[time-nuts] Vanguard TCXO

Thomas Allgeier th.allgeier at gmail.com
Thu Feb 8 06:23:10 EST 2018

Hello All,

This is for the medium-precision nuts amongst us. I have invested £14.50 
in one of these Vanguard 0.1ppm TCXO's to pimp my Siglent FG which has a 
footprint for it. It is its internal ref at 25 MHz. The swapping-in was 
simple to do and the FG works fine with it. Since it has a counter mode 
I did a quick check to show whether it was worthwile: I made it count 
the 10 MHz from my Proteus GPSDO. The Siglent reads to 1 Hz and straight 
after turn-on it went straight to 10.000000 MHz. Over about 1 day I 
never saw it more than +/-1 Hz off, and this involved a deliberate 
temperature change of just over 5 deg C, basically by having the heating 
in the room off and on. For most of the time the display sat solidly at 

So, to summarise, in a rough sort of way the thing lives up to its 
0.1ppm spec, at least around the 20C temperature mark. I bought it from 
a Hong Kong seller on Ebay - naturally there is always a chance that 
other devices sold with the same description/label might not perform as 

I'm quite aware that the generator (DDS) suffers from other sources of 
error, which won't be improved by the clock being better, but at least 
the nominal frequencies it outputs are now going to be very close to the 
mark without the need for an external ref.

Kind regards,


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