[evlatests] L301 Settings at L-Band

[Jim Jackson]

Oops, I missed that 13184 MHz cuts off the bottom end of L-band. An L301 
setting of 12928 Mhz should still be reasonably good, though I'm not sure 
it is attenuated quite as well as 13184 MHz. I'll make some more 
measurements in the lab to compare them.  If it's still a problem we may 
need to re-visit the spec of this filter. It is a small connectorized part 
that is fairly painless to replace if needed - it would mainly be a matter 
of cost.

Another possibility would be to see if the L302 design could actually be 
pushed to work a couple hundred MHz higher.  Right now, the MIB software 
stops it at 14.8 Ghz.  I'm not sure if anyone has ever tried to push the 
hardware any higher. Maybe that's an experiment we should try sometime but 
it will need to wait until after we sort out the DDS situation.

Jim

At 11:57 AM 3/17/2006, Ken Sowinski wrote:

> > an L301 setting of 12928 MHz is the lowest we would
> > recommend,  13184 MHz would be better.
>
>If the L301 tuning is raised, the L302 tuning must be raised by the
>same amount to keep the sky frequency fixed.  Assuming the L302 upper
>tuning limit is 14800 MHz, using an L301 setting of 13184 MHz limits
>the lower edge available to L band to 1264 MHz.  If we use an L301
>setting of 12928 MHz we can tune down to 1008 MHz.  The experiment
>we are planing for tonight will use 12928 MHz for the L301.
>
>The same argument means that part of the VHF band, including 75 MHz
>(really 1024 + 75 = 1099 MHz), would be excluded as well if 13184 MHz
>is used.  We will have to use an L301 of 12928 MHz or lower to observe
>in the 75 MHz band.  P band (300 MHz) would work in either case.
>
>Ken