[evlatests] antenna 24 AC - update

[Ken Sowinski]

On Wed, 10 Jan 2007, Jim Jackson wrote:

> Sorry, I lied - we  don't have the spare L302 rev C needed to do this right
> now. We need to get one ready and will make the change when we can.  We
> could break antenna 17 to fix it but since that antenna is ready for first
> fringes as of today and 24 is still useable the way it is, Rob and I both
> decided we would rather not do that.
>
> After checking the L302-1 in 24 and thinking about this a little, I think
> this could be a symptom of the AGC instability we have seen in some L302's
> - this particular module is still operating using the AGC based firmware
> (rev 0.201). The latest firmware (rev 0.21 and up)  eliminates the AGC and
> sets output level using a lookup table. The synthesizers we have done that
> to seem considerably more stable in output level stability  and lock
> reliability.  Unfortunately we can't just upload the MIB new firmware to
> the module - it has to come to the lab and be run through a calibration
> procedure to generate the lookup table.
>
> We will advise when we make the change

Today it looks like 24AC is still doing this so I guess
nothing has been done yet.  If it looks like it will be
a while before the lab calibration can take place I vote
for cannibalizing antenna 17 now that we have seen first
fringes.

The issue we have with antenna 17 is apparant poor sensitivity
and one IF pair is sufficient to chase that.

Ken