the shutters, loads
computer protection commands:
    shutter
    gr430protect
dual beam enable protection
Normal procedures

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The shutters, loads:

    We have shutter/receiver protection to protect the receivers when we transmit with one of our transmitters (sband,430, hf). They are remotely controlled by the shutter command (issued from vxWorks). The  protection can be grouped into:

• Controlled by shutter command
• gr430 - jennings relay:50 ohm load, or antenna
  
• this is also controlled by the 430 ch load/antenna switch. closed always wins
• the shutter command can be disabled for the gr430 using the dual beam enable  procedure below.
• In this case jennings relay polA is controlled by the ch430 ant/load switch. polB will always be on load.
• 327 rcvr: this is a 50ohm load,ant relay.
  
• This is also controlled by the ch430 ant/load switch. closed always wins
• sbw,sbh,cband,cbh,xband
  
• These all have automatic shutters that cover the horn.
• sbw,xband are pneumatic, sbh,cband,cbh are electric.
  
• alfa:
• manual shutter. automatic shutter is still pending
• lbw:
• no automatic shutter, There is a wire mesh that is placed over the horn
• ch430:
• controlled by ant/load switch for 430 xmiter

Notes:

• When the 430 xmiter high voltage is on, an interlock closes the shutters (electrial shutters only , or both?). The gr430 will not close if dual beam enable has been done.

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Computer protection commands:

shutter command
gr430protect command

The shutter command

    This is a procedure that issues vxWorks commands. You enter this at the vw% prompt
helpdt shutter will give:

shutter - open,close, or query the receiver/radar shutters

SYNTAX:
    shutter               .. query the current state
    shutter {o}pen        .. open  the receiver (sbw,cband) shutter
    shutter {c}lose       .. close the receiver (sbw,cband) shutter
    shutter {rdr}open     .. open  the radar    (sb narrow)  shutter
    shutter {rdrc}lose    .. close the radar    (sb narrow)  shutter

DESCRIPTION
    Open, close, or query the receiver shutters. These shutters are
used to protect the receivers from our transmitters. The sband wide an
d
cband shutters open/close together. The sband narrow receiver shutter
open/closes with the rdropen, rdrclose requests.  You only have to
type in what is in { }  (but don't enter the {}.
shutter with no arguments will list the current state.
This routine calls if1 with the keywords to manipulate the shutter.

Example:
shutter            .. query current state
  current setting: cb,sbw: closed  sbradar:closed
            usage: shutter open close rdropen rdrclose

shutter open        .. open the cband, sband wide shutters.
shutter rdrclose    .. close the sband narrow shutter.

SEE ALSO:if1, sbsh
LASTMOD :shutter        :09mar00

gr430protect:

    This vxWorks command is used to protect the other dome receivers when the 430 xmiter is used. it will:

• close the dome shutters.
• shutter close
• shutter rdrclose
• turn off the alfa amplifiers
• set the upstairs if/lo to look at sband tx. this gives the best switch isolation from the 430 path (only useful if single beam 430).
  
• set the downstairs if/lo to take its input from the gregorian dome, This is to keep the ch 430 path out of the downstairs if/lo (only useful if single beam)
  

If you are using 430 dual beam, then the last 2 steps will be overridden when you setup the gr430 receiver:
Warning:: if you setup the gr430 receiver (ifsetup) and then enter gr430protect, then you will undo the gr430 setup.. and will have to do it overagain.

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Dual beam enable. Shutters closed, 430gr on load/ant switch

    When the 430 dome is being used, we want to close all shutters, but leave the 430 dome receiver under control of the  ch load/antenna switch (above the oscilloscopes in receiver room). The  steps below are part of the standard dual beam setup. It is also done when we test the hf xmiter using the 430 receiver. 
  

Enabling dual beam protection.

• in control room issue close shutter command (in vxWorks:
• vw%  shutter rdrclose
• This is to insure that the sband narrow shutter gets closed
  
• upstairs in dome
• put radar,astronomy switch on radar
• picture before (in astronomy mode)(.gif)
• push black knob into switch to engage mechanism
• twist (with knob still pushed in ) until marker moves to radar
• picture after (in radar mode) (.gif)
• enable dual beam shutter protection box.
• This will disable any shutter commands coming from downstairs. The cmd input is replaced by a 50 ohm load
• picture before (.gif)
• The 50 ohm, thru is a momentary switch the you lift up or down
  
• turn box on. lift switch on left. red led should start blinking
• toggle  50 ohms/thru switch up to move to 50 ohms. This is a momentary toggle. it doesn't stay up.
  
• lower switch on left to turn off system (red led stops flashing)
• picture after (.gif)
• detach waveguide switch from 430 waveguide transition
• these are 3/4 inch bolts
  
• picture before detaching(.gif)
• picture after detaching (.gif)
• Put the screws back in the holes, so they don't role around if the floor moves

Undoing dual beam protection

• put radar,astronomy switch back to astronomy
• dual beam shutter protection
• turn on red led on left
• toggle  thru/50 ohm switch down to return to thru.
  
• move led switch on left down to turn off system
• attach  wave guide switch on 430 waveguide transition.

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