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G0HZU_JMR · 15th Feb 2018, 8:23 pm

I tested them all on the HP8405A VVM with the 30pF loading cap and the spread in frequency now seems a bit less.

The highest measured 4.032060MHz (+60Hz)
The lowest two measured about 4.031960MHz (-40Hz)

The others were within 15Hz of 4.032000MHz.

So even the worst one was just about in spec for IQD's 'initial' 15ppm calibration spec (with 30pF loading) and this is after 20 years sitting in a sample bag in a cupboard here

Note that I had to steal the rubber gloves from the kitchen when swapping between the crystals because the heat from my bare fingertips would cause several Hz drift and this would take a while to settle. I tried tweezers and mini grips but this was too fiddly. So I had to resort to donning the Marigolds

15th Feb 2018, 8:23 pm	#33
G0HZU_JMR Dekatron Join Date: Sep 2010 Location: Cheltenham, Gloucestershire, UK. Posts: 3,077	Re: Quartz crystal accuracy over time I tested them all on the HP8405A VVM with the 30pF loading cap and the spread in frequency now seems a bit less. The highest measured 4.032060MHz (+60Hz) The lowest two measured about 4.031960MHz (-40Hz) The others were within 15Hz of 4.032000MHz. So even the worst one was just about in spec for IQD's 'initial' 15ppm calibration spec (with 30pF loading) and this is after 20 years sitting in a sample bag in a cupboard here Note that I had to steal the rubber gloves from the kitchen when swapping between the crystals because the heat from my bare fingertips would cause several Hz drift and this would take a while to settle. I tried tweezers and mini grips but this was too fiddly. So I had to resort to donning the Marigolds __________________ Regards, Jeremy G0HZU Last edited by G0HZU_JMR; 15th Feb 2018 at 8:30 pm.