Check the listing for details. Amplifier keying relay buffer interface TWO radios 2 linear switching with PS. Condition: New. Listed at 109.95 USD. ONE or TWO radios keys ONE or TWO amplifiers with bypass switch High quality relay box to interface between any TWO radios and will key any TWO amplifiers Switch chooses ONE of TWO radios that will activate BOTH amplifiers or noise cancelling units or choose center switch position to bypass the amplifiers Many newer radios can only provide for a small amount of current on the external amplifier keying output.Better SAFE than SORRY! In response to your requests for a relay interface box that will key TWO completely separate amplifiers, we have developed the RBI-2a. Do you have a need to key TWO amplifiers (perhaps a driver amp and high power amp) that have two different keying relay voltages? Our RBI-2 can (for example) key one amp with a 120 VAC T/R relay and your other amplifier that uses a 12 VDC T/R relay (or ANY voltage and current up to 240 volts ac/dc @ 5 amps for EACH amp). The keying circuits in our RBI-2a are COMPLETELY SEPARATE from each other and the radio is isolated. EACH output is a relay closure from center conductor of the RCA jack to the outside of the RCA jack. EACH output uses a completely SEPARATE relay! WHY use two amplifiers? Some users want to extend the life of their radio's expensive final transistors by running low power from their radio into an intermediate amplifier and have that amplifier run only what is needed to get full output from their higher power amplifier. Some users want to use an "instant on" amplifier for most contacts but still also have a larger amplifier what may require warm up time that is less frequently used. With our box, you do not need to reach in back to disconnect and reconnect each amplifier keying line. Some users have dedicated amplifiers for different bands and antennas and also don't want to to disconnect and reconnect individual relay keying cables Our box will draw