Quote Originally Posted by N8YX View Post
Here's a size reference:

CR1.jpg

The -18 can either have wire leads or pins.



I noticed the Digikey and Mouser carry devices of the required frequency, but the load capacitance (10pF series) is wrong. Needs to be on the order of 25-32pF parallel.



Unfortunately, no. The 12.800MHz oscillator is divided down by a series of 7493 counters to get a 2.5Hz gating frequency; if the gating window is longer or shorter than this by even a small amount then the counter isn't accurate. The trimmer circuit as designed won't allow a 12.900MHz rock to be pulled enough to work.
How about an osmod? The outputs are are typically high enough that loading won't be a issue, and depending on what you get, all you need is 3v, 5v, or 12v. Accuracy is quite high so the trimmers won't be necessary, wouldn't affect the frequency anyway. I don't think the clipped sine would be an issue, either. They only cost a couple of bucks and would be worth a try until you can find a rock that will work, or have to order one from ICM or Jan. You can get pure sine units, but they are higher than giraffe nuts. I'll keep looking around. I'm sure we can find something cheap or broken somewhere that uses them.

http://search.digikey.com/us/en/prod...2-2-ND/1024654