Hi Guys, This one has me scratching my head; maybe you've seen it before. VHF /\/\otorola MSR-2000, configured for repeater (RT) operation by me. It was originally a line controlled station, not a repeater. I followed the jumper setting in the service manual, and some advice from readers of this list.
It transmits and receives on the (still) commercial frequencies. The bug-a-boo seems to be with the station control card. If I power up the station and slide the card in, the transmitter keys immediately, and I note that the Disable LED is dimly lit. Sliding the PL disable switch to the right brings the disable LED to full brightness, transmitter is still keyed. Sliding the line disable switch to the right, the transmitter drops and the disable LED comes to full brightness. If I key the transmitter with the XMIT switch, the transmitter keys, and it will un-key when the XMIT switch is released..as long as the line disable switch is activated (in the disable position). If I key the transmitter via the XMIT switch with the line disable switch the normal (not disabled) position, the transmitter remains keyed after I release the XMIT switch; that's not supposed to happen. The above described behavior takes place with either of two station control modules, so I think the problem is elswhere. While chasing this problem, I noted that pin 19 on the station control module (Line Disable) doesn't go fully to 12V when the transmitter isn't keyed; it hovers around 9 volts. I think this partial path to ground is enough to dimly illuminate the Disable LED. Of course, if I activate the Line Disable switch, it goes to ground as it should & the LED is bright. In reading the control chassis interconnect chart, I see that pin 19 (line disable) of the station control module connects to pin 18 of the DC Transfer card and pin 7 of the Guard Tone card. I removed both of these from the card cage before finding the above described keying problem. Could there be something on the back plane of the control shelf causing this? Thank you, Thanks, Robin Midgett K4IDC VHF+ Glutton EM66se
