massive car battery which is just stupid.
VU2ESE knocked up a design called a sweeperino which is an arduino, synthesizer and power meter that allows you to fart a signal out and then measure returned power. Basically a scalar network analyser, with some caveats but meh. I happen to have the wrong synthesizer IC dev board lying around, an Si5351, a arduino pro mini, a shitty LCR meter I didn't like and a power meter I built ages ago as a prototype for another one. So frankensweeper it is.
Early win... arduino, LCD and synthesizer IC. The synthesizer IC, the Si5351 is pretty damn cool and will quite happily hit 200MHz. I used it for a bit as a 2m CW transmitter on 144MHz by plugging in an antenna directly into it and stepping frequency and walking around the house excitedly jumping around making whooping noises as it worked. Then I limped down the road and it was still readable after about 500m. Then my foot hurt so I went back home. I might use one with an LPF and simple PA to build a little morse beacon. Really cool little IC and costs bugger all. LCD salvaged from LCR meter (which was a piece of shite if there ever was one). New hello world (deadpool 2 reference)...
Further down the line it got the power sensor (recycled), a control pot and a 7805 so I can run it off a 12v SLA or an AA pack:
I think it took an hour to rip out all the shite code, fix the frequency conversion stuff, wire in the Si5351 library (properly) and calibrate the frequency. I still haven't done the power calibration as it's too late and I'm too tired now but it mostly works! Showing (nearly) a 6dB loss on the RLB which is correct as it's also known as a 6dB hybrid. Phew...
Now the only dick about it is as it's a clock gen IC rather than a DDS with niceties such as aliasing filters, it has harmonic spurs so you have to think carefully about what it's telling you. It's good enough to use with the RLB to tune up an antenna though.
Edit: credit to VU2ESE (Farhan of bitx and hfsignals fame) for the basic idea and half of the code.