Radio and rails...

After a life in IT you'd think I would be better at this stuff. Two things caught me out this week, both around the web server that runs this blog among other things. The first knocked it offline and I was unaware. The server is a dimimutive Lenovo ThinkCentre M92p and has 4 USB ports but none work which was annoying as I wanted to upgrade Lubuntu but really wanted a decent backup to an external device first. I had another of these systems with working USB ports so I swapped the hard disk between the two - the specs are essentially the same. All went well, apparently. I attached a USB SDD to use as a backup for the pending operating system upgrade. Then I noticed no incoming email plus I tried to access the blog from an external IP and it failed. Odd. No issues with accessing from the house LAN. Then I remembered having an issue with the PlusNet router but could not remember what so I logged into that to see if my memory would return. And it did. The PlusNet router helpfully follows MAC addresses rather than IP addresses so when I swapped the HDD…

Finally I have a rubidium 10MHz oscillator to play with. It is a Symmetricom X72 that needs between 10 and 32V input, so the shack supply will be fine. It came built into a case which also has a power and unlock LED on the front plus a fan. Why you ask? Well, I do not really know but I wanted one! Once it arrived I checked it over and powered it up. It took aroud 4 minutes for the unlock LED to go out and it has been giving a constant 10MHz sinewave frequency output since then. The unit has a 1pps input and output plus a serial interface which I have yet to investigate. It is also apparently controllable with the Lady Heather control program, something else I have yet to play with.

I finally got myself one of the BG7TBL 10MHz distribution amplifiers. I (will) have a few devices that need a 10MHz input for frequency stability so this is handy. It actually came from China via Aliexpress a lot cheaper than similar (and rare) offerings on eBay, and it only took 5 days. Anyway, here it is: The 10MHz source is coming from the DX Patrol GPSDO and as a test one output is to a 'scope and one to a counter. Rather unexpectedly (to me) it takes a square wave feed from the DX Patrol but gives out 8 separate sinewaves. Of note, the voltage input is specified as 11.7 to 12.9V, not the usual 13.8V. But as I need 12V for the Winterhill and the 13cm transverter I already have 12V around the place. Although this one says it has an OXCO this one does not - it is an option but I decided against it. I have a decent 10MHz OXCO if I ever need it.

Yes, ok, this is still not about the transmission path! But I wanted to experiment a little more with the wideband part of the transponder and DATV signals. To that aim I press ganged the small HD screen from our NVR (which in turn will be wired to the large TV downstairs) and attached it the the Winterhill box. With 12V from the lab supply to the Winterhill and the 25MHz LO being fed from the diminutive Leo Bodnar mini GPS reference clock it all appears to be working as expected. This was covered in Part 2 already but today I managed to get a screenshot with four DATV feeds, although one had just dropped leaving the last image that was received. Now I need to decide whether to keep this small screen for Winterhill or swap screens with the one I use for Hamclock with the latter then on the smaller screen. I will probably do the latter as this small screen will run from USB C from the PC meaning one less socket.

Some days ago the diminutive DX Patrol GPSDO (v3, multiple outputs) would quite often lose PPS and coordinates. At first I thought it was the GPS signal as it is still only using one of those little puck type antennas stuck to the window. On recommendation I placed this on a metal sheet but the problem persisted. Also, checking the antenna against other GPSDOs showed it worked fine. I plugged the USB into a PC to see if there was any errors and for the duration of that the device functioned perfectly with no dropouts. This was with both the 12V supply and the 5V from the USB powering the device. Long story short it transpires that when the GPSDO is running from the 12V shack supply it keeps dropping out. The supply is fine. When just powerd from USB it works fine. So that's the way it has been left now. It has the advantage that I can see the data output but the annoyance that the USB socket is on the front - however, a down bend USB adapter plus a down bend cable neatly brings the USB lead back under the GPSDO. As I understand it a…