If feedback complains:
CTL Task - Need energy gain above 2145 MeV - Add klystronsthen it is out of energy headroom. That is it would like to get sectors 17 and 18 to give more energy, but it cannot do this while leaving sufficient headroom for fast feedforward and maintaining the proper BNS phase. You can see the previous section on headroom for more details.
If you can, do as the message suggests and add more klystrons. Of course, these must be upstream of LI20. If LI17 or LI18 klystrons are turned on, you should warm start the loop (turn it off and back on). If it is not possible to turn on more klystrons then try the following things.
First look at the SCAVENGER ENERGY LOOP SUMMARY display. Make sure both feedback and fast feedforward are ON. If fast feedforward is OFF and the energy headroom that feedback leaves for it is non-zero (displayed as the distance between the Energy w/ BNS and Max. Fbck E on the second bar graph from the left) then that is probably the source of your problem. Either turn fast feedforward on, or set the headroom to 0. Both of these can be done from the FEED FOWRD EP01 panel which can be reached from the FEEDBACK SYSTEM INDEX.
If that looks OK, then check that the REQUESTs and READBACKs shown on the summary display are roughly equal (say within one symbol height of each other). If they are different, you probably have a feedforward hardware problem. Call an expert.
If the whole summary display looks OK and it indicates that the FEEDFORWARD + FEEDBACK ENERGY request is near the maximum ENERGY W/BNS then you probably have a mis-phased sector or back-phased tube. Use the klystron golding system to check for this.