I sent you a pm with some e caller info. If you get it built you can download tons of call sounds off of the links. I've been having good luck with wood pecker distress and rabbit distress sounds for fox. I haven't gotten any lynx to show yet. Are you set on a .204 or .17 for a predator rifle? Also was wondering if you are talking .17 HMR or 17. Rem.? The HMR would be great for fox or lynx I would think, but would be a little on the small side for coyote. I've got a Ruger all weather .17 HMR but I never carry it when I'm calling because I'm afraid it wont be enough gun. The 204 I think would do a fair job but I don't know a whole lot about it. I think it was originally disigned for blowing up prarie dogs though? I think probably the best all around cal. would probably be the .223. Just my opinion. You can ask around and I'm sure you will get as many different opinions as there are different rounds out there, in the end if you want the perfect round for every situation and animal, you will be carrying six different rifles around all the time.Good luck with you're discition.