Well the original X1 crystal is clearly 25MHz too, so it makes sense to replace it with a 25MHz TXCO. He also has an SDG1025, not an SDG1010. So I really don't understand your suspicion?
Now I just have to install the new TCXO in my SDG1020 and see if it works. It hope it is the right size. It looks so small.
is there a measurable difference?
I installed the TCXO yesterday and used the SDG1020's frequency counter to measure a 10 MHz Morion MV85 OCXO (Uin not connected, so the frequency is pulled >0.5 ppm (between 5 and 10 Hz) below OCXO middle value)
With the original 25 MHz crystal installed, the SDG1020 measured
9,999830 MHz (-17 ppm) 9.999849 (-15.1ppm)
With the 25 MHz 0.1 ppm TCXO installed, the SDG1020 measured 9,999996 MHz (-0.4 ppm)
EDIT 2015/03/13: My SDG1020 with the 0.1 ppm Vanguard TCXO outputs 9.9999990 MHz when set to 10 MHz (that is exactly 0.1 ppm low). Measured with a HP 5315A frequency counter with OCXO option installed, calibrated using a Rubidium (FE-5680B) frequency standard.
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My HP 5315A measures the 10 MHz OCXO a little high, at 10.000015 MHz. No longer the case - standard XO replaced by OCXO
2 hours ago, I ordered the parts at Farnell that I need to fit the MV85 OCXO onto the PCB by amc184 that goes into the 5315A as the new frequency reference. And now I just received an email from Farnell stating that the order has shipped from their warehouse in UK. Pretty fast handling. I will not be surprised if the shipment is delivered to my door (in Norway) by tomorrow.
EDIT (17 hours after order was placed):
Farnell element14 (or UPS) is hauling ass with my 100g parcel - 1468 miles driven in ~10 hours (after departure scanning in Leeds):
Google map routeVery impressive. They are obviously serious about logistics.
Gardermoen, Norway 16.12.2014 07:59 Departure scanning
16.12.2014 07:15 Importskanning
Oslo, Norway 16.12.2014 06:28 Arrival scanning
Malmo Sturup, Sweden 16.12.2014 05:18 Departure scanning
16.12.2014 04:17 Arrival scanning
Koeln, Germany 16.12.2014 02:56 Departure scanning
16.12.2014 01:08 Arrival scanning
Castle Donnington, United Kingdom 15.12.2014 22:52 Departure scanning
15.12.2014 21:10 Arrival scanning
Leeds, United Kingdom15.12.2014 20:55 Departure scanning
15.12.2014 19:19 Export scanning
15.12.2014 19:19 Origin scanning (or something like that)
United Kingdom 15.12.2014 13:32 Order handled: Ready for UPS