Lady Heather and GPSDO

A while back I purchased a GPS Disciplined Oscillator (GPSDO) off of ebay.  The idea here is that this device receives the GPS signal and from the 1pps signal it can generate a very accurate 10MHz reference signal.  This can be useful to ensure your transmitter isn’t drifting with temperature fluctuations.  I hope to eventually pipe this into a PLL circuit to get 116MHz and make that the local oscillator for the transverter like these guys did.


I was pretty shredded after work yesterday and didn’t feel much like soldering so I dug this thing out to play around with.  The unit I received is an older Thunderbolt by Trimble.  Apparently a large number of these were ripped out of cell tower sites and are now available on the surplus market.  Lucky us!  After figuring out which serial port it was hanging off and editing the heather.cfg file I fired up the Lady Heather application written by KE5FX.


This is a pretty neat application and will provide some additional functionality when operating EME in the field.  You can see right in the middle of the screen is the azimuth and elevation of the moon.  You can display this in wsjt-x as well but I’m not sure if that is dependent on an internet connection at all.  Either way a second source doesn’t hurt.

The other more important piece of this and maybe even more important than the disciplined oscillator is that this device can update the system time of the computer.  Obviously timing is important when it comes to JT modes and almost certainly QRA as well.  According to the readme file it’s not an elegant way of updating the system time but it works (when it’s running as administrator on Windows 10).

After letting the device acquire a GPS lock and settle down I hooked it up to the frequency counter.


I’m not sure what kind of accuracy I should be expecting but this is probably good enough for government work.  I’ll most likely end up getting an active GPS antenna even though the tiny patch antenna i’m using indoors seems to be fine.

I’m still waiting for my wife to notice the new icon on my desktop:

lady Get it?  Disciplined Oscillator!

I also printed off a holder for my soldering tips!










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