HP 3582A ELF/Audio FFT Spectrum Analyzer HP3722A Gaussian/Binary Noise Generator HP8566A, Low Frequency Spectrum Analyzer Plug-in (0 to 30 KHz, 0 to 300 KHz). Original Manual for HP8903A Audio Analyzer Magnetic Field Intensity Meter (H-Field), 0.01 Hz to 50 KHz with calibrating Helmholtz Coil. Dr. Gar Ko garwonko at msn.com