Doug Hall Electronics RBI-1 Remote Base Interface Mods

I have a RLC-II on my repeater 442.100+. On the RBI-1 all the tx audio lines are tried together all the time. Here are a two mods I have done to my RBI-1 on my RLC-II repeater to help with audio problems. I have very good reports on my transmit audio on my Kenwood remote base radios.

1) Add a 2.2k 1/4 or 1/2 watt resistor inside the 8 pin mic connector on the Kenwood radios mike plug in series with the tx audio line connected to pin 7 for every radio connected to the RBI-1. The resistor does a good job isolating the audio of the link radios.

2) Remove C5 and C6, add a jumper between C5 and C6. This mod eliminates op amp and tx gain adjustment, and noise pickup from the RBI-1 microprocessor on the transmit audio on the link radios. Since the tx gain op amp is bypasses, the only tx audio adjustment you will have will be on the controller.

A third mod I have not tried yet is to remove C8 in the RBI-1. Put a 2.2k 1/2 watt resistor in the place of C8. Take a .22uF cap and connect one end to the CONTROLLER SIDE of the new 2.2k resistor in position C8. Connect the other end of the cap to ground. This will put the De-emphasis audio filter inside your RBI-1, so you will need to disable the de-emphasis filter inside your controller.

Eddie Crawford, WA4QKC now SK, gets the credit for these mods.

Try these mods at your own risk, I assume no responsibility for any damage to your RBI-1, radios, or controllers.