[Today’s run: Watson Road]
I think I am getting down toward the finish of my GPSDO project. I need to do a bit of tuning. And, I need to eventually change the way my GPS antenna is attaching. Otherwise I think it is complete enough for the time being.
I started out with a chassis that had been some sort of heater controller unit. I was hoping I could use the existing +/- power supply for my control voltage source. But that supply failed when I started integrating all the parts. So I built a different +/- 5 VDC supply to replace it.
I also replaced my +12/+5/+3.3 regulator board because my 3-pin regulators were getting very hot. I measured the current to that supply at 0.5 A. I also reconfigured it so that the +5/+3.3 are downstream from the +12 regulator. I put a big heat sink on that +12 regulator. It is still getting hot, but I think I’ve improved the situation.
I’ve built at least 7 circuit boards for this project using the toner-transfer method. I’m getting better at it. One improvement is that I now upsize the traces and pads in EagleCad. There’s no reason to use hair-thin traces when all my parts are through-hole stuff and I’m working on power supply circuits.
I have had the GPSDO working and up to operating temp at least three times now. I want to get back to that spot and adjust the rough-tune so that my control voltage is as near to zero as I can get it. My previous runs have shown it having a frequency accuracy of around 0.001 Hz over a long term. Over the short term it is more like 0.1 Hz. That still beats anything else I’ve got.
(The green light on the front means it is “locked” to the GPS.)
