I bought the TRAK 8900-1 on eBay five years ago. Because the 8901-1 GPS synchronizer module wouldn't lock, the seller sent me a replacement 8901-1, but I was unable to get it to lock either. My system didn't come with an antenna. One issue was that the system supplied 12VDC (instead of the more common 5VDC) to the active antenna. TRAK wanted a "fortune" for their replacement antenna, so that option was out. I finally figured out that, apparently, the 8901-1 had a current sensing circuit in its power supply for external antenna. The circuit was apparently configured to disable lock unless the antenna dc power supply current was within a specified "window". My substitute antenna apparently didn't draw enough DC current to make the circuit happy. So I ended-up soldering a 1k ohm resistor, on the board, in parallel with the antenna connector, in order to "trick" the sensing circuit into its "good" window. That made it work, and it locked just fine. (Note: I no longer have the 8900-1, so I'm going by memory regarding the 1k ohm value.)
I might still have the defective, 2nd 8901-1 GPS synchronizer around here some place. But I just looked, and tentatively don't see it anywhere. I've moved twice since I bought the TRAK, so it might be misplaced or hidden in some box somewhere? Best, Greg ----- Original Message ----- From: "Alex Imas" <[email protected]> To: <[email protected]> Sent: Tuesday, December 14, 2010 3:07 PM Subject: [time-nuts] TRAK Model 8900-1 GPS Disciplined Freq Std Hello I found Greg Burnett page with question about TRAK model and I have a question, too. Maybe you can help, where did you buy this unit cause I'm looking for GPS synchronizer Model 8901-1 , for our Trak Modular Frequency/Time System Model 8900-50 and TRAK stopped produce it Best regards Alex _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
