The following lines were added (+) and removed (-):
3-500Z - Heathkit SB-220 and [[Heathkit SB-221 HF Amplifier]] uses 2. Other brands also use, Ameritron, Henry, etc.. 3-500Z - Triode. Heathkit SB-220 and [[Heathkit SB-221 HF Amplifier]] uses 2. Other brands also use, Ameritron, Henry, etc.. 572B - rf tube seen in ham radio. [[Dentron 160-10 HF Amplifier]] uses 4 572B Tubes. 572B - RF tube seen in ham radio. [[Dentron 160-10 HF Amplifier]] uses 4 572B Tubes. 4-400 - Tetrode RF tube