For those interested....the web page on the ARRL site that is referenced in=20 the October QST article is not there yet....I called ARRL this morning and=20 they haven't received the file yet but hope to do so soon. I do believe that the ARRL lab has a HP Z3801A GPS disciplined crystal=20 reference available to them (I've got two here on the workbench). Dino KL=D8S/4