This 120V dc replacement relay system easily fits the SB200 Heathkit Amplifier. This fully sequenced system is also available to fit many other amplifiers. Please read the instructions and look at the pictures. The switching time is about 7mS, nearly twice as fast as the OEM relay. This system is also quieter than the OEM relay. This relay system is electronically sequenced. The important RF timing is shown in the posted storage scope pictures. There may be a slight appearance change as we switch to a revised board, but electrically and mechanically these boards will remain functionally identical. We also have RF antenna relays for other common RF amplifiers.