Summary:
Nonsense hardware manufacturing error.
5-coax multi connector on 36/45MHz WFS (originally ASAIR WFS) is mechanically rotated 180 degrees relative to 9/45MHz REFLAIR WFS, and the connection inside WFS head itself is apparently screwed up such that what is supposed to be connected to P1 is actually connected to P5, P2 to P4, and P3 to P3. In other words, the connector looks like the mirror image of what it should be. This is the issue for both of the two 36/45MHz WFS we have (S/N 1300512, which we used yesterday, and S/N 1300511, which was a spare on ISCT6).
This caused the test input on the WFS head to be routed to Q1 LF (i.e. quadrant 1, 36MHz) on the feedthrough. Nothing worked yesterday (alog 26942) because of this.
Instead of fixing WFS, I externally rerouted the cables.
In addition, the multi-coax connector on the WFS side is/was kaput (this was on S/N 1300512) so I had to use S/N 1300511.
Now RF works. Next step would be to connect up the demod.
Cabling/Connector issue details:
Each WFS has one 5-coax RF connector, and one 4-coax RF connector (and one DC interface connector).
4-coax thing is connected to Q3 LF, Q3 HF, Q2 LF and Q2 HF from right to left when you look at the WFS from the front, and both the cable and the cabling were good: All four coax cables were labeled and routed to correct feedthrough.
5-coax connector thing seemed to be a mirror image of what it should be as far as the cable routing was concerned:
| Multi coax on WFS head | feedthgourh |
| Q1 LO | test |
| Q1 HI | HF4 |
| Q4 LO | LF4 |
| Q4 HI | HF1 |
| TEST | LF1 |
Look at the first attachment showing the connectors on 9/45MHz WFS on the left and 36/45MHz WFS on the right, and you'll find that 5-coax multi connector is rotated 180 degrees on the 36/45MHz unit. We have two 36/45MHz units, and both exhibited this error. My guess is that this error was there when these units were shipped to LHO.
You can also see that the 4-coax multi connector on the 36/45MHz S/N 1300512 is broken.
I replaced the WFS with S/N 1300511, and externally rerouted:
| Multi coax on WFS head | feedthgourh |
| Q1 LO | LF1 |
| Q1 HI | HF1 |
| Q4 LO | LF4 |
| Q4 HI | HF4 |
| TEST | test |
RF TF measurements:
After the above mentioned fix, I measured the transfer function from outside of the table via feedthrough, and things made sense.
Second attachment shows the transfer function from test input to LF1, LF2, LF3, LF4, HF1, HF2, HF3, HF4, in this order.
Labeling issue:
BNC end of 5-coax multi connector have labels that don't quite make sense. I didn't quite figure out what kind of error this is, and I didn't fix this as I don't know what's the right thing to do. Anyway, right now they are as follows:
| Multi coax on WFS head | label on BNS |
| Q1 LO | test |
| Q1 HI | H4 |
| Q4 LO | L1 |
| Q4 HI | H1 |
| TEST | L4 |
I will never know how this happened, but obviously it did. 1. Is this the first time the in-air WFS chain has been used? 2. How did the connector get destroyed as seen in the photo? The sidewall of the connector is torn. 3. It is not hard to fix the connector flip, but the damaged connector will need to be replaced at this point. Please send the damaged units back to Caltech for repair (S1300512 and S1300501) and I will fix them myself.