On Sun, 7 Dec 2014 21:53:48 +0100, you wrote: >Something that keeps a constant temperature that is that I can then >glue/solder to the crystal of those systems. A ready to go version (QH40A): http://shop.kuhne-electronic.de/kuhne/en/shop/amateur-radio/accessoires/crystal-heater/Precision+crystal+heater+40%C2%B0+QH40A/?card=724 Angus