Los Alamos National Laboratory collected broadband radio frequency (RF) electric field change measurements from multiple detonations of high explosives (HE). Three types of HE were used: small cylinders of flake TNT, solid TNT, and PBX-9501. Low frequency signals (< 80 MHz) were shot-to-shot repeatable and occurred within the first 100 mu s at measured amplitudes of about 2 V m(-1) at 35 m distance. High frequency signals (> 290 MHz) occurred later, were an order of magnitude lower in signal strength, and were not repeatable. There is a positive correlation between the maximum electric field change and the shock velocity of the HE. The amount of free charge produced in the explosion estimated from the first RF pulse is between 10 and 150 mu C. This implies a weakly ionized plasma with temperatures between 2600 and 2900 K.