Using Synthesizer #2 for the Phase Lock Loop		26 Mar 97

	The FEORGA program can now send a frequency to the second HP 
synthesizer.  This is done via "Frontend #2".  This can be loaded with
the rest frequency, etc via the FESET and LINE commands in OBST if one
specifies /RECEIVER_L 2 instead of the default 1.  Once this is done,
the backend(s) selected with the AOS command will be "connected" to
frontend #2 via the OBSINP command(s) CBEn 2.  (SHOW RECEIVER_L to see
which frontend will be chosen.  The Current value for this adverb, not
the Default is the one used.)  To verify the settings in Frontend #2, one
can go into OBSINP and type SHOW FE2.

	In principle, one can connect more than one frontend at a time.
This would be done by the OBSINP command CBEn 1 for the nth backend and
CBEm 2 for the mth backend.  In that case, FEORGA will send frequencies to
both synthesizers.  But since there is currently only one 100 MHz reference
oscillator, one would have to disable the steering of this frequency by
setting the steering range to zero with OBSINP commands RPL1 0 and RPL2 0.
(Normally, these are set to 10 MHz.)  The OBST macros, however, do not now 
support this using two frontends, so one would have to do the OBSINP commands 
CBE and RPL manually.

	(OBSINP will also allow connecting a backend to both frontends via 
CBEn 12 and this would also cause FEORGA to send both frequencies.  However,
the scan header would then be wrong in CLASS, as the backend's would not have
the correct rest frequencies assigned.)