I recently bought an Omni VI Plus. It was an estate piece... "lights up, receives, no antenna to test transmit." Yeah, I know. Despite the big red flag, I bought it anyway. Everything seems to work fine... except for one little thing... Transmitted RF is getting into the receiver! I have a problem with the LPF board that I can't pinpoint, and I'm sure I must be overlooking something obvious. Using my Astron RS-35M power supply, Kenwood SW-2000 Wattmeter, and Drake DL-1000 dummy load for testing. Key down, start dialing up RF power, and output stops increasing on my Wattmeter at about 40 Watts, but PS current continues to climb to about 23 A. The little resistors on the Front End board which form the Attenuator got toasted. Disconnect the coaxial cable from the LPF board at J17 (the feed to the receiver) and the transmitter works as it should, with all 100+ Watts going out the Antenna jack. Below is a snip of the schematic with my voltage measurements added in. When I first started working on the rig, I found D6 literally blown off the board! (lightning strike?). I have replaced D6-D8 (1N4007) and D9-D14 (1N4148)... diodes are cheap. All of the measured voltages seem reasonable and I don't see why the diodes are not blocking the transmitted signal from the receiver signal path. Here is the circuit description from the TT manual: "During transmit, relay K1 is closed and passes the filtered PA output to the Main Antenna connector. A small sample of the transmit signal is passed through C12 to voltage doubler D11 - D14. They develop about 150 volts of reverse bias for diode switch D6, D7, and D8 to protect these diodes and prevent the transmitter signal from leaking into the receiver front end." I assume the 150 V developed by D11-D14 is with 100 Watts applied. At 40 W, I get 90 V. Seems reasonable. What am I missing here? I must be missing something obvious... can't see the forest for the trees, so to speak. Because someone will ask... the switching between Main and Aux RX antennas works fine. I sure wish TT had included a voltage chart in the Omni VI Plus manual, like they did for the old PTO-era rigs. Any suggestions?