Addendum: I have my HT20 paired up with an R-390A in a rack. The paints match exactly and the HT-20 covers all freqs between 160 and 10 meters. Good matchup for continuous coverage 1.8 to 30MHz. I did an audio sweep on it years ago and it was 50-10000 cps +-3dB. Good quality. I don't think Halli spec'ed it that wide, though. Perry w8au