I made a new batch of the SFP Breakout Board.
With a 1 Gbit/s SFP transciever the bandwidth when transmitting from the TX port of one board to the RX port of another board seems to be almost 1.8 GHz.
Firmaliiga 2021/5 Kattilajärvi
Rainy and wet but quite warm. First a loop looking for #6 too soon, and then along the wrong hill towards #7..
Firmaliiga 2021/4 Haukkalampi
Start of the Firmaliiga fall season at Haukkalampi. Maybe +20 C and quite humid.
Lots of running along tracks/paths and then up/down a steep stony hill to fetch the control. Confused about the many paths inside the 1-2-3 triangle, then looked to early and too high for #6. Otherwise okish.
Husdata datalogger for heat-pump
I got this husdata datalogger for my heat-pump.
It plugs in to a 3.5mm audio-connector inside the electronics box of the pump. On an IVT geo 312C pump it's fairly easy to install by removing the big front cover, then a smaller black cover, and then opening the electronics-box. I routed the wire into the pump via a tube-hole at the top, and then through the cable-hole of the electronics box (lower right). It plugs into a 3-wire 'BBT' interface.
The datalogger reads info from the pump and broadcasts it over wifi either to the husdata-website or over MQTT to any compatible device.
Datalogger with interface cable. 
IVT geo 312C electronics box, with husdata-cable connected to BBT-interface 
Pump information as displayed on husdata website.
Partial solar eclipse 2021-06-10
Not-so-great phone camera picture through a small telescope of the partial solar eclipse on 2021-06-10 from Espoo, Finland.
See also:
Firmaliiga 2021/3 Rinnekoti
The start was on a road wher this crazy youtuber did an everesting...
Drifted onto the wrong hill at #8, otherwise mostly ok. Not the nicest terrain to run in... +15C and sunshine.
Firmaliiga 2021/2 Salmi, E
+11C and rain. Quite slippery. Maybe too safe via #4 to #2. Small loops into #6 and #8, but mostly OK orienteering.
Firmaliiga 2021/1 Solvalla
Short E-course in sunny and warm weather. A small loop into #5, and then drifted too much east into #7.
Salmi next week.
200MHz photodetector with OPA818, FGA01FC InGaAs photodiode, and RF=4k7
Here's another one-inch-photodetector using OPA818 with a 2pF@5V InGaAs fiber-coupled photodiode FGA01FC. With a transimpedance gain of 4k7 Ohms the bandwidth is just over 200 MHz. A TIASim model predicts the dark-noise and response reasonably well with a parasitic capacitance (over RF) adjusted to ca 0.12 pF. The spectrum-analyzer settings weren't ideal for looking at the dark-noise which should go down to the thermal-noise of the 4k7 resistor (dashed line) - but here the instrument noise-floor prevents us from seeing that.
88Sr+ clock with new mu-metal magnetic shields
With new thicker solid mu-metal magnetic shields (2 layers), the clock transition in our 88Sr+ experiments shows a transform-limited linewidth of ca 10 Hz using a 72ms probe pulse. More testing to follow, as we try to lengthen the probe-pulse and search for the ultimate linewidth limit.