We noticed that the T/R pulses were not in line and shifted on the order of microseconds. These pulses were also shifted/delayed so much that they were cutting into the RF drive pulse. The shift between T/R pulses from each radar was later found to be an issue with going through 13 TXs versus going through 16 TXs. But then this brought up another issue...
We found a problem with the interfacing of the Interface Box with the transmitter on the T/R signal. High impedance logic chips in the I. Box were trying to drive low impedance chips/circuits in the transmitter. This mismatch was causing a 17-18 microsecond delay through the first transmitter that the T/R signal was connected to. Even the transmitter to transmitter connections were slightly a miss, but the 2 second transmitter only has 4 microseconds of delay. There is some need of re-design here as any field modifications helped, but did not completely solve the problem.
Aside from this, we sealed up the lightning protection devices that we installed on the coaxial cables at the base of the antenna pole. We also took out the two bad controller cards to be taken back to the lab for repair. Before much of the T/R pulse madness, Nathaniel and I also tried to diagnose and analyze why the 5 digit noise was occurring on the real time display. We have some leads, but nothing definite until we sort it all out.
The travel day back was fairly uneventful (no almost missed flights). We were a bit delayed by a flight, but made it back to the CRC by 11 pm. Looks like Nathaniel and I already have things to work on for Monday.
End of Day 3 Update:
Spent today doing a simple modification to the interferometer phasing cards fresh in from Alaska (Thanks Todd, Jef, and their grad student?) and then installing them into the receiver rack. We also took a look at a few more things with turning transmitters on and off and disconnecting RF lines in various places. That's why the data from today may look a bit funny and scattered.
The day's other big accomplishment was installing the coaxial lightning protection devices on all of the interferometer lines and a quarter of the main array lines. The installation went fairly smooth with the exception of me breaking a tap in one of the tabs. We also started to investigate the "high" noise levels seen and where they are coming from.
End of Day 2 Update:
Our travel day was a bit adventurous, but we both made it with all of the equipment (including an 88.5 lb Pelican case).
After today we've got most (13 out of 16) transmitters running on Fort Hays East! We also were able to find which line the lightning struck on the east radar. Tomorrow we'll be looking for some phasing matrix cards to again provide interferometer data to Fort Hays East. Also, we'll be installing coaxial lightning protection devices to help protect our ground coaxes and electronics.
Trip Summary:
SuperDARN Engineer Kevin Sterne and Ph.D. student Nathaniel Frissell will be heading to Fort Hays, KS to make repairs on and inspect the Hays SuperDARN radars. The work will include installation of new lighting protection equipment, replacement of transmit-receive switches, as well as work on the interferometer electronics.
