Hi Lee!
I was wondering if anyone has operated from one point where four grid squares meet.
I did that twice in 2006, from locations north of Dayton. I worked from EM79/EM89/EN70/EN80, then north of there at EN70/EN71/EN80/EN81. Photos of your GPS receiver's display or a video showing your GPS readout is now mandatory in terms of VUCC, if ARRL ever calls your operation into question (it was not the case, in terms of VUCC, until late 2008). You would want to have at least a couple of photos - one showing the GPS readout where you have "all zeroes" after the decimal points for the latitude and longitude, and another with the GPS along with your station. A video clip that shows all of that - a close-up of the GPS display, along with a wider shot of the GPS with your gear - is also acceptable for ARRL. You can be creative on how you set up your station on the spot, but the photos are good to have if anyone ever calls your operation there in question. You may want to review the VUCC rules, which explain what ARRL wants to see if they ever ask for documentation of your operation (specifically, sections 4e and 4f), at:
http://www.arrl.org/files/file/Awards%20Application%20Forms/VUCCRULE1a.pdf
If you go to that spot, make sure you are not trespassing - and that you can safely get to the spot and out of there when you're done. Most of the 4-grid intersections in Arizona are either in areas requiring a 4x4 vehicle or even a helicopter, or on private property (I regularly operate just south of the DM32/DM33/DM42/DM43 intersection on the DM32/DM42 line, since the 4- grid intersection is in farmland I won't walk onto without getting the OK from the owner). One of those spots here in Arizona is just over the edge of the South Rim of the Grand Canyon (DM35/DM36/DM45/DM46 - yes, I looked at that spot a year or so ago on a trip up there - so close!). A site that might be useful for you and anyone contemplating operating from a 4-grid intersection is:
(you'll need latitude and longitude for the 4-grid intersection when using this site, instead of the Maidenhead grid locators)
On the air, you would probably want to announce all 4 grids. You aren't required to, but why not mention that and attract attention to your unique location. At the absolute minimum, make sure all of the grids are all listed on the QSL cards. A photo of the GPS readout, as WA4NVM mentioned (and something that I and others do for our satellite QSL cards) would be great to have.
Good luck and 73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/