NavList:

Todd is quite correct.  A counterpoise may be worth a try where the receive problems are not solved.  Where the fundamental problem is an inability to receive WWV at all, then other solutions might be addressed first.  In a receive-only application it often makes no noticable difference, as the voltages (received signals) are low.  It will make a difference for very weak signals.  

It is important, if used, that the counterpoise is acting as such and not merely as some extension to the antenna.  I can explain that if anyone wants or needs me to.

That Todd's comments are correct is easily demonstrated if you have ever played with a simple crystal set receiver.  I still like to build these for fun.  My current crystal set will receive only one station during daylight hours without an earth ground, but will received several with it (this is a rural location and the AM broadcast stations are a good distance away).  I use a ground wire connected to a ground/earth prong of a three-point plug, where the other two prongs have been removed and replace by plastic.  This is super-simple means of connecting to the house grounding system and makes all the difference for receiving - and demonstrates the impact for very weak signals.  In a transmitter things need a more calculated  solution.

BTW, both WWV and WWVH and strong and clear right now in the U.S. West Coast at both 10MHz and 15MHz.  WWV only is clear on 20MHz.  This is with a simple magnetic loop receive antenna less than 30 inches ( 760mm) in diameter with no antenna tuning.  So the propagation gods are in a good mood today.

Murray