UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Radio Wrangler · 15th Feb 2018, 5:10 pm

Yeah, you just drop a resistor into your fixture in place of the crystal to give you a phase=0 reference. Fiddle with the resistor value to get the same voltage ratio on the two VVM channels and your resistor value equals the crystal ESR, and you have the best zero phase reference.

The Cathodeon fixture with its low-Z environment between its minimum loss pads is rather good in this area. Find the SER this way, and find the series res frequencies with and without the 30pf load C in circuit and you have enough to extract motional parameters.

There are some superb apps notes by Cathodeon, but I've never seen them on the web.

David

15th Feb 2018, 5:10 pm	#27
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,898	Re: Quartz crystal accuracy over time Yeah, you just drop a resistor into your fixture in place of the crystal to give you a phase=0 reference. Fiddle with the resistor value to get the same voltage ratio on the two VVM channels and your resistor value equals the crystal ESR, and you have the best zero phase reference. The Cathodeon fixture with its low-Z environment between its minimum loss pads is rather good in this area. Find the SER this way, and find the series res frequencies with and without the 30pf load C in circuit and you have enough to extract motional parameters. There are some superb apps notes by Cathodeon, but I've never seen them on the web. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done