borrowing a handheld ph probe

[WheresTheReef]

Anyone near Gaithersburg or downtown Silver Spring have a handheld ph probe I can borrow for a day? I want to double-check the readings that my probe (connected to my DA RKL sl1) is getting. I got a reading of 7.47 yesterday (now back to 7.76) and want to make sure there is no interference causing noise in my wired probe's readings. I recalibrated to be sure and the readings remained the same as before. Thanks!