Data Room Cabling

SpectroCam usually communicates with the data room through one set of patch panel cables called CASS 8 (in the Cass. cage) and DR 9 (in the Data Room), although any available pair will work. Make sure the two patch panels are connected together, and that all other cabling is removed from both ends before connecting any of the SC-10 equipment. The Cass cage panel should already be connected to the dewar with the special cable as described in Electronics and Cabling.
The lines have the following functions:
```
CASS 8-1    N.C.
       2    N.C.
       3    PC Ethernet card
       4    N.C.
       5    Flip Mirror control (through Utility Box)
       6    10 Hz scope sync. for peaking up on the secondary 
               (through Utility Box)
       7     TTL chopper drive signal from the PClock Box 
               (through Utility Box)
```
In the DATA ROOM the coax lines in DR 9 are hooked up as follows. Use the special SC-10 patch panel cable -- its BNC cables are preset to the correct lengths.
```
 
  DR 9-1    N.C.
       2    N.C.
       3    To Sun Workstation Ethernet transceiver
       4    N.C.
       5    To the  Flip Mirror Output BNC on the back 
               of SC-10 control box.
       6    To the Chopper Drive BNC on the SC-10 control box.
       7    To the TTL Input on the SC-10 control box.
```
Connect a BNC cable from Chopper Drive on the SC-10 box front panel to the f/70 chopper input (cable usually plugged into the function generator), and the upper beam on the rack-mounted oscilloscope.
The Chop Sense BNC from f/70 should go to the lower scope channel. This may be already hooked up.
On the SC-10 box, set the Gain to about 60 (a 30" chop) and the Offset to 490.
Be sure to put a shorting cap on the second input to the input amplifier on the back of the f/70 control panel. Don't forget to take it off when the run is over.
Turn on the f/70 Main and Remote power, wait a few minutes for the Remote to warm up, and set the Remote/Local switch to Local (enabling local switch control of the lid).
Set the SC-10 box Chopper switch to ``1'' and look at the chopper sense signal on the upper trace of the scope. There is usually a 5 mV p-p 60 Hz signal with lots of higher frequency noise. This corresponds to 0.1 arcsec p-p.
Set the Chopper switch to "RUN" and verify that square waves appear on both scope channels.

The Gain and Offset values required for several typical chop amplitudes are given in Table 2.3 .

Table 2.3: Chopper Gain and Offset Settings
Chop p-p (")	Gain	Offset	Volts p-p
20	40	490	1
40	86	490	2
60	132	490	3
120	280	490	6

The transfer coefficient for the chopper is 50 mV / arcsec