The F-33 is for laboratory and field testing. These probes have a small outer diameter, approximately 71 mm with an internal diameter of 32 mm. The usable frequency range of the series is from 1 kHz to 250 MHz. The F-33-1 has a typical transfer impedance of 5W ( ± 2 dB) over the frequency range of 5 MHz to 250 MHz. The RF current range is 10 amperes CW and 50 amperes peak with a duty cycle of 0.1. The maximum primary powerline current is 100 amperes from DC-400 Hz. The F-33-2 has similar dimensions to the F-33-1 and has a nominal transfer impedance of 1W from 150 kHz to 250 MHz ( ± 2 dB). The model F-33-2 handles 2 amperes CW, 50 amperes pulse and 100 amperes DC to 400 Hz.