Unit causes the transmit radio to "pulse". Will not stay keyed up, receive radio gets a solid green light but transmit radio glows red for maybe 5-7 seconds, then goes quiet, then starts again and repeats this cycle. Have tried several radios on the transmit side, all do the same. HAVE TURNED ON vOX, indications are the same. Box has new batteries, Unbits used are a GT-3 for receive, transmit either a F8HP or a Wouxun uv-8dr. Internet, have not found much as to settings. Unit pretty simple, just plug into each radio, and turn on. Unit allows two ht's to operate as a cross band repeater. I know the Wouxun is a cross band by itself but it was just one I plugged in for testing. Looking for some ideas.