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Radio Wrangler · 26th Mar 2018, 10:45 am

That crystal needs to be in an oven and it needs to be at the right temperature. The cut of the crystal won't be the usual 'AT', it will be designed to have a parabolic freq/temp curve with a flattish nose at usually +80C so the tempco at the oven's operating point is minimal.

Down at 25C the tempco will be alarming. The 10544 and 10811 families would be a kilohertz off frequency or more.

If you bought an ordinary grade counter, analyser etc with a TCXO it would get onto frequency fairly quickly. If you paid more for the OCXO option, the frequency accuracy would be far worse until the oven got to temperature, and then the precision of the ocxo would be about 2 orders of magnitude better than the TCXO.

David

26th Mar 2018, 10:45 am	#7
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: HP 5245L counter crystal oscillator That crystal needs to be in an oven and it needs to be at the right temperature. The cut of the crystal won't be the usual 'AT', it will be designed to have a parabolic freq/temp curve with a flattish nose at usually +80C so the tempco at the oven's operating point is minimal. Down at 25C the tempco will be alarming. The 10544 and 10811 families would be a kilohertz off frequency or more. If you bought an ordinary grade counter, analyser etc with a TCXO it would get onto frequency fairly quickly. If you paid more for the OCXO option, the frequency accuracy would be far worse until the oven got to temperature, and then the precision of the ocxo would be about 2 orders of magnitude better than the TCXO. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done